Hardware Design V1.01(091226)

SIM900 Hardware Design
Figure Index
FIGURE 1: SIM900 FUNCTIONAL DIAGRAM ........................................................................................................... 14
FIGURE 2: TOP VIEW OF SIM900 EVB ....................................................................................................................... 15
FIGURE 3: REFERENCE CIRCUIT OF THE VBAT INPUT ........................................................................................ 21
FIGURE 4: REFERENCE CIRCUIT OF THE SOURCE POWER SUPPLY INPUT..................................................... 21
FIGURE 5: VBAT VOLTAGE DROP DURING TRANSMIT BURST........................................................................... 22
FIGURE 6: TURN ON SIM900 USING DRIVING CIRCUIT ....................................................................................... 23
FIGURE 7: TURN ON SIM900 USING BUTTON......................................................................................................... 23
FIGURE 8: TIMING OF TURN ON SYSTEM USING PWRKEY ................................................................................ 24
FIGURE 9: TURN ON SIM900 USING DRIVING CIRCUIT ....................................................................................... 24
FIGURE 10: TURN ON SIM900 USING BUTTON....................................................................................................... 25
FIGURE 11: TIMING OF TURN ON SYSTEM USING PWRKEY AND PWRKEY_OUT ......................................... 25
FIGURE 12: TIMING OF TURN OFF SYSTEM USING PWRKEY............................................................................. 26
FIGURE 13: TIMING OF TURN OFF SYSTEM USING PWRKEY AND PWRKEY_OUT........................................ 27
FIGURE 14: TIMING OF RESTART SYSTEM ............................................................................................................. 28
FIGURE 15: STATE TRANSITION ................................................................................................................................29
FIGURE 16: RTC SUPPLY FROM NON-CHARGEABLE BATTERY ......................................................................... 30
FIGURE 17: RTC SUPPLY FROM RECHARGEABLE BATTERY .............................................................................. 30
FIGURE 18: RTC SUPPLY FROM CAPACITOR .......................................................................................................... 30
FIGURE 19: SEIKO XH414H-IV01E CHARGE CHARACTERISTIC ......................................................................... 31
FIGURE 20: CONNECTION OF THE SERIAL INTERFACES..................................................................................... 32
FIGURE 21: CONNECTION OF SOFTWARE UPGRADE AND SOFTWARE DEBUG ............................................. 34
FIGURE 22: RS232 LEVEL CONVERTER CIRCUIT................................................................................................... 34
FIGURE 23: SPEAKER INTERFACE CONFIGURATION ........................................................................................... 35
FIGURE 24: SPEAKER INTERFACE WITH AMPLIFIER CONFIGURATION .......................................................... 36
FIGURE 25: MICROPHONE INTERFACE CONFIGURATION................................................................................... 36
FIGURE 26: EARPHONE INTERFACE CONFIGURATION........................................................................................ 37
FIGURE 27: REFERENCE CIRCUIT OF THE 8 PINS SIM CARD.............................................................................. 39
FIGURE 28: REFERENCE CIRCUIT OF THE 6 PINS SIM CARD.............................................................................. 39
FIGURE 29: AMPHENOL C707 10M006 512 2 SIM CARD HOLDER........................................................................ 40
FIGURE 30: MOLEX 91228 SIM CARD HOLDER ...................................................................................................... 41
FIGURE 31: REFERENCE CIRCUIT OF THE KEYPAD INTERFACE ....................................................................... 43
FIGURE 32: SIM900 SERVICES AS RECEIVER.......................................................................................................... 44
FIGURE 33: SIM900 SERVICES AS CALLER.............................................................................................................. 44
FIGURE 34: REFERENCE CIRCUIT OF NETLIGHT .................................................................................................. 45
FIGURE 35: RESET TIMING ......................................................................................................................................... 46
FIGURE 36: TOP AN SIDE MECHANICAL DIMENSIONS OF MODULE （UNIT: MM）.................................... 52
FIGURE 37：BOTTOM MECHANICAL DIMENSIONS OF MODULE （UNIT: MM）......................................... 53
FIGURE 38: RECOMMENDED PCB DECAL（UNIT: MM） .................................................................................... 53
FIGURE 39: TOP VIEW OF THE SIM900 ..................................................................................................................... 54
FIGURE 40: SIM900 PIN OUT DIAGRAM (TOP VIEW)............................................................................................. 54
FIGURE 41: THE RAMP-SOAK-SPIKE REFLOW PROFILE OF SIM900.................................................................. 56
SIM900_HD_V1.01 26.12.2009
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