SimCom SIM900B Hardware Design page 6

Smart Machine Smart Decision
Figure Index
FIGURE 1: SIM900B FUNCTIONAL DIAGRAM......................................................................................................... 11
FIGURE 2: REFERENCE CIRCUIT OF THE LDO POWER SUPPLY ......................................................................... 14
FIGURE 3: REFERENCE CIRCUIT OF THE DC-DC POWER SUPPLY..................................................................... 14
FIGURE 4: VBAT VOLTAGE DROP DURING TRANSMIT BURST........................................................................... 15
FIGURE 5: THE MINIMAL VBAT VOLTAGE REQUIREMENT AT VBAT DROP .................................................... 15
FIGURE 6: POWERED ON/DOWN MODULE USING TRANSISTOR....................................................................... 16
FIGURE 7: POWERED ON/DOWN MODULE USING BUTTON ............................................................................... 16
FIGURE 8: TIMING OF POWER ON MODULE........................................................................................................... 16
FIGURE 9: TIMING OF POWER DOWN SIM900B BY PWRKEY ............................................................................. 17
FIGURE 10: TIMING OF RESTART SIM900B.............................................................................................................. 18
FIGURE 11: RTC SUPPLY FROM CAPACITOR........................................................................................................... 20
FIGURE 12: RTC SUPPLY FROM NON-CHARGEABLE BATTERY ......................................................................... 21
FIGURE 13: RTC SUPPLY FROM RECHARGEABLE BATTERY .............................................................................. 21
FIGURE 14: SEIKO XH414H-IV01E CHARGE-DISCHARGE CHARACTERISTIC ................................................. 21
FIGURE 15: CONNECTION OF THE SERIAL INTERFACES..................................................................................... 22
FIGURE 16: CONNECTION OF RXD AND TXD ONLY ............................................................................................. 22
FIGURE 17: CONNECTION FOR SOFTWARE UPGRADING AND DEBUGGING.................................................. 23
FIGURE 18: SPEAKER REFERENCE CIRCUIT .......................................................................................................... 24
FIGURE 19: SPEAKER WITH AMPLIFIER REFERENCE CIRCUIT ......................................................................... 24
FIGURE 20: MICROPHONE REFERENCE CIRCUIT.................................................................................................. 25
FIGURE 21: EARPHONE REFERENCE CIRCUIT ....................................................................................................... 25
FIGURE 22: REFERENCE CIRCUIT OF THE 8-PIN SIM CARD HOLDER............................................................... 27
FIGURE 23: REFERENCE CIRCUIT OF THE 6-PIN SIM CARD HOLDER............................................................... 27
FIGURE 24: AMPHENOL C707 10M006 5122 SIM CARD HOLDER......................................................................... 28
FIGURE 25: MOLEX 91228 SIM CARD HOLDER ...................................................................................................... 29
FIGURE 26: RI BEHAVIOUR OF VOICE CALLING AS A RECEIVER...................................................................... 30
FIGURE 27: RI BEHAVIOUR OF DATA CALLING AS A RECEIVER........................................................................ 31
FIGURE 28: RI BEHAVIOUR OF URC OR RECEIVE SMS ........................................................................................ 31
FIGURE 29: RI BEHAVIOUR AS A CALLER ............................................................................................................... 31
FIGURE 30: REFERENCE CIRCUIT OF NETLIGHT .................................................................................................. 32
FIGURE 31: REFERENCE CIRCUIT OF THE KEYPAD INTERFACE ....................................................................... 33
FIGURE 32: TOP AN SIDE MECHANICAL DIMENSIONS OF MODULE （UNIT: MM） .................................... 40
FIGURE 33: RECOMMENDED PCB FOOTPRINT OUTLINE（UNIT: MM）.......................................................... 41
FIGURE 34: BB530-06001-20R BOARD-TO-BOARD CONNECTOR ........................................................................ 42
FIGURE 35 : BOARD-TO-BOARD CONNECTOR PHYSICAL PHOTO .................................................................... 42
FIGURE 36: U.FL-R-SMT............................................................................................................................................... 43
FIGURE 37: U.FL SERIES RF ADAPTER CABLE ....................................................................................................... 44
FIGURE 38: TOP VIEW OF THE SIM900B................................................................................................................... 44
FIGURE 39: BOTTOM VIEW OF THE SIM900B ......................................................................................................... 44
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SIM900B_Hardware Design_V2.01 2012-05-07