User’s Manual
157
APPENDIX D. POWER SUPPLY
Appendix D provides information on the current requirements
of the RCM3750, and includes some background on the chip
select circuit used in power management.
D.1 Power Supplies
Power is supplied from the motherboard to which the RCM3750 is connected via header
J1.
D.1.1 RCM3750
The RCM3750 has an onboard +3.3 V linear power regulator that provides the +3.3 V
supply to operate the microprocessor-related circuitry of the RCM3750.
Figure D-1 shows
the power-supply circuit.
Figure D-1. RCM3750 Power Supply
The RCM3750 requires a regulated 4.75 V to 5.25 V DC power source. An RCM3750 with
no loading at the outputs operating at 22.1 MHz typically draws 175 mA when the Ethernet
connection is active.
RCM3750 LINEAR POWER REGULATOR
POWER
IN
J1
10 F
LP8345/
MIC5209
+3.3 V
38
39
40
10 nF
+V
37 VBAT_EXT
External
Battery
10 F
1.5 W
U7/U4
10 nF