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Appendix C provides information on the current requirements of
the RCM5400W, and includes some background on the chip
select circuit used in power management.
C.1 Power Supplies
The RCM5400W requires a regulated 3.3 V DC ±5% power source. The RabbitCore
design presumes that the voltage regulator is on the user board, and that the power is made
available to the RCM5400W board through header J1.
An RCM5400W with no loading at the outputs operating at 73.73 MHz typically draws
125 mA, and may draw up to 625 mA while the Wi-Fi circuit is transmitting or receiving.
C.1.1 Battery-Backup
The RCM5400W does not have a battery, but there is provision for a customer-supplied
battery to back up the data SRAM and keep the internal Rabbit 5000 real-time clock
running.
Header J1, shown in Figure C-1, allows access to the external battery. This header makes
it possible to connect an external 3 V power supply. This allows the SRAM and the inter-
nal Rabbit 5000 real-time clock to retain data with the RCM5400W powered down.
A battery with a nominal voltage of 3 V and a minimum capacity of 165 mA·h is recom-
mended. A lithium battery is strongly recommended because of its nearly constant
nominal voltage over most of its life.
OEM User's Manual
A
PPENDIX
VIN
1
External
Battery
VBAT_EXT
7
Figure C-1. External Battery Connections
at Header J1
C. P
OWER
J1
GND
2
8
S
UPPLY
105
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