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L850-GL Hardware User Manual Page 22 of 54
The filter capacitor design for power supply as 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 100~200uF
1uF, 100nF Digital signal noise
Filter out the interference generated from the clock
and digital signals
39pF, 33pF
700/800, 850/900 MHz
frequency band
Filter out low frequency band RF interference
18pF, 8.2pF,
6.8pF
1500/1700/1800/1900,
2100/2300,
2500/2600MHzfrequency
band
Filter out medium/high frequency band RF
interference
The stable power supply can ensure the normal operation of L850 module; and the ripple of the power
supply should be less than 300mV in design. When the module operates with the maximum emission
power, the maximum operating current can reach 1000mA, 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
3.2.2 Logic level
The L850module 1.8V logic level definition as shown in the following table:
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