User's Manual

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L850-GL Hardware User Manual Page
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3.2 Power Supply
The power interface of L850 module as shown in the following table:
Pin
Pin Name
I/O
Pin Description
DC Parameter（V）
Minimum
Value
Typical
Value
Maximum
Value
2,4,70,72,74
+3.3V
PI
Power supply input
3.135
3.3
4.4
36
UIM_PWR
PO
USIM power supply
1.8V/3V
L850 module uses PCIe interface, according to the PCIe specification, the PCIe Vmain should be used as
the +3.3V power source, not the Vaux. The Vaux is the PCIe backup power source and it is not sufficient
as the power supply. In addition, the DC/DC power supply other than PCIe ports should not be used as
the external power cannot control the module status through the PCIe protocol.
3.2.1 Power Supply
The L850 module should be powered through the +3.3V pins, and the power supply design is shown in
Figure 3-2:
Figure 3-2 Power Supply Design
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