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3.3. Power Supply
The following table shows pin definition of VCC pins and ground pins.
Table 7: Definition of VCC and GND Pins
Pin No.
2, 4, 70, 72, 74
3, 5, 11, 27, 33, 39, 45, 51,
57, 71, 73
3.3.1. Decrease Voltage Drop
The power supply range of the module is from 3.135 V to 4.4 V. Please ensure that the input voltage will
never drop below 3.135 V, otherwise the module will be powered off automatically. The voltage ripple of
the input power supply should to be less than 100 mV, and the maximum voltage drop should be less than
165 mV, as shown by the following figure.
VCC 3.7 V
Voltage Drop < 165 mV
Figure 5: Power Supply Limits During Radio Transmission
Ensure the continuous current capability of the power supply is 3.0 A. To decrease the voltage drop, two
energy storage capacitor of about 220 µF with low ESR (ESR = 0.7 Ω) should be used, and a multi-layer
ceramic chip capacitor (MLCC) array should also be used due to its ultra-low ESR. It is recommended to
use four ceramic capacitors (1 µF, 100 nF, 33 pF, 10 pF) for composing the MLCC array, and place these
capacitors close to VCC pins. The width of VCC trace should be no less than 2.5 mm. In principle, the
longer the VCC trace is, the wider it should be.
In addition, to guarantee stability of the power supply, please use a zener diode with a reverse zener
voltage of 5.1 V and a dissipation power of higher than 0.5 W. The following figure shows a reference
circuit for the VCC.
RM502Q-GL_Hardware_Design
Pin Name
VCC
GND
Burst Transmission
RM502Q-GL Hardware Design
I/O
Description
PI
Power Supply
-
Ground
Burst Transmission
5G Module Series
DC Characteristics
3.135–4.4 V
3.7 V typical DC supply
-
Voltage Ripple
< 100 mV
27 / 83
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