User Guide

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51
GM500-U1G_A
Hardware Development Guide
SDC2_CLK 112 DO Secure digital controller 2 clock
SDC2_DET_N 114 DI Secure digital card detection
1.8V power domain
If do not need this, leave this pin not connected.
SDC2_PWR_EN 115 DO Secure digital card power enable
1.8V power domain
If do not need this, leave this pin not connected.
VREF_2P85 116 PO Secure digital card signal pull up
power
1.8V/2.85V
Iomax=50mA
Only used for SD card pull up
If do not need this, leave this pin not connected
Additional LDO is required for SD card power supply
(at least 800mA)
SDC2_DET_N
SD2_PWR_EN
SDC2_DATA0
SDC2_DATA1
SDC2_DATA2
SDC2_DATA3
SDC2_CMD
SDC2_CLK
Module
SD_DETECT
SD_D0
SD_D1
SD_D2
SD_D3
SD_CMD
SD_CLK
R1 0Ω
R2 0Ω
R3 0Ω
R5 0Ω
R4 0 Ω
R6 0Ω
VREF_1V8
D7
EN
VOUT
LDO
R12
470KΩ
C7
D8
1UF
C8
33PF
VDD
VREF_2P85
D6
C6
NA
C5
NA
C4
NA
C3
NA
C2
NA
C1
NA
D1
D2 D3
D4 D5
R11
NA
R10
NA
R9
NA
R8
NA
R7
NA
VIN
VIN
VBAT
VBAT
SD Card Connector
Figure 2–35 SD cardreference design
NOTE:
1) The maximum output current of module output power VREF_2P85 is 50mA, which can only be used for
pull-ups on the SDC2_DATA[0:3] and SDC2_CMD lines. The power supply of SD card needs to be
provided from outside the module. Ensure the external LDO regulator for SD Card supports an output
current of at least 800 mA to be compliant with the SD v3.0 specification;
2) In order to ensure good ESD performance, it is suggested to add TVSnear SD Card pins;
3) In order to adjust the signal quality, it is necessary to reserve the series resistance R1 ~ R6, the
recommended value is 0 Ω, and reserve capacitance C1 ~ C6, which is NA by default;
4) The SD Card signal should be grounded and the impedance should be controlled at 50 Ω± 10%;
5) SDC2_CLK and SDC2_ DATA[0:3]/SDC2_CMD needs equal length (the difference is less than 1 mm), and
the total length is less than 50 mm; because the internal wiring length of the module is about 7 mm, the
external wiring length needs to be less than 43 mm;