3 Application Interface
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Figure 4. Power supply design
The filter capacitor design for power supply as shown in the following table:
Table 8. The filter capacitor design for power supply
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 with no less than 440uF
in the power supply voltage range.
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, 10pF,
1500/1800, 2100/2300,
Filter out medium/high frequency band