Wlan Application Interface - Quectel EC200U Series Hardware Design

Module
SDIO1_VDD
SDIO1_DATA3
SDIO1_DATA2
SDIO1_DATA1
SDIO1_DATA0
SDIO1_CLK
SDIO1_CMD
SD_DET
In SD card interface design, in order to ensure good communication performance with SD card, the
following design principles should be complied with:
⚫
The voltage range of SD card power supply VDD_3 V is 2.7
should be provided. As the maximum output current of SDIO1_VDD is 150 mA which can only be
used for SDIO pull-up resistors, an externally power supply is needed for SD card.
⚫
To avoid jitter of bus, resistors R7
these resistors is among 10
used as the pull-up power.
⚫ In order to adjust signal quality, it is recommended to add 0 Ω resistors R1
module and the SD card. The bypass capacitors C1
resistors and bypass capacitors should be placed close to the module.
⚫
In order to offer good ESD protection, it is recommended to add a TVS diode on SD card pins near
the SD card connector with junction capacitance less than 15 pF.
⚫
Keep SDIO signals far away from other sensitive circuits/signals such as RF circuits, analog signals,
etc., as well as noisy signals such as clock signals, DC-DC signals, etc.
⚫
It is important to route the SDIO signal surrounded with ground on the layer and ground planes above
and below. The impedance of SDIO data trace is 50 Ω ± 10 %.
⚫
Make sure the adjacent trace spacing is more than two times of the trace width and the load
capacitance of SDIO bus should be less than 15 pF.
⚫
It is recommended to keep the trace length difference between SDIO1_CLK and SDIO1_DATA [0:3]/
SDIO1_CMD less than 1 mm and the total routing length less than 50 mm.
3.18. WLAN Application
The module provides an SDIO 1.1 standard WLAN application interface.
EC200U_Series_Hardware_Design
R7 R8 R9 R10
NM NM NM NM
R1 0R
R2 0R
R3 0R
R4 0R
R5 0R
R6 0R
C1 D1 C2 D2 C3 D3 C4
NM NM NM
Figure 25: Reference Circuit of SD Card Interface
–
R11 are needed to pull up the SDIO to SDIO1_VDD. Value of
100 kΩ and the recommended value is 100 kΩ. SDIO1_VDD should be
–
Interface*
+
C10
R11
100 μF
NM
D4 C5 D5 C6 D6
D7
NM NM NM
–
3.6 V and a sufficient current up to 0.8 A
–
C6 are reserved and not mounted by default. All
LTE Standard Module Series
SD Card Connector
VDD_3V
VDD
C9 C8 C7
100 nF 33 pF 10 pF
CD/DAT3
DAT2
DAT1
DAT0
CLK
CMD
DETECTIVE
VSS
–
R6 in series between the
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