SimCom SIM808 Hardware Design page 7

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Figure Index
FIGURE 1: SIM808 FUNCTIONAL DIAGRAM ........................................................................................................... 14
FIGURE 2: SIM808 PIN OUT DIAGRAM (TOP VIEW) ............................................................................................... 15
FIGURE 3: DIMENSIONS OF SIM808（UNIT: MM）................................................................................................ 18
FIGURE 4: RECOMMENDED PCB FOOTPRINT OUTLINE（UNIT: MM）............................................................ 19
FIGURE 5: REFERENCE CIRCUIT OF THE VBAT INPUT......................................................................................... 20
FIGURE 6: REFERENCE CIRCUIT OF THE LDO POWER SUPPLY ......................................................................... 20
FIGURE 7: REFERENCE CIRCUIT OF THE DC-DC POWER SUPPLY..................................................................... 21
FIGURE 8: VBAT VOLTAGE DROP DURING TRANSMIT BURST........................................................................... 21
FIGURE 9: THE MINIMAL VBAT VOLTAGE REQUIREMENT AT VBAT DROP .................................................... 22
FIGURE 10: POWERED ON/DOWN MODULE USING TRANSISTOR..................................................................... 22
FIGURE 11: POWERED ON/DOWN MODULE USING BUTTON ............................................................................. 22
FIGURE 12: TIMING OF POWER ON MODULE......................................................................................................... 23
FIGURE 13: TIMING OF POWER ON MODULE......................................................................................................... 23
FIGURE 14: TIMING OF POWER DOWN SIM808 BY PWRKEY .............................................................................. 24
FIGURE 15: RESET CIRCUIT........................................................................................................................................ 26
FIGURE 16: RESET TIMING SEQUENCE.................................................................................................................... 26
FIGURE 17: SIM808 WITH BATTERY CHARGER AND PACK CONNECTION....................................................... 28
FIGURE 18: RTC SUPPLY FROM CAPACITOR........................................................................................................... 30
FIGURE 19: RTC SUPPLY FROM NON-CHARGEABLE BATTERY ......................................................................... 30
FIGURE 20: RTC SUPPLY FROM RECHARGEABLE BATTERY .............................................................................. 30
FIGURE 21: SEIKO XH414H-IV01E CHARGE-DISCHARGE CHARACTERISTIC ................................................. 31
FIGURE 22: CONNECTION OF THE SERIAL PORT................................................................................................... 32
FIGURE 23: LEVEL CONVERTING BY RESISTOR.................................................................................................... 33
FIGURE 24: ISOLATION CIRCUIT BY DIODES ......................................................................................................... 33
FIGURE 25: TX LEVEL CONVERTING BY TRANSISTOR........................................................................................ 33
FIGURE 26: RX LEVEL CONVERTING BY TRANSISTOR ....................................................................................... 34
FIGURE 27: USB REFERENCE CIRCUIT .................................................................................................................... 34
FIGURE 28: RI BEHAVIOUR OF VOICE CALLING AS A RECEIVER...................................................................... 35
FIGURE 29: RI BEHAVIOUR OF DATA CALLING AS A RECEIVER........................................................................ 36
FIGURE 30: RI BEHAVIOUR OF URC OR RECEIVE SMS ........................................................................................ 36
FIGURE 31: RI BEHAVIOUR AS A CALLER ............................................................................................................... 36
FIGURE 32: SPEAKER REFERENCE CIRCUIT .......................................................................................................... 37
FIGURE 33: SPEAKER WITH AMPLIFIER REFERENCE CIRCUIT ......................................................................... 37
FIGURE 34 : MICROPHONE REFERENCE CIRCUIT................................................................................................. 37
FIGURE 35: BLUETOOTH ANTENNA MATCHING CIRCUIT ................................................................................. 39
FIGURE 36: REFERENCE CIRCUIT OF THE 8-PIN SIM CARD HOLDER............................................................... 40
FIGURE 37: REFERENCE CIRCUIT OF THE 6-PIN SIM CARD HOLDER............................................................... 40
FIGURE 38: MOLEX 91228 SIM CARD HOLDER ...................................................................................................... 41
FIGURE 39: AMPHENOL C707 10M006 5122 SIM CARD HOLDER......................................................................... 42
FIGURE 40: PCM REFERENCE CIRCUIT.................................................................................................................... 44
FIGURE 41: LCD REFERENCE CIRCUIT .................................................................................................................... 44
FIGURE 42: SD REFERENCE CIRCUIT ....................................................................................................................... 45
FIGURE 43: TRADITIONAL KEYPAD REFERENCE CIRCUIT................................................................................. 45
FIGURE 44: EXTENDED KEYPAD REFERENCE CIRCUIT ...................................................................................... 46
FIGURE 45: ENHANCE THE ESD PERFORMANCE OF KEYPAD CIRCUIT........................................................... 46
FIGURE 46: KEYPAD DETECTED ............................................................................................................................... 47
FIGURE 47: REFERENCE CIRCUIT OF PWM DRIVE BUZZER ............................................................................... 49
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SIM808_Hardware Design_V1.00 2014.03.27