Quectel SC20 Series Hardware Design page 12

Smart Module Series
Figure Index
Figure 1: Functional Diagram ..................................................................................................................... 21
Figure 2: Pin Assignment (Top View) ......................................................................................................... 23
Figure 3: Voltage Drop Sample .................................................................................................................. 35
Figure 4: Star Structure of the Power Supply ............................................................................................. 35
Figure 5: Reference Circuit of Power Supply ............................................................................................. 36
Figure 6: Turn on the Module Using Driving Circuit ................................................................................... 37
Figure 7: Turn on the Module Using Keystroke ......................................................................................... 37
Figure 8: Timing of Turning on Module ...................................................................................................... 38
Figure 9: Timing of Turning off Module ...................................................................................................... 39
Figure 10: RTC Powered by Coin Cell ....................................................................................................... 39
Figure 11: RTC Powered by Capacitor ...................................................................................................... 39
Figure 12: Reference Design for Battery Charging Circuit ........................................................................ 41
Figure 13: USB Interface Reference Design (OTG is not Supported) ....................................................... 43
Figure 14: USB Interface Reference Design (OTG is Supported) ............................................................. 43
Figure 15: Reference Circuit with Level Translator Chip (for UART1) ....................................................... 45
Figure 16: RS-232 Level Match Circuit (for UART1) ................................................................................. 45
Figure 17: Reference Circuit for (U)SIM Interface with an 8-pin (U)SIM Card Connector ........................ 47
Figure 18: Reference Circuit for (U)SIM Interface with a 6-pin (U)SIM Card Connector .......................... 47
Figure 19: Reference Circuit for SD Card Interface ................................................................................... 49
Figure 20: Reference Circuit for Motor Connection ................................................................................... 55
Figure 21: Reference Circuit Design for LCM Interface ............................................................................. 57
Figure 22: Reference Design for External Backlight Driving Circuit .......................................................... 57
Figure 23: Reference Circuit Design for TP Interface ................................................................................ 58
Figure 24: Reference Circuit Design for Rear Camera Interface .............................................................. 60
Figure 25: Reference Circuit Design for Front Camera Interface .............................................................. 62
Figure 26: Reference Circuit Design for Microphone Interface ................................................................. 65
Figure 27: Reference Circuit Design for Earpiece Interface ...................................................................... 66
Figure 28: Reference Circuit Design for Headphone Interface .................................................................. 66
Figure 29: Reference Circuit Design for Loudspeaker Interface ............................................................... 67
Figure 30: Reference Circuit Design for Emergency Download Interface ................................................. 68
Figure 31: Reference Circuit Design for Main and Rx-diversity Antenna Interfaces ................................. 80
Figure 32: Reference Circuit Design for Wi-Fi/Bluetooth Antenna ............................................................ 81
Figure 33: Reference Circuit Design for GNSS Passive Antenna ............................................................. 82
Figure 34: Reference Circuit Design for GNSS Active Antenna ................................................................ 83
Figure 35: Microstrip Design on a 2-layer PCB ......................................................................................... 83
Figure 36: Coplanar Waveguide Design on a 2-layer PCB ....................................................................... 84
Figure 37: Coplanar Waveguide Design on a 4-layer PCB (Layer 3 as Reference Ground) .................... 84
Figure 38: Coplanar Waveguide Design on a 4-layer PCB (Layer 4 as Reference Ground) .................... 84
Figure 39: Dimensions of the U.FL-R-SMT Connector (Unit: mm) ............................................................ 87
Figure 40: Mechanicals of U.FL-LP Connectors ........................................................................................ 87
Figure 41: Space Factor of Mated Connectors (Unit: mm) ........................................................................ 88
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