Smart Module Series
SC206E_Series_Hardware_Design 36 / 115
3.4. Power Supply
3.4.1. Power Supply Pins
The module provides four VBAT pins for connection with external power supply.
3.4.2. Voltage Stability Requirements
The power supply range of the module is 3.5
–4.4 V, and the recommended value is 3.8 V. The power
supply performance, such as load capacity, voltage ripple, etc. will dire
ctly influences the module’s
performance and stability. Under ultimate conditions, the transient peak current of the module may surge
up to 3 A. If the power supply capacity is not sufficient, there will be the risk that the voltage drops below
3.4 V and as a result the module powers off automatically. Therefore, make sure the input voltage never
drops below 3.4 V.
Voltage
3.8 V
3 A
Input current
Figure 3: Voltage Drop Sample
To decrease voltage drop, 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 main power supply
from an external application has to be a single voltage source and can be expanded to two sub paths
with star structure. 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 guarantee the stability of the power source, please use a TVS and place it as close to the
VBAT pins as possible to enhance surge protection. The following figure shows the star configuration of
the power supply.
