PCB Layout Considerations

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					Homework 6: Printed Circuit Board Layout Design
Due: Thursday, October 6


Team Code Name: V.A.V.A. GPS DATA LOGGER                                Group No. 4

Team Member Completing This Homework: Akhil Dharwadkar


  NOTE: This is the third in a series of four “design component” homework assignments, each
  of which is to be completed by one team member. The completed homework will count for
  10% of the team member’s individual grade.


Report Outline:
  Introduction (brief description of design project, with a focus on layout
  considerations)
  PCB layout design considerations (describe the special considerations you took
  into account when designing the PCB layout, including signal routing, trace
  sizing, EMI reduction, etc.)
  Documentation for PCB layout design
    o Updated OrCAD schematic (printed on 11x17 paper)
    o Updated OrCAD design rule check report
    o Updated OrCAD bill of materials report
    o Updated OrCAD routing statistics report
    o Top and bottom copper (printed in color)
  List of References (at minimum, Motorola AN1259)


Evaluation:

Component/Criterion                 Score                          Multiplier    Points
Introduction    &     Layout
                             0 1 2 3 4 5 6 7 8 9 10                X3
Considerations
Documentation for PCB Layout
                             0 1 2 3 4 5 6 7 8 9 10                X5
Design
List of References                  0 1 2 3 4 5 6 7 8 9 10         X1
Technical Writing Style             0 1 2 3 4 5 6 7 8 9 10         X1
                                                                   TOTAL
Introduction


       The       V.A.V.A   GPS   Data   Logger    is   a   data   logging   device   that
logs information like latitudinal and longitudinal (GPS) coordinates, velocity, etc of a
vehicle. The device displays this information to the driver of the vehicle on a LCD which
is mounted on the dashboard. This device also hosts an embedded web server so that the
logged data can be synchronized with a PC using a web interface. An example of this
application would be a car rental company using this device as a fleet management
system for their vehicles. This device consists of two parts – the data logging unit (GPS
Unit) that sits in the trunk of the vehicle and the display unit (LCD Unit) which is
mounted on the dashboard.


       Many PCB layout techniques have been taken into consideration while designing
the PCB layout. Special Emphasis has been laid on reducing EMI; signal routing, trace
width, footprint designs and board-size constraints. Standard PCB layout procedures such
as grounding unused general purpose I/O pins and routing wires at 45 degree turns to
reduce transmission reflection have also been implemented.




PCB Layout Considerations


       Since EMI can be the main cause of problems in a circuit, special focus was given
into EMI reduction. Following techniques have been applied to considerably reduce EMI
in our layout:
       •   Clever component placement techiniques1 have been used to reduce noise
           coupling. The analog components such as the RF transmitter2 and the RF
           receiver3 are placed far apart from all the digital components as well as the
           high current components like the battery chargers4 and DC-DC regulators5.
       •   Effective grounding techniques1 have been used as most EMI problems can be
           resolved using efficient grounding methods. The most effective way of
           reducing total power and ground inductance is to run the signal and the return
           paths very close together. We have exploited the above theory by running the
           power and ground rails with approximately identical geometry on opposite
           sides of the board. Also, star-point grounding was used as a local sub
           grounding point (wherever required) on the layout.
       •   IC decoupling capacitors1 have been used to remove the unwanted glitches
           which occur due to fast switching logic gates. These decoupling capacitors
           have been places very close to all the IC’s so that they can provide
           instantaneous charge. Bulk capacitors1 have also been used so as to recharge
           these decoupling capacitors. We have used a 470uf bulk capacitor which
           should be good enough to recharge all the decoupling capacitors.
       •   CMOS inputs/outputs have very high impedance and consequently can float to
           any voltage if unconnected6, and this voltage could be within a threshold
           switchover region of the gate. To prevent this, all the unused general purpose
           inputs/outputs micro-controller pins have been grounded via a 10 KΩ resistor.
       •   Instead of 90 degree turns, 45 or 135 degree turns have been used at all
           required points to decrease transmission reflections.



       Board-size was one of the major constraints for us while designing the layout.
Since we have two boards, we had to make sure that both occupied a combined area of
less that 60 square inches7. Moreover, since only one board is fabricated for free7, we had
to design both the layouts on a single piece as of now. Once we get the fabricated board,
we will cut it into two parts – the GPS unit and the LCD unit. These two designs are
completely independent of each other and cutting the board into two parts will not affect
the functionality of the either design.


       Regarding trace widths and signal routing, we used an online PCB trace width
calculator8 to find appropriate trace widths for our layout. The calculated trace width for
the power and ground signals was approximately 44 mils, but we ceiled up that value to
50 mils. For all the other signals, we used a width of 12 mils. It was impossible for us to
route all the signals on one layer. Therefore, we used two layers for routing all the
signals. We used 139 Via connectors to switch between the top layer and the bottom
layer.


         Finally, other items that had to be taken into consideration were the footprints and
placement of components like DC power jack9, reset buttons10, GPS receiver11 and the
RCM 330012 micro-controller module. We more or less made the footprints of all our
components just to make sure that we don’t run into problems when it comes to soldering
all components on the PCB. Also, we made sure that DC power jack and the reset buttons
are mounted at one corner of the PCB so that they are easily accessible to the user, the
GPS receiver is mounted in such and a way that the GPS antenna comes out from one
corner of the PCB and finally, the RCM 3300 micro-controller is mounted in such a way
that the RJ-45 Ethernet jack faces outwards.




Documentation for PCB layout design (see attached documents)


    o Updated OrCAD schematic
    o Updated OrCAD design rule check report
    o Updated OrCAD bill of materials report
    o Updated OrCAD routing statistics report
    o Top and bottom copper (printed in color)
References


[1] Motorola AN1259
   http://shay.ecn.purdue.edu/~dsml/ece477/Homework/Fall2005/index.html
[2] RF Transmitter - TXM-315-LC-ND RF
   http://www.linxtechnologies.com/images/products_cat/rf_modules/lc_series/lc-
txm_manual.pdf
[3] RF Transmitter - RXM-315-LC-S-ND RF
   http://www.linxtechnologies.com/images/products_cat/rf_modules/lc_series/lc-s-
rxm_manual.pdf
[4] Battery Charger - MAX713
   http://pdfserv.maxim-ic.com/en/ds/MAX712-MAX713.pdf
[5] DC-DC regulators - MAX738A and MAX1831
   http://pdfserv.maxim-ic.com/en/ds/MAX730A-MAX744A.pdf
   http://pdfserv.maxim-ic.com/en/ds/MAX1830-MAX1831.pdf
[6] The Circuit Designer’s Companion, Author - Tim Williams
    ISBN: 0 7506 6370 7
[7] The ECE department fabricates one PCB having an area less than 60 square inches.
   One board is printed free of cost.
[8] PCB Trace Width Calculator
   http://www.geocities.com/CapeCanaveral/Lab/9643/TraceWidth.htm
[9] DC Power Jack - PJ-102B
   http://www.cui.com/pdffiles/PJ-102B.pdf
[10] Reset Buttons – SW401-ND
    http://rocky.digikey.com/WebLib/Omron%20Web%20Data/B3F.pdf
[11] GPS Receiver - Lassen LP, Trimble
    http://trl.trimble.com/dscgi/ds.py/Get/File-4753
[12] Rabbit Micro-controller – RCM3300
    http://www.rabbitsemiconductor.com/products/rcm3300/rcm3300.pdf
  GND                       RCM Header 1                          GND         GND                         RCM Header 2                       GND                     Debug Header 1                                Debug Header 2

                STATUS 2                    1      GND                       R41     10K                  2             1                                    STATUS 2                  1                           2              1
  R22     10K          4                    3         10K         R21        R43     10K                  4             3           10K     R42                     4                  3                           4              3
  R24     10K          6                    5         10K         R23        R45     10K                  6             5           10K     R44                     6                  5                           6              5
  R26     10K          8                    7         10K         R25        R47     10K                  8             7           10K     R46                     8                  7                           8              7
  R28     10K         10                    9         10K         R27        R49     10K                 10             9           10K     R48                    10                  9                          10              9
                CS    12                    11     WP                        R51     10K                 12             11          10K     R50              CS    12                  11     WP                  12              11
  R29     10K         14                    13     SCLK                      R53     10K                 14             13          10K     R52                    14                  13     SCLK                14              13
                SI    16                    15     SO                        R55     10K                 16             15          10K     R54              SI    16                  15     SO                  16              15
                RXD1 18                     17     TXD1                      R57     10K                 18             17          10K     R56              RXD1 18                   17     TXD1                18              17
                      20                    19                               R59     10K                 20             19          10K     R58                    20                  19                         20              19
                      22                    21                               R61     10K                 22             21          10K     R60                    22                  21                         22              21
  R31     10K         24                    23        10K         R30                                    24             23          10K     R62                    24                  23                         24              23
  R32     10K         26                    25     TX_DATA                                               26             25                                         26                  25     TX_DATA             26              25
  R34     10K         28                    27        10K         R33                      RST           28             27                                         28                  27                RST      28              27
  R36     10K         30                    29        10K         R35                                    30             29                                         30                  29                         30              29
  R38     10K         32                    31        10K         R37                      GND           32             31     VCC_3                               32                  31                         32              31
  R40     10K         34                    33        10K         R39                      GND           34             33                                         34                  33                         34              33


                              RCM3300                                                                         RCM3300                                                   RCM3300                                        RCM3300



                                                                                                          Atmel 8Mb Flash                                                                            VCC_3
                RF Transmitter             VCC_3                                                          AT45D081/SOIC
                                                 R7                                  SI     6                                  7       SO                                  GROUND                    Prime_Power 2            1
  GND                                        GND 10                                                 SI                   SO                                                                                                            TXD1
           1     GND1       GND8       8                                                                                                                                                                         4            3
TX_DATA    2                           7                              C19           SCLK    5                                  23            VCC_3                               GND                             6            5        RXD1
  GND            DATA        VCC             GND                      10uF                          SCLK         RDY/BUSY                                                                                GND
           3     GND3       GND6       6                                                                                                                                                                         8            7
  GND      4                           5     ANT2                                   RST    24                                  28                            GND
                 LADJ        ANT                                  GND               WP              RST                 VCC
                                                                                           25       WP
                                                                                    CS      4                                  1       GND             C35                                                         GPS
                                                                                                    CS                  GND                            10u                                                         GPS Header



(from Car Battery)
  VCC_12                                                                                                                2N6109 Q2

                R16                              R17
                1.4k               C30           150
                                   0.01u
                                                                                                                                          D5                  R20
                                                                  6                             14                                        1N4001              10                                             8
                                                                       TLO            DRV                                                                                                           FB                                   VCC_3
                                                                  5    THI                                                                                                      2           IN      LX       1
                                 C20                                                            2                                                                               4                            3            L3
                                                                                    BATT+                                                 (4.8 V)                                           IN      LX                    2.2u           C31
                                                                11     CC           BATT-       12                                                                             12           VCC     LX       16
                C29                                             16                                               PACK+                                        C34           GND 9                            14                          120u
                10u           0.01u                                    REF                                                                                    470p                          GND     LX
                                                                                FASTCHG         8                                                                               5           nSHDN PGND       13
                                                                 3                                                                                                              6                            15                          GND
                                           R18                         PGM0                                                                                                                 COMP PGND
                                                                 4     PGM1                                                                                                     7           TOFF FBSEL       11
                                           68K                   9                                                                                                                                           10                  GND
                                                                       PGM2                                      PACK-                                        C33                R19               REF
                                                                10     PGM3                                                          C28                      2.2u               39k                                    C32
                                                                  7                                                                  10u                                                                                1u
                                                                       TEMP                                                                        GND                                     MAX738/SO
                                                                  1    VLIMIT
                                                                                                13                                                                                     Step Down Regulator
                                                                                      GND                            Rsense2
                                                                15     V+
                                                                                                                     0.38
                                 R14       C27                          MAX713/S0
                                 22k       1u                         Battery Charger               GND




                           GND



                                                           J5               3.6V DC                       -3.6V DC           VCC_12                1          J10
            SW2                                                             PACK+ 2                  1      PACK-                 C37              2                     Title
VCC_3 1                2    RST            ANT2        1                                                                          470u             3                                   477 Group 4 - VAVA - GPS Schematic

        Reset SPST                                                                                                                                                       Size          Document Number                                                       Rev
                                                           CON1              J11       HEADER 1x2                            GND                       CONN PWR 3-P                                                                                            1

                                                                                                                                                                         Date:              Monday, October 10, 2005             Sheet          1   of   1
                              J12 HEADER 9X2                        GND2                                         RF Reciever
GND2                                                                                                             RXM-315-LC-S                                                                   J8                                           J9
                LCD_DATA1                  18
                SPI_CLK 2                  17        R69                                                ANT 16                     1                                           0.6V DC                       -0.6V DC           3.6V DC                       -3.6V DC
       R63                                       HBQ 10K                              VCC_5             GND2      ANT        NC                                GND2            BAT+ 2                            BAT-           PACK+ 2                         PACK-
                         3                 16                                                               15    GND        NC    2                                                                        1                                           1
       10K      RST2     4                 15        R68                                                    14                     3                R6
                                                                                     C18                          NC         NC
                GND2     5                 14        10K                                                    13                     4     GND2       200          C12
                SPI_BUSY 6                                          R67                     GND2                  NC        GND
                                           13                                                               12    NC        VCC    5                             10u
                nSPI_CS 7                  12            R66        10K                                     11                     6     VCC_5                                                  HEADER 1x2                                   HEADER 1x2
                TOGGLE 8                                 10K        R65                                           NC        PDN                                VCC_5
                                           11                                        10u                    10    NC         NC    7
       R64               9                 10    RS232              10K                                      9                     8     RF_DATA
       10K                                                                                                        NC       DATA

                                                                                                                                                                               GROUND                     RF_DATA        2                        5      RS232
                                                                                                                                                                                                             GND2            T1IN      T1OUT
                                                                                                                                                                                                                         1   T2IN      T2OUT      18
                                                                              GND2                                          VCC_12_2          1           J7                        GND2
                                                                                     C14                                                      2                                                              GND2 4                               3
                                                                                     0.01u                                        C36                                                                        GND2 19         R1IN     R1OUT
                                                                                                                                              3                                                                              R2IN     R2OUT       20
                    GND2                   Fuel Gauge                                                   BAT-              GND2    470u
                                             BQ26231                                    R10                                                                                                                          13                                VCC_5
                            C13                                                   GND2 100k             R13                                   CONN PWR 3-P                                                                    C1+
                                                                                                                                                                                                                     14       C1-       VCC 7
                            0.1u       1                       8                   C15                  0.02                                                                                                         12                                              GND2
                BAT+                       NC       NC                             0.01u                                                                                                                                      C2+
                                       2   VCC     SR1         7                                                                                                                                                     11       C2-
                            GND2       3                       6                                        PACK-                                                                      J6                                15                                       C17
HBQ                                        VSS     SR2                                     R11                                                                                                                                C2+                               1u
                                       4   HBQ     RBI         5                                                                                                                                                     16       C2-
         R9                 R8                                                             100k                         Toggle SPST   SW1                                      1                                      8                                GND2
         100        D3      100                                                                         VCC_5                 VCC_5                 TOGGLE_IN                                                                 V+        GND 6          GND2
                                                                                                                                    1     2                                                                          10       V-        GND 9
                    5.6V                                       C16           D4                   R12                                                                                                                17
                  (500mW)                                      0.1u          1N914                1M                                                                               CON1                                       V-
               GND2                                                       GND2                                          Reset SPST    SW3                               ANT                                                  RS232 Translator
                                                                                                                              VCC_5 1     2           RST2_IN                                                                  MAX233A/DIP




       (from Car Battery)                                                                                                                           GND2
         VCC_12_2                                                                                                   2N6109 Q1
                                                                                                                                                                C6
                    R1                            R2                                                                                                            0.01u                   C10
                    1.4k               C3         150                                                                                                                                   330p         U4                                                  VCC_5
                                       0.01u
                                                                                                                                   D1                                                          8                    12                L2
                                                                                                                                                                                                     CC      LX
                                                                   6     TLO               DRV     14                              1N4001                                                      3     REF     LX     13
                                                                   5                                                                                                                           7                    14                33u
                                     C4                                  THI                                                                              R5                                         SS      LX                                        C11
                                                                                      BATT+        2
                                                                   11                              12                               (7.2 V)               510K          C7                     9                                D2                     100u
                    C1                                                   CC           BATT-                     PACK+                                                   0.1u                         OUT
                                                                   16    REF                                                                                                                   2     SHDN                       1N5817
                    10u            0.01u                                                           8                                                             GND2
                                                                                  FASTCHG                                                                                                                                      GND2               GND2
                                                                    3    PGM0                                                                                                                   1    V+
                                           R3                       4                                                                                                                          15
                                           68K                           PGM1                                                                                                                        V+
                                                                    9    PGM2                                                                                                                  16    V+
                                                                   10                                           PACK-
                                                                         PGM3                                                     C5                              C8           C9                                                           16x2 LCD
                                                                   7                                                              10u                             68u          1u          Step-Down Regulator
                                                                                                                                                                                               MAX738/SO                                    SKD162-632
                                                                         TEMP
                                                                   1     VLIMIT
                                                                                                   13                                                             GND2                                                                             1          GND2
                                                                                           GND                   Rsense1                                                                                                                                      VCC_5
                                                                   15    V+                                                                                                                                                                        2
                                                                                                                 0.52                                                                                                                              3          VCC_5
                                     R4    C2                             MAX713/S0                                                                                                                                                                4          LCD_DATA
                                     22k   1u                           Battery Charger             GND2                                      J13                                                                                                  5          nSPI_CS
                                                                                                                                                          TOGGLE_IN 1                      6         TOGGLE                                        6          SPI_CLK
                                                                                                                                                          GND2      2                      5         VCC_5                                         7          SPI_BUSY
                                                                                                                                                          RST2_IN   3                      4         RST2


                            GND2                                                                                                                                      MAX-6817 Debouncer
                             N:\ee477\combined_project.DRC

 1:
 2:   Checking Pins and Pin Connections
 3:
 4:   --------------------------------------------------
 5:   Checking Schematic: SCHEMATIC1
 6:   --------------------------------------------------
 7:   Checking Electrical Rules
 8:
 9:   Checking for Unconnected Nets
10:
11:   Checking for Invalid References
12:
13:   Checking for Duplicate References
14:
15:   Check Bus width mismatch
16:




                                           1
                               N:\ee477\Combine_Project.BOM

 1:   477 Group 4 - VAVA - GPS Schematic   Revised: Monday, October 10, 2005
 2:             Revision: 1
 3:
 4:
 5:
 6:
 7:
 8:
 9:
10:   Bill Of Materials         October 10,2005        4:48:39   Page1
11:
12:   Item    Quantity    Reference   Part
13:   ______________________________________________
14:
15:   1    3    U2,U11,BQ26231 TXM-LC
16:   2    7    C1,C5,C12,C18,C28,C29, 10u
17:             C35
18:   3    5    C2,C9,C17,C27,C32     1u
19:   4    7    C3,C4,C6,C14,C15,C20,C30   0.01u
20:   5    3    C7,C13,C16 0.1u
21:   6    1    C8 68u
22:   7    1    C10 330p
23:   8    1    C11 100u
24:   9    1    C19 10uF
25:   10   1    C31 120u
26:   11   2    L3,C33 2.2u
27:   12   1    C34 470p
28:   13   2    C36,C37 470u
29:   14   2    D1,D5    1N4001
30:   15   1    D2 1N5817
31:   16   1    D3 5.6V
32:   17   1    D4 1N914
33:   18   2    J5,J6    CON1
34:   19   2    J7,J10 CONN PWR 3-P
35:   20   3    J8,J9,J11     HEADER 1x2
36:   21   1    J12 HEADER 9X2
37:   22   1    J13 MAX-6817 Debouncer
38:   23   1    L2 33u
39:   24   2    Q1,Q2    2N6109
40:   25   1    Rsense1 0.52
41:   26   1    Rsense2 0.38
42:   27   2    R1,R16 1.4k
43:   28   2    R2,R17 150
44:   29   2    R3,R18 68K
45:   30   2    R4,R14 22k
46:   31   1    R5 510K
47:   32   1    R6 200
48:   33   2    R7,R20 10
49:   34   2    R8,R9    100
50:   35   2    R10,R11 100k
51:   36   1    R12 1M
52:   37   1    R13 0.02
53:   38   1    R19 39k
54:   39   49   R21,R22,R23,R24,R25,R26,   10K
55:             R27,R28,R29,R30,R31,R32,
56:             R33,R34,R35,R36,R37,R38,
57:             R39,R40,R41,R42,R43,R44,
58:             R45,R46,R47,R48,R49,R50,
59:             R51,R52,R53,R54,R55,R56,
60:             R57,R58,R59,R60,R61,R62,
61:             R63,R64,R65,R66,R67,R68,
62:             R69
63:   40   1    SKD162-632 LCD
64:   41   3    SW1,SW2,SW3 SW KEY-SPST

                                            1
                               N:\ee477\Combine_Project.BOM

65:   42   1   U3 MAX233A/DIP
66:   43   2   U4,U14 MAX738/SO
67:   44   2   U5,U13 MAX713/S0
68:   45   4   U6,U7,U8,U9 RCM3300
69:   46   1   U10 GPS
70:   47   1   U12 AT45D081/SOIC
71:




                                            2
                                       STATS
*****************************
*                           *
* STATISTICS REPORT         *
*                           *
* N:\PCB\TEMP2.MAX          *
* Mon Oct 10 03:59:24 2005 *
*                           *
*****************************

STATISTIC              ENABLED                TOTAL
---------------------------------------------------------------------
Board Area                59.4                   59.4
Equivalent IC's          37.9                    37.9

Sq. inches per IC        1.57                    1.57

# of pins                 569                     569
Layers                      4                      28
Design Rule Errors          0                       0

Time Used               15:25                   15:25


% Placed              100.00%                  100.00%

Placed                    137                     137

Off board                   0                       0

Unplaced                    0                       0

Clustered                   0                       0


Routed                    350                     350

% Routed               98.87%                  98.87%
Unrouted                    0                       0
% Unrouted              0.00%                   0.00%

Partials                    4                       4

% Partials              1.13%                   1.13%


Vias                      139                     139
Test Points                 0                       0

Vias per Conn            0.39                    0.39
Segments                 1524                    1524



                                      Page 1
                           STATS
Connections         354              354
Nets                114              114
Components          137              137

Footprints          191              191
Padstacks            41               41

Obstacles           684              684


Theoretical Dist   345.7            345.7

Routed Dist        323.5            323.5
Unrouted Dist      29.3             29.3




                           Page 2