SIM900 Hardware Design
Figure Index
FIGURE 1: SIM900A FUNCTIONAL DIAGRAM......................................................................................................... 15
FIGURE 2: TOP VIEW OF SIM900A EVB .................................................................................................................... 16
FIGURE 3: REFERENCE CIRCUIT OF THE VBAT INPUT ........................................................................................ 21
FIGURE 4: REFERENCE CIRCUIT OF THE SOURCE POWER SUPPLY INPUT..................................................... 22
FIGURE 5: VBAT VOLTAGE DROP DURING TRANSMIT BURST........................................................................... 22
FIGURE 6: TURN ON SIM900A USING DRIVING CIRCUIT..................................................................................... 24
FIGURE 7: TURN ON SIM900A USING BUTTON ...................................................................................................... 24
FIGURE 8: TIMING OF TURN ON SYSTEM USING PWRKEY ................................................................................ 24
FIGURE 9: TURN ON SIM900A USING DRIVING CIRCUIT..................................................................................... 25
FIGURE 10: TURN ON SIM900A USING BUTTON .................................................................................................... 25
FIGURE 11: TIMING OF TURN ON SYSTEM USING PWRKEY AND PWRKEY_OUT ......................................... 26
FIGURE 12: TIMING OF TURN OFF SYSTEM USING PWRKEY............................................................................. 27
FIGURE 13: TIMING OF TURN OFF SYSTEM USING PWRKEY AND PWRKEY_OUT........................................ 27
FIGURE 14: TIMING OF RESTART SYSTEM ............................................................................................................. 29
FIGURE 15: STATE TRANSITION ................................................................................................................................ 30
FIGURE 16: RTC SUPPLY FROM NON-CHARGEABLE BATTERY ......................................................................... 30
FIGURE 17: RTC SUPPLY FROM RECHARGEABLE BATTERY .............................................................................. 31
FIGURE 18: RTC SUPPLY FROM CAPACITOR .......................................................................................................... 31
FIGURE 19: SEIKO XH414H-IV01E CHARGE CHARACTERISTIC ......................................................................... 31
FIGURE 20: CONNECTION OF THE SERIAL INTERFACES..................................................................................... 33
FIGURE 21: CONNECTION OF SOFTWARE UPGRADE AND SOFTWARE DEBUG ............................................. 34
FIGURE 22: RS232 LEVEL CONVERTER CIRCUIT................................................................................................... 35
FIGURE 23: SPEAKER INTERFACE CONFIGURATION ........................................................................................... 36
FIGURE 24: SPEAKER INTERFACE WITH AMPLIFIER CONFIGURATION .......................................................... 36
FIGURE 25: MICROPHONE INTERFACE CONFIGURATION................................................................................... 37
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: ARCHITECTURE OF ADC ....................................................................................................................... 43
FIGURE 33: SIM900A SERVICES AS RECEIVER ....................................................................................................... 44
FIGURE 34: SIM900A SERVICES AS CALLER ........................................................................................................... 45
FIGURE 35: REFERENCE CIRCUIT OF NETLIGHT .................................................................................................. 46
FIGURE 36: RESET TIMING ......................................................................................................................................... 47
FIGURE 37: TOP AN SIDE MECHANICAL DIMENSIONS OF MODULE (UNIT: MM).................................... 52
FIGURE 38:BOTTOM MECHANICAL DIMENSIONS OF MODULE (UNIT: MM)......................................... 53
FIGURE 39: RECOMMENDED PCB DECAL(UNIT: MM) .................................................................................... 53
FIGURE 40: TOP VIEW OF THE SIM900A .................................................................................................................. 54
FIGURE 41: SIM900A PIN OUT DIAGRAM (TOP VIEW) .......................................................................................... 55
FIGURE 42: THE RAMP-SOAK-SPIKE REFLOW PROFILE OF SIM900A............................................................... 57
SIM900_HD_V1.01
6
26.12.2009