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VIN_LDO
23
GND
20
VIN_LDO_OUT/VIN_LDO is the output and input pins of the buck circuit inside the module, and pin 20 is
the dedicated GND pin of the buck circuit. Because the buck circuit is prone to high-frequency noise,
special attention should be paid to it. It is recommended to use 2.2 μH inductors such as
TFM201610ALM-2R2MTAA (TDK) and 4.7 μF capacitors to ensure that the traces are as short as
possible and the trace width should not be less than 0.4 mm. At the same time, it is recommended to
route the wires away from sensitive signals.
Table 7: Recommended Inductance Parameters
Parameter
Inductance
Tolerance
DCR
Rated current (based on temperature rise）
3.5. WLAN Application Interface
The following figure shows the WLAN application interface connection between FC905A and the host.
3.5.1. SDIO Interface
FC905A is used for SDIO 3.0 interface, supports 1-bit mode or 4-bit mode (automatic detection when
FC905A_Hardware_Design
Internal buck input for the module
Buck circuit dedicated GND pin
FC905A
SDIO
WLAN_EN
WLAN_WAKE
Figure 3: WLAN Application Interface Connection
Wi-Fi&Bluetooth Module Series
Recommend
2.2
± 20 %
< 0.2
1.15
SDIO
WLAN_EN
WALN_WAKE
-
1.35 V
Unit
μH
Ω
A
HOST
-
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