20-101-1105 Rabbit Semiconductor, 20-101-1105 Datasheet - Page 104

• Manufacturer Part Number: 20-101-1105
• Description: MODULE RCM4100 RABBITCORE
• Manufacturer: Rabbit Semiconductor

Specifications of 20-101-1105

• Module/board Type: MPU Core Module
• Data Bus Width: 8 bit
• For Use With/related Products: RCM4100
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 316-1121

The drain on the battery by the RCM4110 is typically 7.5 µA when no other power is sup-
plied. If a 165 mA·h battery is used, the battery can last about 2.5 years:
The actual battery life in your application will depend on the current drawn by components
not on the RCM4100 series of modules and on the storage capacity of the battery. The
RCM4100 series of modules does not drain the battery while it is powered up normally.
Cycle the main power off/on after you install a backup battery for the first time, and when-
ever you replace the battery. This step will minimize the current drawn by the real-time
clock oscillator circuit from the backup battery should the RCM4100 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 real-time clock oscillator circuit.
C.1.2 Battery-Backup Circuit
Figure C-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 U6, which keeps the 32.768 kHz oscillator working
C.1.3 Reset Generator
The RCM4100 series of modules uses a reset generator to reset the Rabbit 4000 micropro-
cessor when the voltage drops below the voltage necessary for reliable operation. The
100
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 RCM4100 is removed
165 mA·h
----------------------- -
7.5 µA
from the Prototyping Board or motherboard since that is where the backup battery
would be located.
=
Figure C-2. RCM4100 Backup Battery Circuit
2.5 years.
W
W
W
RabbitCore RCM4100