Smart Module Series
SA800U-WF Hardware Design
SA800U-WF_Hardware_Design 38 / 106
3.4. Power Supply
3.4.1. Power Supply Pins
SA800U-WF provides 10 VBAT pins, which are dedicated for connection with external power supply.
3.4.2. Decrease Voltage Drop
The power supply range of the module is from 3.55 V to 4.4 V, and the recommended value is 3.8 V. The
power supply performance, such as load capacity, voltage ripple, etc. directly influences the module’s
performance and stability. Under ultimate conditions, the module may have a transient peak current up to
3 A. If the power supply capability is not sufficient, there will be voltage drops, and if the voltage drops
below 3.1 V, the module will be powered off automatically. Therefore, make sure the input voltage will
never drop below 3.1 V.
3.1 V
Voltage
3.8 V
Input current
3 A
Figure 3: Voltage Drop Sample
To decrease voltage drop, a bypass capacitor of about 100 µF with low ESR (ESR = 0.7
Ω) should be
used for the VBAT inputs, and a multi-layer ceramic chip capacitor (MLCC) array should also be used due
to its ultra-low ESR. It is recommended to use three ceramic capacitors (100 nF, 33 pF, 10 pF) to form the
MLCC array, and place these capacitors close to the VBAT pins. The width of VBAT traces should be no
less than 3 mm. In principle, the longer the VBAT trace is, the wider it should be.
In addition, in order to get a stable power source, it is suggested to use a 2000 W TVS and place it as
close to the VBAT pins as possible to increase voltage surge withstand capability.
