Decrease Voltage Drop - Quectel LPWA Series Manual

LPWA Module Series
BG770A-GL Hardware Design
NOTE
1)
When the module starts up normally, to ensure full-function mode, the minimum power supply voltage
should be higher than 3.1 V.

3.5.2. Decrease Voltage Drop

The power supply VBAT_BB range of BG770A-GL is from 2.2 V to 4.35 V, the power supply VBAT_RF
range of BG770A-GL is from 3.1 V to 4.2 V. When the module starts up normally, to ensure full-function
mode, the minimum power supply voltage should be higher than 3.1 V.
To decrease voltage drop, a bypass capacitor of about 100 µF with low ESR should be used, and a
multi-layer ceramic chip capacitor (MLCC) array should also be reserved due to its low ESR. It is
recommended to use three ceramic capacitors (100 nF, 33 pF, 10 pF) for composing the MLCC array,
and place these capacitors close to VBAT pins. 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 1 mm. In principle, the longer the VBAT trace is, the wider it will be.
In addition, to get a stable power source, it is suggested to use a TVS with low leakage current and
suitable reverse stand-off voltage, and also it is recommended to place it as close to the VBAT pins as
possible. The following figure shows the star structure of the power supply.
Figure 4: Star Structure of the Power Supply
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