Power Supply; Power Supply Pins; Decrease Voltage Drop - Quectel SC200R Series Hardware Design

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Smart Module Series

3.4. Power Supply

SC200R series module provides two VBAT_RF pins and two VBAT_BB pins for connection with the

external power supply. The VBAT_RF pins are used for the RF part of the module and the VBAT_BB pins

are used for the baseband part of the module.

The power supply range of the module is 3.55–4.2 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 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

3.1 V and as a result the module powers off automatically. Therefore, make sure the input voltage never

drops below 3.1 V.

3 A

Input current

3.8 V

Voltage

3.1 V

Figure 2: 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_BB/VBAT_RF 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, in order to get a stable power source, it is suggested to use a TVS and place it as close to the

VBAT_BB/VBAT_RF pins as possible to enhance surge protection. The following figure shows the star

structure of the power supply.

SC200R&SC262R_Series_Hardware_Design

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Sc262r series