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L816-AM Hardware User Manual
Page 20 of 42
The filter capacitor design for power supply is shown in the following table:
Recommended
capacitance
Application
Description
220uF x 2
Voltage-stabilizing capacitors
Reduce power fluctuations of the module in
operation, requiring capacitors with low ESR
LDO or DC/DC power supply requires the
capacitor of no less than 440uF
The capacitor for battery power supply
can be reduced to 100
~
220uF
1uF,100nF
Digital signal noise
Filter out the interference generated from the
clock and digital signals
39pF,33pF
850/900 MHz frequency band
Filter out low frequency band RF interference
18pF,8.2pF,6.8pF
1800/1900,2100MHz frequency
band
Filter out medium/high frequency band RF
interference
The stable power supply can ensure the normal operation of L816-AM module; and the ripple of the
power supply should be less than 165mV in design. When the module operates under GSM mode (Burst
transmit), the maximum operating current can reach 2A, so the power source should be not lower than
3.135V, or the module may shut down or reboot. The power supply limits are shown in Figure 3-3:
Figure 3-3 Power Supply Limit