RCM2000 datasheet(67/80 Pages) DIGI

67 / 80 page

User’s Manual

APPENDIX C. POWER MANAGEMENT

Appendix C describes the RCM2000 power circuitry.

C.1 Power Supplies

The RCM2000 requires a regulated 5 V ± 0.25 V DC power source.

An RCM2000 with no loading at the outputs operating at 18.432 MHz typically draws 88 mA,

and an RCM2000 operating at 25.8048 MHz typically draws 120 mA. The RCM2000 will

consume 13 mA to 15 mA of additional current when the programming cable is used to

connect J3 to a PC.

C.1.1 Batteries and External Battery Connections

The RCM2000 does not have a battery, but there is provision for a customer-supplied bat-

tery to back up SRAM and keep the internal Rabbit 2000 real-time clock running.

Header J2, 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 2000 real-time clock to retain data with the RCM2000 powered down.

Figure C-1. External Battery Connections at Header J2

A lithium battery with a nominal voltage of 3 V and a minimum capacity of 165 mA·h is

recommended. A lithium battery is strongly recommended because of its nearly constant

nominal voltage over most of its life.

VCC

VRAM

GND

VBAT

External

Battery

RCM2000 Datasheet(PDF) 67 Page - Digi International Inc.