YUGE CLM920 TD3 Usage Manual page 50

CLM920 TD3 LTE Module Hardware Usage Guide
SD card circuit wiring notes:
 The SD card power supply has a 3V voltage range of 2.7~3.6V and needs to be externally
supplied with a minimum current of 800mA.
 The maximum output current of the module output power VDD_SDIO is 50mA, which
can only be used for SDIO bus pull-up.
 The clock frequency of the SD card is as high as 200 MHZ, and the trace is preferably
controlled by 50 ohm impedance.
 The length of the signal line should be less than 25mm. The spacing of the signal lines
should be 2 times the line width and cover the ground and keep away from other possible
interference.
 The spacing between the SDIO signal and other signals needs to be greater than 2 line
widths and ensure that the bus load is less than 40pF.
 The pull-up resistor is added to the SDIO signal, the resistance range is 10~100kΩ, the
recommended value is 100kΩ, and it is pulled up to the VDD_SDIO pin of the module.
 In order to ensure good ESD performance, it is recommended to add TVS tube to the SD
card pin and place it near the pin.
Shanghai Yuge Information Technology co., LTD
Figure 3-23 SD card interface reference circuit diagram
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