Smart Module Series
SC690A_Series_Hardware_Design 39 / 105
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 power off automatically. Therefore, ensure that the input voltage
never drops below 3.1 V.
Voltage
3.8V
Input current
3A
Figure 5: Voltage Drop Sample
To prevent the voltage from dropping below 3.1 V, use a bypass capacitor of about 100 µF with low ESR
(ESR
= 0.7 Ω), and reserve a multi-layer ceramic chip capacitor (MLCC) array due to its ultra-low ESR. It
is recommended to use three ceramic capacitors (100 nF, 33 pF, 10 pF) to compose the MLCC array,
and place these capacitors close to VBAT pins. Additionally, add a 4.7 µF capacitor in parallel. The width
of VBAT trace should be no less than 3 mm. In principle, the longer the VBAT trace is, the wider it should
be.
In addition, 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 enhance surge protection.
The following figure shows the structure of the power supply.
Module
VBAT
VBAT
C1
+
C2
C3
C4
D1
C5
GND
100
μ
F
4.7
μ
F 100 nF 33 pF 10 pF
Figure 6: Structure of Power Supply
