Requirements For Voltage Stability - Quectel UMTS Series Hardware Design

⚫
NOTE
1. If you use the module that does not support the GSM band, a power supply capable of providing at
least 2 A can be used in the design.
2. It is recommended to design switch control for power supply.

3.4.3. Requirements for Voltage Stability

The power supply range of the module is from 3.4 V to 4.5 V. Please make sure the input voltage will
never drop below 3.4 V.
VBAT
Figure 7: Power Supply Limits during Burst Transmission
To decrease voltage drop, a bypass capacitor of about 100 µF with low ESR (ESR = 0.7 Ω) should be
used, and a multi-layer ceramic chip (MLCC) capacitor array should also be reserved due to its ultra-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 the VBAT_BB and VBAT_RF 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_BB trace should be no less than 1 mm; and the width of VBAT_RF trace
should be no less than 2 mm. In principle, the longer the VBAT trace is, the wider it will be.
In addition, in order to ensure the stability of power source, it is suggested that a TVS diode of which
reverse stand-off voltage is 4.7 V and peak pulse power is up to 2550 W should be used. The following
figure shows the star structure of the power supply.
UC200A-GL_Hardware_Design
Burst
Transmission
Drop
UMTS/HSPA+ Module Series
Burst
Transmission
Ripple
28 / 78