Quectel QuecOpen AG521R-NA Hardware Design page 58

SDC1_DATA_0
SDC1_DATA_1
SDC1_DATA_2
SDC1_DATA_3
SDC1_DATA_4
SDC1_DATA_5
SDC1_DATA_6
SDC1_DATA_7
SDC1_CMD
SDC1_CLK
EMMC_RST
EMMC_PWR_EN
SDIO_VDD
Module
Figure 25: Reference Design of SDIO Interface for eMMC Application
Please follow the principles below in eMMC circuit design:
⚫
To avoid jitter of bus, it is recommended to reserve resistors R12–R21 for pulling up SDIOs to
VDD_1.8 V. Resistors R12–R19 are not mounted by default, and the recommended resistor value is
10–100 kΩ.
⚫ In order to improve signal quality, it is recommended to add 0 Ω resistors R1–R9 and R11 in series
between the module and eMMC. Resistor R10 should be 30-35 Ω. The bypass capacitors C1–C11
are reserved and not mounted by default. All resistors and bypass capacitors should be placed close
to the module.
⚫
It is important to route the SDIO signal traces with total grounding. The impedance of SDIO data
trace is 50 Ω (±10%).
⚫
Keep SDIO signals far away from other sensitive circuits/signals such as RF circuits and analog
signals as well as noisy signals such as clock signals and DC-DC signals.
⚫
Spacing DATA to DATA/CLK bus is larger than two times of line width.
⚫
Spacing DATA/CLK/CMD to other signals is larger than two times of line width.
⚫
It is recommended to keep the trace length difference between CLK and DATA/CMD less than 1 mm
and the total routing length less than 50 mm. The total trace length inside the module is 17 mm, so
the exterior total trace length should be less than 33 mm.
⚫
Make sure the adjacent trace spacing is two times of the trace width and the load capacitance of
SDIO bus should be less than 40 pF.
AG521R-NA_QuecOpen_Hardware_Design
R12 R13 R14 R15 R16 R17
NM NM NM NM NM NM
R1 0R
R2 0R
R3 0R
R4 0R
R5 0R
R6 0R
R7 0R
R8 0R
R9 0R
R10 30-35R
R11 0R
EMMC_PWR_EN
C1 C2 C3 C4 C5
VDD_EXT
NM NM NM NM NM
AG521R-NA QuecOpen Hardware Design
VDD_1V8
R18 R19 R20 R21
NM NM 10K 47K
DAT0
DAT1
DAT2
DAT3
DAT4
DAT5
DAT6
DAT7
CMD
CLK
RSTN
C6 C7 C8 C9 C10 C11
NM NM NM NM NM NM
Automotive Module Series
VDD_1.8V
VCCQ
C13
C12
1 µF
100 nF
VDD_3V
VCC
C14 C15
100 nF 2.2 µF
VSS
eMMC
57 / 92