smart-meter by lanyuehua


									                                                                                                                                                         Smart meters

Smart meters

Overview                                                  that	must	be	retained	locally	at	any	                        objectives	are	both	driving	the	
                                                          given	point	in	time.	Because	commu-                          adoption	of	solid-state	metering	and	
Utility	companies	worldwide	have	
                                                          nications	are	not	always	reliable,	some	                     dictating	required	feature	sets	at	the	
begun	deploying	smart	meters	to	
                                                          of	these	regulations	require	utilities	                      chip	level.
service	residential	and	commercial/
                                                          to	store	two	or	more	transmissions	
industrial	markets.	Smart	meters	                                                                                      Finally,	the	promise	of	improving	
                                                          to	meet	billing	requirements.	This	
deliver	a	range	of	benefits	including	                                                                                 service	to	customers	represents	an	
                                                          requirement	increases	the	amount	
lower	operational	and	capital	                                                                                         important	goal	of	smart	metering,	
                                                          of	local	on-chip	memory	needed	for	
expenses,	support	for	new	services,	                                                                                   especially	over	the	long	term.	By	
                                                          smart	meter	ICs.	As	a	result,	the	regula-
and	improved	operational	control.	                                                                                     enabling	customers	to	better	manage	
                                                          tory	pressures	of	specific	jurisdictions	
                                                          have	a	direct	impact	on	the	design	of	                       their	own	energy	usage	through	
Smart meter requirements                                  smart	meters	down	to	the	chip	level.                         incentive-based	programs—such	as	
Deployment	of	smart	meters	is	far	                                                                                     direct	load	control,	interruptible	rate	
from	a	“one-size-fits-all”	undertaking.	                  Another	major	driver	of	smart	meter	                         agreements,	and	demand	bidding/
Manufacturers	must	account	for	the	                       functionality	is	improving	local	                            buyback—smart	metering	can	help	
varying	regulatory	requirements	of	                       antitampering	capabilities.	This	is	                         utilities	manage	overall	energy	
each	region,	as	well	as	the	different	                    especially	important	in	developing	                          consumption	patterns	and	cope	with	
functionalities	and	services	required	                    markets	where	electricity	theft	                             peak-demand	challenges.	With	the	
for	different	markets.                                    accounts	for	a	large	percentage	                             right	capabilities	built	into	chip-level	
                                                          of	overall	power	usage.	The	ability	                         solutions,	smart	meter	deployments	
In	North	America,	for	example,	                           of	solid-state	electricity	meters	to	                        can	effectively	lay	the	groundwork	for	
automated	meter	reading	(AMR)	                            detect	and	prevent	tampering	can	                            expanded	customer-service	functions,	
regulations	dictate	the	frequency	of	                     significantly	improve	control	and	cost	                      such	as	wireless	integration	with	ther-
meter	reading	and	data	transmission.	                     recovery	for	utility	companies.	Here	                        mostats	to	automatically	adjust	usage	
They	also	specify	the	amount	of	data	                     again,	high-level	antitampering	                             during	peak-demand	periods.

                              NONISOLATED POWER                    DC-DC

                                                                                                                                        TRANSFORMER DRIVER
                                                                                                                                         FOR RS-232/RS-485
                                                                                                    METERING SoC
                                       VOLTAGE               ACCURATE                              (ADC/CPU/DSP)
                                      REFERENCE                 RTC
                                             OPTIONAL EXTREME                                                                                 COMMUNICATIONS
                                           ACCURACY COMPONENTS

                             REMOTE-                                                                                             SUPERVISOR


                                                                                           INTERFACE               MEMORY                      MAXIM SOLUTION

     Smart meter block diagram. For a list of Maxim's recommended smart meter solutions, please go to:	                                                                                                                                            3
Smart meters

     For	meter	manufacturers	servicing	             cost,	performance,	and	flexibility.	         approach	provide	gain	uniformity,	
     global	utility	markets,	the	above	             They	also	shorten	time	to	market	            offset	uniformity,	reduced	channel-to-
     combination	of	driving	forces	                 and	reduce	component	count.	                 channel	crosstalk,	and	design	
     presents	significant	opportunities	and	                                                     flexibility.	Altogether,	this	yields	a	
     challenges.	Most	utility	companies	            Multiconverter vs. single-                   lower-cost,	high-accuracy	solution	
     are	at	least	considering	the	implica-                                                       with	wider	bandwidth	(2000:1)	for	
     tions	of	future	smart	metering	
                                                    converter designs                            measurement.	
     applications	when	making	today’s	              Two	shortcomings	of	the	traditional	
     deployment	decisions.	Therefore,	              multiconverter	architecture	are	             An	added	benefit	of	these	SoCs	is	
     meter	manufacturers	need	to	be	                reduced	accuracy	from	channel-               their	field-programmable	firmware.	
     flexible,	offering	both	low-cost	              to-channel	crosstalk	and	high	               Because	the	firmware	for	the	
     metering	solutions	and	high-end	               bill-of-materials	(BOM)	costs.	These	        real-time	CE	is	easily	upgradeable,	
     smart	meter	alternatives.	                     designs	tend	to	carry	crosstalk	             designers	can	configure	the	
                                                    between	channels,	necessitating	             hardware	for	measurements	utilizing	
     One	way	that	meter	designers	are	              additional	hardware	and	firmware	            various	current	sensors	such	as	
     addressing	this	dilemma	is	by	using	           precautions.	Additionally,	they	require	     current	transformers,	Rogowski	coils,	
     integrated	system-on-chip	(SoC)	               a	costlier	differential	mode	to	achieve		    and	current	shunts.	This	also	facilitates	
     solutions	that	can	be	adapted	across	          a	wide	analog	input	range	of	2000:1.         support	for	the	tampering	technologies	
     the	entire	spectrum	of	functionality	                                                       required	by	utilities.			
     requirements.	SoCs	deliver	lower	              A	key	innovation	in	the	development	of	
     costs	by	eliminating	the	need	for	             integrated	metering	SoCs	has	been	           Smart meter requirements
     discrete	components.	They	also	                the	Single	Converter	Technology®	
                                                                                                 Automated meter reading
     provide	rich	feature	sets	for	smart	           approach	from	Teridian.	This	architec-
     metering	and	simpler	upgrade	paths	            ture	streamlines	the	metrology	              AMR	systems	are	typically	imple-
     with	minimum	hardware	and	opera-               functions	by	combining	a	single	sigma-       mented	using	one	of	two	approaches,	
     tional	costs.                                  delta	ADC	with	several	multiplexed	          depending	on	the	regulatory	environ-
                                                    inputs	and	a	programmable	                   ment	for	the	particular	country	and	
     Evolution of solid-state                       real-time	computation	engine	(CE).	          jurisdiction.	One	approach	uses	
                                                    This	technology	provides	flexibility	        relatively	high-functionality	metrology	
     metering architectures
                                                    for	customizing	the	DSP	to	utility	          capabilities	at	the	metering	endpoint,	
     The	earliest	solid-state	meter	archi-                                                       while	the	other	approach	focuses	on	
                                                    requirements	with	minimal	upgrades	
     tectures	combined	multiple	ICs	to	                                                          lower	cost	and	simpler	functionality.	
                                                    to	the	hardware	infrastructure.		
     implement	the	required	function-
     ality.	Typically,	a	microcontroller	           Multiplexed	systems	offer	lower	             As	previously	mentioned,	some	
     performed	the	system	management	               cost	compared	to	architectures	that	         regulatory	jurisdictions	have	strict	
     and	display	tasks,	and	multiple	ADCs	          dedicate	separate	ADCs	to	each	              requirements	to	avoid	the	loss	of	
     combined	with	a	fixed-function	                channel.	Multiplexed	designs	                data	and	ensure	metering	accuracy	
     signal	processor	to	handle	the	                achieve	reduced	channel-to-channel	          for	billing	purposes.	With	reads	taken	
     metrology	functions.	                          crosstalk	by	using	switching	circuitry	      at	relatively	short	intervals	(every	
                                                    to	scan	through	a	number	of	input	           15	minutes),	the	accumulated	data	
     The	next	generation	of	meters	used	                                                         is	then	communicated	at	longer	
     proprietary	metrology	ASICs	from	              channels,	sampling	each	one	in	
                                                    rotation	for	processing	by	the		             intervals	(every	8	hours).	However,	
     large	meter	manufacturers	to	combine	                                                       the	regulations	compensate	for	
     A/D	conversion	and	DSP	functions.	             single	ADC.	
                                                                                                 potential	communications	failures	
     However,	this	architecture	still	fell	short	   The	multiplexed	approach	is	particu-         by	requiring	that	at	least	two	data	
     of	providing	the	level	of	integration	         larly	well	suited	for	applications,	such	    builds	always	be	retained	at	the	
     and	configuration	flexibility	needed	to	       as	power	management,	with	separate	          metering	point.	This	means	that	the	
     support	dynamically	evolving	market	           signals	that	are	similar	in	nature.	A	key	   metrology	chip	must	be	capable	of	
     demands.	The	ASIC	approach	also	               requirement	is	the	preservation	of	          storing	up	to	16	hours	of	data.	
     required	a	high	level	of	in-house	R&D	         phase	information	between	the	
     investment	and	entailed	relatively	long	                                                    In	regulatory	environments	that	
                                                    channels.	This	capability	enables	the	
     cycles	for	the	creation	of	each	new	                                                        place	less	stringent	demands	on	the	
                                                    CE	in	a	multiplexed	system	to	perform	
     revision	of	functionality.                                                                  AMR	process,	utilities	minimize	the	
                                                    “simultaneous”	measurements	across	
                                                                                                 cost	of	metrology	functionality	at	the	
     Integrated	SoC	solutions	address	              different	channels.	SoCs	that	use	a	
                                                                                                 meter	(unless	they	determine	that	a	
     these	limitations	by	optimizing	for	           single-converter	multiplexing	
                                                                                                 positive	payback	can	be	achieved		

4	                                                                                                        Maxim	Smart Grid Solutions
                                                                                                              Smart meters

by	using	higher	end	functionality	for	     hour-by-hour	usage	on	the	Internet	         and	detection	of	ambient	magnetic	
antitampering	purposes).                   and	adjusting	their	usage	to	take	          fields.	Substation	meters	may	also	
                                           advantage	of	incentive	rates.	In	           be	used	to	detect	discrepancies	
There	is	long-term	potential	for	cost	     addition,	there	are	plans	for	enabling	     between	the	total	billed	and	the	
savings	by	combining	the	AMR	              wireless	integration	of	smart	meters	       total	generated	power	and	report	
functions	directly	into	the	               with	customers’	thermostats.	This	          them	via	an	AMR	network.	In	order	
metrology	SoC.	Yet,	this	is	unlikely	to	   will	allow	minor	pre-agreed	adjust-         to	prosecute	and	recover	the	costs	of	
be	practical	in	the	near	term,	due	        ments	to	automatically	be	made	to	          stolen	energy,	detailed	information	
primarily	to	fragmentation	of	AMR	         temperature	settings	during	peak	           such	as	the	exact	times	and	amounts	
communications	methodologies.	             periods	in	exchange	for	an	overall	         of	energy	theft	are	critical	pieces	
Communication	links	may	be	based	          rate	reduction.                             of	evidence	that	can	be	captured	
on	modems	(either	fixed	line	or	                                                       through	smart	metering	technology.
cellular	wireless)	or	powerline	           Smart	metering	also	opens	up	the	
communications	(PLC),	with	the	BOM	        possibilities	for	implementing	sub-
cost	ranging	from	$3	for	PLC	up	to	
                                                                                       Chip-level feature require-
                                           metering	strategies	within	larger	
more	than	$20	for	cellular	modems.	        buildings.	By	using	a	single	smart	         ments for smart meters
                                           meter	with	multidrop	communica-             System on chip
Field programmability                      tion	links	to	individual	customers,		
                                                                                       It	is	clear	from	the	evolving	market	
Deploying	higher	end	metrology	            a	utility	can	eliminate	the	need	for	
                                                                                       requirements,	jurisdictional	regu-
chips	that	allow	for	field	programma-      individual	meters	while	still	providing		
                                                                                       latory	differences,	and	varying	
bility	(via	firmware)	enables	utilities	   a	high	degree	of	visibility	into	each	
                                                                                       implementation	approaches	that	
to	bring	down	both	operational	and	        customer’s	energy	usage.
                                                                                       a	single,	universal	solution	is	not	
capital	investment	costs	over	the	                                                     possible.	However,	by	using	highly	
long	term.	This	extends	the	useful	life	   Security mechanisms                         integrated,	flexibly	configurable	SoC	
of	the	infrastructure	and	helps	to	        Antitampering	is	another	key	driver	        metering	solutions	manufacturers	
justify	smart	metering	investments	        for	smart	metering,	especially	in	          can	bring	down	their	R&D	costs	and	
within	rate-based	calculations.            developing	countries	where	electricity	     improve	their	ability	to	serve	the	
                                           theft	is	a	major	cost	concern	for	          entire	range	of	market	requirements.	
Field	programmability	gives	utilities	
                                           utilities.	For	example,	it	has	been	        This	approach	also	helps	future-
much	greater	flexibility	to	adjust	
                                           estimated	that	as	much	as	40	percent	       proof	meter	architectures	to	meet	
policies	in	response	to	changing	
                                           of	the	power	usage	in	Brazil	is	stolen.	    emerging	requirements.
energy	usage	patterns.	For	example,	
the	specific	times	of	day	set	for	         Typical	tampering	techniques	               Key	ingredients	of	smart	meter	
peak-rate	pricing	policies	may	need	       vary	from	intrusive	means	such	             SoCs	include:
to	be	adjusted	as	significant	numbers	     as	breaking	the	meter	housing	
of	users	shift	their	energy	consump-       and	jamming	the	mechanism	to	               •	 Flexible,	multiple-port	communi-
tion,	or	in	response	to	seasonal	          more	subtle	methods	like	applying	             cations	options	to	support	AMR	
fluctuations.	Remote	upgrades	via	         magnets	to	the	outside	of	the	meter	           links,	integration	with	local	
firmware	allow	utilities	to	quickly	       to	saturate	magnetic	components.	              devices	such	as	thermostats,	
tailor	their	rate	incentives	for	          Some	attempt	to	alter	the	char-                and	multidrop	submetering	
customers	to	help	smooth	out	peak	         acteristics	of	the	load	by	adding	             topologies
demand	while	tracking	dynamic	             capacitance,	half-wave	rectified	           •	 Streamlined	multiread	processing	
changes	in	peak-usage	patterns.            loads,	or	instantaneous	high	                  capabilities	such	as	the	Single	
                                           currents.	Others	may	bypass	the	               Converter	Technology	approach	to	
Energy-management services                 meter,	wholly	or	in	part,	which	can	           reduce	unit	cost	by	multiplexing	
Smart	metering	gives	utilities	real-	      cause	an	increase	in	the	AC	current	           inputs	through	a	delta-sigma	ADC	
time	visibility	into	usage	patterns.	      flowing	through	the	meter’s	neutral	           in	conjunction	with	a	programma-
Moreoever,	it	enables	them	to	             terminals.                                     ble	compute	engine
promote	demand-side	management,	
                                           Deployment	of	more	sophisticated	           •	 Support	for	a	variety	of	sensor	
empowering	customers	to	better	
                                           solid-state	metrology	enables	                 inputs	with	minimum	hardware;	
manage	their	own	usage.	For	
                                           advanced	antitampering	measure-                ability	to	adjust	for	temperature	
instance,	the	Californian	utility	PG&E	
                                           ments	such	as	the	reflected	load	              and	other	environmental	variations	
plans	to	offer	customers	enhanced	
                                           (VAR-hours),	neutral	current,	DC	              for	improved	efficiency	and	accuracy
options	such	as	monitoring	their	
                                           currents	invoked	by	rectified	loads,	                                                                                                      5
Smart meters

     •	 Field-upgradeable	firmware	to	         customers	will	experience	significant	    from	the	DS3231M’s	onboard	
        extend	the	useful	life	of	the	         billing	discrepancies	over	time—          temperature	sensor,	a	temperature-
        metering	solution	and	allow	           unless,	that	is,	a	highly	accurate	RTC	   compensation	algorithm	auto-	
        policies	to	be	dynamically	adjusted	   is	used.	                                 matically	adjusts	the	resonant	
        to	optimize	energy	usage                                                         frequency	to	account	for	tempera-
                                               Maxim	has	long	offered	the	industry’s	    ture	effects.	This	approach	ensures	
     •	 Polyphase	monitoring	and	analysis	     most	accurate	timekeeping	solutions	      extremely	tight	accuracy	over	
        capabilities	to	help	manage	energy	    for	metering	applications.	RTCs	          temperature.	Unlike	crystal-based	
        consumption,	enable	load	analysis,	    such	as	the	DS3231	monitor	an	            products,	the	DS3231M	exhibits	less	
        and	optimize	motor	functions           onboard	temperature	sensor	and	           than	±0.5ppm	of	frequency	shift	
                                               adjust	the	load	capacitance	of	an	        after	high-temperature	reflows,		
     •	 LCD	interface	capable	of	support-
                                               embedded	crystal	in	order	to	             and	it	maintains	flat	frequency-	
        ing	multiple	voltages	and	screen	
                                               compensate	for	the	natural	tempera-       stability	characteristics	(<	±5ppm)	
                                               ture	variation	of	the	tuning	fork	        over	the	entire	-40°C	to	+85°C	
     •	 Various	levels	of	internal	flash	      crystal.	Because	the	crystal	and	die	     temperature	range.
        memory	sizes,	along	with	external	     are	calibrated	across	the	full	
        memory-management	capabilities	        operating	temperature	range	as		
        to	support	a	wide	portfolio	of	data	   a	unit,	the	resulting	frequency	
        storage	options                        accuracy	is	better	than	any	              By	leveraging	the	flexible	SoC	feature	
                                               competing	technology.	These	              set	described	above,	manufacturers	
     •	 Several	tamper-detection	mecha-        products	exceed	the	rigorous	             can	effectively	address	the	range	of	
        nisms	to	prevent	energy	theft;	        standards	for	timekeeping	accuracy		      metering	options—from	low-cost	
        support	for	current	transformers,	     in	metering	applications	and	are	         fixed-function	devices	to	premium	
        Rogowski	coils,	and	current	shunts	    armed	with	a	multitude	of	advanced	       devices	that	offer	ample	memory,	
        along	with	their	combinational	        features.	Most	importantly,	they	         reprogrammability,	and	high	
        current-sensing	mechanisms;	open	      eliminate	the	need	for	user	calibra-      accuracy.	As	the	market	for	smart	
        current-sensor	detection               tion,	providing	a	highly	accurate	        meters	continues	to	evolve,	this		
                                               solution	straight	out	of	the	box.         flexibility	will	enable	meter	manufac-
     •	 Ability	to	work	with	single-wire	
                                                                                         turers	and	utility	companies	to	adapt	
        power	measurement	for	special	
                                               Maxim’s	new	MEMS-based	RTC,	              to	the	needs	of	customers	and	the	
        tamper-detection	conditions	
                                               the	DS3231M,	extends	the	benefits	        dictates	of	regulatory	authorities,	while	
        for	single-	and	polyphase	power	
                                               of	the	DS3231.	The	device’s	all-          simultaneously	optimizing	operational	
                                               silicon	resonator	enables	the	            efficiency	and	profitability.
     •	 Built-in	real-time	clock	(RTC)	        low-frequency	and	low-current	
        functionality                          characteristics	of	the	crystal-
                                               based	DS3231	to	be	migrated	to	a	
     Real-time clock                           smaller	package.	Additionally,	the	
                                               DS3231M	offers	extreme	resilience	
     Many	metering	AFEs	integrate	a	           against	high-temperature	assembly	
     reasonably	accurate	RTC,	which	may	       processes,	can	withstand	shock	and	
     drift	as	much	as	60	minutes/year.	This	   vibration	in	excess	of	20Gs,	and	
     inaccuracy	should	not	be	a	problem	       includes	offsets	for	aging.
     if	the	meter	is	connected	to	a	smart	
     network	that	periodically	resynchro-      At	the	heart	of	the	DS3231M	is	a	
     nizes	the	RTC.	If	the	meter	is	not	       temperature-compensated	silicon	
     connected	to	such	a	network,	end	         oscillator.	Based	on	measurements	

6	                                                                                                Maxim	Smart Grid Solutions
                                                                                                           Smart meters
                                                                                                  Featured products

Energy-meter SoCs reduce cost while improving design flexibility and accuracy

71M6541D*/41F*, 71M6542F* (single phase)
71M6543F*/43H* (polyphase)                                                 Benefits

The	Teridian	71M6541D/41F/42F	(single	phase)	and	71M6543F/43H	             • Measurement accuracy meets even the
(polyphase)	are	highly	integrated,	flexible	metering	SoCs	that	              most aggressive global standards
support	a	wide	range	of	residential,	commercial,	and	industrial	meter	       –	 Exceeds	the	IEC	62053/ANSI	C12.20	
applications	with	up	to	Class	0.2	accuracy.	The	devices	incorporate	a	          standards
5MHz	8051-compatible	MPU	core	and	a	32-bit	computation	engine	               –	 0.1%	accuracy	over	2000:1	current	range
(CE);	a	low-power	RTC	with	digital	temperature	compensation;	up	to	          –	 Meets	Class	0.2	accuracy	(71M6543H)
64KB	flash	memory	and	5KB	RAM;	and	an	LCD	driver.	The	proprietary	
Single	Converter	Technology	architecture	includes	a	22-bit	delta-          • High integration and programmability
sigma	ADC,	which	provides	unmatched	linearity	performance	over	              meet changing customer requirements
a	wide	dynamic	range	and	consumes	less	power	than	a	multi-ADC	               –	 8-bit	MPU	(80515);	up	to	5	MIPS
implementation.	Automatic	switching	between	main	power	and	                  –	 Dedicated	32-bit	CE
three	battery-backup	modes	ensures	operational	reliability.	These	           –	 64KB	flash	and	5KB	RAM	
SoCs	operate	over	the	-40°C	to	+85°C	industrial	temperature	range.	             (71M6541F/42F/43F/43H))
The	71M6541D/41F	are	packaged	in	a	64-pin	lead-free	LQFP,	and	the	           –	 32KB	flash	and	5KB	RAM	(71M6541D)
71M6542F/43F/43H	are	packaged	in	a	100-pin	lead-free	LQFP.                   –	 Support	up	to	51	digital	I/O	pins	
The	71M6541D/41F/42F	and	71M6543F/43H	metering	SoCs	also	
feature	a	proprietary	isolation	technology.	By	using	low-cost	resistive	     –	 LCD	driver	supports	up	to	336	pixels	
shunts	and	optional	interfaces	to	one	of	the	Teridian	isolated	sensors	         (71M6542F/43F/43H)
(71M6601*,	71M6103*),	these	metering	solutions	eliminate	the	                –	 Two	UARTs	for	IR	and	AMR
need	for	expensive,	bulky	current	transformers.	This,	in	turn,	reduces	      –	 IR	LED	driver	with	modulation
BOM	costs	and	casing	size	requirements.		The	metering	design	will	         • Accelerate meter development
also	benefit	from	immunity	to	magnetic	tampering	and	enhanced	               –	 Complete	array	of	in-circuit-emulation	
reliability.	                                                                   (ICE)	and	development	tools	
A	complete	array	of	software	development	tools,	demonstration	               –	 Flash	programming	and	firmware	
code,	and	reference	designs	is	available.	These	tools	enable	rapid	             development	tools
development	and	certification	of	meters	that	meet	all	ANSI	and	IEC	          –	 Programming	libraries	and	reference	
electricity	metering	standards	worldwide.                                       designs
                                                                             –	 Third-party	programming	tools	and	
                                                                                support	services
                                                                           • Improved reliability and cost savings
                          (Block diagrams on following pages)
                                                                             –	 Using	shunts	instead	of	current		
                                                                                transformers	(CT)	lowers	BOM	costs
                                                                             –	 Eliminate	the	cost	of	copper	wire	needed	
                                                                                for	CTs
                                                                             –	 Using	shunts	allows	smaller	meter	
                                                                             –	 Using	shunts	enables	gain	magnetic	field	

*Future product—contact the factory for availability.	                                                                                                 7
Smart meters
Featured products

     Energy-meter SoCs reduce cost while improving design flexibility and accuracy
                                                                   SHUNT CURRENT SENSORS

                                                             NEUTRAL                                                                      LOAD


                                                                                                                                           POWER SUPPLY

                                                                                                           THIS SYSTEM IS REFERENCED
                                                                                                           TO NEUTRAL



                                                                                                                                  V3P3A V3P3SYS    GNDA GNDD

                                                                                                               MUX AND ADC                         PWR MODE
                                                                            PULSE                                                 TEMPERATURE

                                                                        TRANSFORMERS                           IN**                 SENSOR
                                                                                                              VC                                      WAKE-UP
                                                                                                                                        RAM       REGULATOR             BATTERY
                                                                                                               IB                                      VBAT_RTC
                                                                                                              VA                  COMPUTATION
                                                                                                                                    ENGINE                          RTC
                                                                                                              IADC0                                BATTERY        BATTERY
                                                                                                              IADC0                                MONITOR
                                                                                                                      VREF                             COM0...5
                                                                                                                                                                             LCD DISPLAY
                                                                                                                                     FLASH                SEG
                                                                                                              SERIAL PORTS          MEMORY
                                                                                   AMR                                                            LCD DRIVER
                                                                                                              RX                                  DIO, PULSES
                                                                                                                                                           DIO                 PULSES,
                                                                                                                             RX                                                  DIO
                                                                                          IR                  MODULATOR                  MPU
                                                                                                                             TX          RTC                            I2C OR MICROWIRE®
                                                                                                                                       TIMERS             V3P3D               EEPROM
                                                                                                                    SPI™                                                    32kHz
                                                                                   HOST                          INTERFACE              ICE               XOUT
                                                                                                             **IN = NEUTRAL CURRENT

                                      The 71M6543F/71M6543H polyphase metering SoCs are ideal for commercial and industrial applications.

                                                                                                          (Block diagram on next page)

     *Future product—contact the factory for availability.

8	                                                                                                                                                                                  Maxim	Smart Grid Solutions
                                                                                                                                                                        Smart meters
                                                                                                                                                                    Featured products

Energy-meter SoCs reduce cost while improving design flexibility and accuracy

                                             NEUTRAL              SHUNT

                                                                                                  LOAD            NOTE:
                                                         LINE                                                     THIS SYSTEM IS REFERENCED TO LINE

                                                                                    NEUTRAL                   POWER SUPPLY


                                                                                                       V3P3A V3P3SYS    GNDA GNDD



                                                            PULSE                   MUX AND ADC
                                                         TRANSFORMER                                   TEMPERATURE      PWR MODE
                                                                                                         SENSOR          CONTROL
                                                                                    IAP                                    WAKE-UP
                                                                                    IBP                    RAM         REGULATOR             BATTERY
                                                                                    IBN                                       VBAT
                                                                                    VA                 COMPUTATION
                                                                                    IADC0                ENGINE                          RTC
                                                                                    IADC0                               BATTERY        BATTERY

                                                                                                                            COM0...5               LCD DISPLAY
                                                                                    SERIAL PORTS         MEMORY                SEG
                                                                                    TX                                      SEG/DIO
                                                                                    RX                                 LCD DRIVER
                                                                                                                       DIO, PULSES
                                                                                                                                DIO                  PULSES,
                                                                                                  RX                                                   DIO
                                                                       IR           MODULATOR              MPU
                                                                                                  TX       RTC
                                                                                                         TIMERS                                  I2C OR MICROWIRE
                                                                                    POWER-FAULT                               V3P3D
                                                                                    COMPARATOR                                                        EEPROM
                                                                                         SPI                                                     32kHz
                                                                   HOST               INTERFACE            ICE                 XOUT

                                   The 71M6541D/71M6541F single-phase metering SoCs are ideal for residential and POL applications.

*Future product—contact the factory for availability.	                                                                                                                                                         9
Smart meters
Featured products

      Highly accurate MEMS RTC is less sensitive to shock and vibration than
      traditional clocks
      DS3231M                                                                                               Benefits

      The	DS3231M	is	a	highly	precise	real-time	clock	(RTC)	based	on	MEMS	                                  • Meets the four core timing require-
      resonator	technology.	It	meets	the	core	requirements	for	accuracy,	                                     ments for smart metering
      stability,	power,	and	compliance	testing	for	smart	meters.	                                             –	 Accuracy	(<	±5.0ppm)
      This	innovative	RTC	provides	temperature-compensated	timing	                                            –	 Stability	(<	±5.0ppm)
      accuracy	of	±0.5s/day	(<	±5.0ppm)	from	-40°C	to	+85°C.	The	MEMS	                                        –	 Power	(<	3.0μA)
      technology	makes	the	DS3231M	less	sensitive	to	shock	and	vibration	                                     –	 Compliance	testing	(1Hz	output)
      than	traditional	crystal-based	clocks.	It	is	also	less	sensitive	to	                                  • Highly rugged, dependable solution
      accuracy	drift,	which	is	quite	common	with	aging	quartz	crystals.
                                                                                                              –	 ±5ppm	lifetime	accuracy
      The	DS3231M	is	a	low-power	device	(<	3.0µA)	that	prolongs	battery	                                      –	 Optimized	for	high	shock	and	vibration:	
      life.	Switching	automatically	between	the	main	and	battery	power,	                                         >	20,000g
      it	meets	the	industry	requirement	for	dual-supply	operation	as	a	                                       –	 Requires	no	special	handling	during	
      safeguard	in	the	absence	of	main	power.	                                                                   ultrasonic	cleaning	vs.	quartz	crystals
      The	DS3231M’s	accuracy	and	stability	make	it	particularly	suitable	                                   • Safeguards against power loss
      for	multitariff	metering.	With	no	crystal	to	consume	space	and	add	                                     –	 <	3.0μA	power	consumption	extends	
      cost,	it	is	a	low-cost	solution	for	time-based	billing	and	rate	charges	                                   battery	life	
      directly	at	the	meter.	It	is	a	viable	option	for	metering	networks	that	                                –	 Dual	supply	operation
      do	not	distribute	time-of-day	information	between	meters,	but	must	
                                                                                                              –	 Automatic	switching	between	main	
      maintain	an	accurate	time	base	at	the	meter.	
                                                                                                                 power	and	battery	power
                                                                                                            • Reduces cost and saves space
                                                                                                              –	 Miniature	MEMS	resonator	eliminates	
                                                                                                                 the	cost	of	a	quartz	crystal
                                                                                                              –	 No	user	calibration	required,	thus	
                                                                                                                 reducing	cost		
                                                                                                              –	 16-	and	8-pin	(150	mil)	SO	packages
                                                                                                              –	 Pin	compatible	with	crystal-based	
                                                                                                                 DS3231S	RTCs


                                                                          DIVIDER                                          N
                        VBAT                                  TIME-BASE                               1Hz      INTERRUPT
                         VCC                                  RESONATOR                                          OR 1Hz    N
                                                    POWER                                 DIGITAL
                                                   CONTROL                              ADJUSTMENT
                                     N                          SENSOR
                                                                                    FACTORY TRIM

                         SDA                          I2C          CONTROL AND STATUS            CLOCK/CALENDAR
                         SCL                      INTERFACE            REGISTERS                   WITH ALARM

                        Block diagram of the DS3231M RTC.

10	                                                                                                                         Maxim	Smart Grid Solutions
                                                                                                                                                        Smart meters
                                                                                                                            Recommended solutions

Recommended solutions

         Part                               Description                                     Features                                            Benefits

Metering SoCs
71M6531/71M6532           Residential metering SoCs with an MPU        Multiple UARTs, I2C/MICROWIRE interface, and up      High integration and field programmability
                          core, RTC, in-system programmable flash,     to 30 DIO pins; support 2-, 3-, and 4-wire single-   enable designers to adapt to changing
                          and LCD driver                               phase and dual-phase residential metering; tamper-   customer requirements, speed time to market,
                                                                       detection mechanisms                                 and lower BOM cost
71M6533/71M6534           Polyphase metering SoCs with 10MHz,          Advanced power management with less than              Higher sampling rate and larger code space
                          8051-compatible MPU core; low-power          1µA sleep current; selectable single-ended or         offer customers ability to extend metrology
                          RTC; 128KB flash; and LCD driver             differential current sensing; large-format LCD driver functionality and implement advanced
                                                                                                                             functions such as simultaneous broadband/
71M6541D*/                Highly integrated single-phase metering      Exceed IEC 62053 and ANSI C12.20 standards;          Measurement accuracy meets even the most
41F*/42F*                 SoCs                                         embedded isolated-sensing technology                 aggressive global standards; offer flexibility in
                                                                                                                            selecting interface
71M6543F*/43H*            Highly integrated polyphase metering SoCs    Exceed IEC 62053 and ANSI C12.20 standards;          Significantly reduce BOM and enclosure
                                                                       embedded isolated-sensing technology                 size by eliminating the need for current
                                                                                                                            transformers in polyphase designs

Real-time clocks (RTCs)
DS3231M                   Extremely accurate, MEMS-based, I²C RTC      All-silicon MEMS resonator; requires no user         Reduces design time; minimizes piece-part
                                                                       calibration; ±5ppm (±0.432s/day) timekeeping         count in manufacturing lines; provides
                                                                       accuracy over -40°C to +85°C                         enhanced aging characteristics and lower
                                                                                                                            sensitivity to shock and vibration; improves
                                                                                                                            long-term accuracy
DS3231                    Extremely accurate, I2C RTC with TCXO and Better than ±2min/yr accuracy (< ±4ppm) over            Single-chip timing solution improves accuracy
                          crystal                                   -40°C to +85°C; requires no user calibration            and lowers design complexity over discrete
                                                                                                                            solutions, which typically require a crystal,
                                                                                                                            RTC, temperature sensor, and microprocessor,
                                                                                                                            as well as user calibration
DS3232                    Extremely accurate, I2C RTC with integrated ±3.5ppm accuracy over -40°C to +85°C; 236 bytes Integrated memory allows storage of battery-
                          crystal and SRAM                            of battery-backed SRAM                          backed data, including billing information or
                                                                                                                      configuration data
DS3234                    Extremely accurate, SPI RTC with integrated ±3.5ppm accuracy over -40°C to +85°C; 236 bytes Integrated memory allows storage of battery-
                          crystal and SRAM                            of battery-backed SRAM                          backed data, including billing information or
                                                                                                                      configuration data

Isolated power
MAX5021/22                High-performance current-mode PWM             Universal power supply (85V to 265V); small         Save board area; ideal for noise-sensitive
                          controllers for forward/flyback configuration SOT23 package; integrated startup circuit           applications

MAX17499/500              Current-mode PWM controllers with            Integrated error amplifier regulates the tertiary    Eliminate the need for an optocoupler and
                          programmable switching frequency             winding output voltage; input undervoltage lockout   ensure proper operation during brownout

MAX5974/75                Active-clamped, spread-spectrum, current-    Active-clamp topology; regulation without           Achieve > 90% efficiency, thus reducing
                          mode PWM controllers                         optocoupler; switching frequency is adjustable from power consumption in synchronous forward/
                                                                       100kHz to 600kHz                                    flyback power supplies; save space and cost
                                                                                                                           by eliminating the need for an optocoupler;
                                                                                                                           optimize circuit magnetics and filter elements
                                                                                                                           to meet EMI requirements

                                                                                                                                            (Continued on next page)

*Future product—contact the factory for availability.	                                                                                                                                                     11
Smart meters
Recommended solutions

      Recommended solutions (continued)

                Part                              Description                                       Features                                           Benefits

       DC-DC converters
       MAX1725/26               12V, ultra-low-IQ, low-dropout linear         20mA output; 2µA quiescent current across             Low-power operation conserves battery life
                                regulators                                    operating range and in dropout; reverse-battery
       MAX15062*                36V, 300mA DC-DC regulator with               Low quiescent current; internal compensation;         High integration with small footprint saves
                                integrated FETs in 2mm x 2mm TDFN             synchronous operation; pulse-skip mode for light      up to 50% total board area compared to
                                                                              loads                                                 competing solutions

       Transformer drivers
       MAX256                   3W, primary-side transformer H-bridge         Provides up to 3W to the transformer in isolated      Saves board area; reduces design complexity;
                                driver for isolated supplies                  power supplies                                        makes it easy to implement isolated power
       MAX253                   1W, primary-side transformer H-bridge         Specifically designed to provide isolated power for   Saves board area; reduces design complexity;
                                driver for isolated supplies                  an isolated RS-485 or RS-232 data interface           makes it easy to implement isolated power

       Hall-effect sensors
       MAX9639*/40*             Low-power, single Hall-effect sensors         Adjustable magnetic thresholds (MAX9639)              Provide simple open/close detection while
                                                                              simplify system design; ultra-low 2.6µA supply        saving power

       MAX6854–69               Supervisory circuits with manual reset and    Ultra-low 170nA (typ) supply current                  Low-power operation decreases drain on
                                watchdog timer                                                                                      battery
       MAX16056–59              Supervisory circuits with capacitor-          Ultra-low 125nA (typ) supply current                  Low-power operation decreases drain on
                                adjustable reset and watchdog timeouts                                                              battery

       Voltage references
       MAX6161–68               Precision, micropower, low-dropout, high-     ±2mV (max) initial accuracy; 5ppm/°C (max)            Improve system precision; reduce component
                                output-current voltage references in an       temperature coefficient                               count and board space
                                8-pin SO package

      For a list of Maxim's recommended smart meter solutions, please go to:

      *Future product—contact the factory for availability.

12	                                                                                                                                      Maxim	Smart Grid Solutions

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