Specifications

SIM7912&SIM7906 Hardware Design V1.02
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SD_VDD
46
PO
SD card application: SDIO pull up
power source.
eMMC application: Keep it open when
used for eMMC.
1.8V/3.0V configurable
output.
Cannot be used for SD
card power supply.
SD_DATA0
49
DIO
SDIO data signal (bit 0)
Required 50Ω
impedance
If unused, keep it open.
SD_DATA1
50
DIO
SDIO data signal (bit 1)
SD_DATA2
47
DIO
SDIO data signal (bit 2)
SD_DATA3
48
DIO
SDIO data signal (bit 3)
SD_CMD
51
DIO
SDIO command signal
SD_CLK
53
DO
SDIO clock signal
SD_DET
52
DI
SD card insertion detection
1.8V power domain.
If unused, keep it open.
The following figure shows the SD card reference circuit.
SD_VDD
SD_DATA3
SD_DATA2
SD_DATA1
SD_DATA0
SD_CLK
SD_CMD
SD_DET
VDD
SD_DATA3
SD_DATA2
SD_DATA1
SD_DATA0
SD_CLK
SD_CMD
SD_DET
Module
SD Card
33R
Close to module
100k 100k
100k 100k
100k
470k
VDD_EXT
100nF
100uF
33pF
VDD_2.85V
<5pF
Figure 18: SD card reference circuit
1. The voltage range of SD power supply is 2.7V~3.6V and a sufficient current up to 0.8A should be
provided. As the maximum output current of SD_VDD is 50mA which can only be used for SDIO
pull-up resistors, an external power supply is needed for SD card.
2. The load capacitance of SDIO bus needs to be less than 5pF.
3. If eMMC function is required, SD_DET need to be pull-down to GND.
SDIO interface layout guidelines:
NOTE