Wi-Fi&Bluetooth Module Series
FC909A_Hardware_Design 20 / 49
The module supports external crystal or built-in crystal, so XTAL_IN and XTAL_OUT are optional pins.
3.3. Power Supply
3.3.1. Power Supply Pins
Table 5: Pin Definition of Power Supply and GND Pins
FC909A is powered by VBAT. It is recommended to use a power chip with a maximum output current of
more than 0.5 A. To ensure better power supply performance, it is recommen
ded to parallel 100 μF
decoupling capacitors and 1 μF and 100 nF filter capacitors near the input of the module’s VBAT.
Meanwhile, it is recommended to add a TVS near the VBAT input terminal to prevent surge voltage. In
principle, the longer the VBAT traces, the wider the traces.
When paired with LTE modules, it is recommended to use 10 pF and 33 pF for C2/C4.
FC909A
VBAT
VBAT
D1
C2
C3
C4
NM
C1
100
μF
1
μF 100 nF
R1
0R
+
Figure 1: VBAT Circuit Reference Design
Pin Name
Pin No.
Description
Min.
Typ.
Max.
Unit
VBAT
9
Power supply for the module
3.0
3.6
4.8
V
VDDIO
22
Power supply for module
’s
I/O pins
1.71
1.8/3.3
3.63
V
GND
1, 3, 20, 31, 33, 36 Ground
NOTE
