20-101-1217 Rabbit Semiconductor, 20-101-1217 Datasheet - Page 120

• Manufacturer Part Number: 20-101-1217
• Description: MODULE RABBITCORE RCM3229
• Manufacturer: Rabbit Semiconductor

Specifications of 20-101-1217

• Module/board Type: MPU Core Module
• For Use With/related Products: RCM3229
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 316-1146

The drain on the battery by the RCM3200 is typically 12 µA when no other power is sup-
plied. If a 165 mA·h battery is used, the battery can last almost 2 years:
The actual life in your application will depend on the current drawn by components, not
on the RCM3200 and the storage capacity of the battery. The RCM3200 does not drain the
battery while it is powered up normally.
Cycle the main power off/on on the RCM3200 after you install a backup battery for the
first time, and whenever you replace the battery. This step will minimize the current drawn
by the real-time clock oscillator circuit from the backup battery should the RCM3200
experience a loss of main power.
Rabbit’s Technical Note TN235, External 32.768 kHz Oscillator Circuits, provides addi-
tional information about the current draw by the the real-time clock oscillator circuit.
D.1.2 Battery-Backup Circuit
Figure D-2 shows the battery-backup circuit.
The battery-backup circuit serves three purposes:
• It reduces the battery voltage to the SRAM and to the real-time clock, thereby limiting
• It ensures that current can flow only out of the battery to prevent charging the battery.
• A voltage, VOSC, is supplied to U5, which keeps the 32.768 kHz oscillator working
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the current consumed by the real-time clock and lengthening the battery life.
when the voltage begins to drop.
NOTE: Remember to cycle the main power off/on any time the RCM3200 is removed
from the Protoyping Board or motherboard since that is where the backup battery
would be located.
Figure D-2. RCM3200 Backup Battery Circuit
165 mA·h
----------------------- -
12 µA
W
=
1.6 years.
W
W
RabbitCore RCM3200