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Appendix D provides information on the current requirements
of the RCM3209/RCM3229, and includes some background on
the chip select circuit used in power management.
D.1 Power Supplies
The RCM3209/RCM3229 requires a regulated 3.3 V ± 0.15 V DC power source. The
RabbitCore design presumes that the voltage regulator is on the user board, and that the
power is made available to the RCM3209/RCM3229 board through header J62.
An RCM3209/RCM3229 with no loading at the outputs operating at 29.4 MHz typically
draws 145 mA. The RCM3209/RCM3229 will consume an additional 10 mA when the
programming cable is used to connect the programming header, J1, to a PC.
D.1.1 Battery Backup
The RCM3209/RCM3229 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 3000 real-time
clock running.
Header J62, shown in Figure D-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 3000 real-time clock to retain data with the RCM3209/RCM3229 powered
down.
User's Manual
A
PPENDIX
J62
VRAM
30
29
+3.3 VIN
31
32
Figure D-1. External Battery Connections
at Header J2
D. P
OWER
External
Battery
VBAT_EXT
GND
S
UPPLY
135
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