20-101-1094 Rabbit Semiconductor, 20-101-1094 Datasheet - Page 122

• Manufacturer Part Number: 20-101-1094
• Description: MCU RCM4000 RABBITCORE
• Manufacturer: Rabbit Semiconductor

Specifications of 20-101-1094

• Module/board Type: MPU Core Module
• Product: Microcontroller Modules
• Core Processor: Rabbit 4000
• Clock Speed: 58.98 MHz
• Interface Type: Ethernet, Serial
• Flash: 512 KB
• Timers: 10 x 8 bit, 1 x 10 bit, 1 x 16 bit
• Operating Supply Voltage: 3 V to 3.6 V
• Board Size: 47 mm x 61 mm x 20 mm
• Core: RCM4000
• Processor Series: RCM4000
• Cpu Core: Rabbit 4000
• For Use With/related Products: RCM4000
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 316-1139

The drain on the battery by the RCM4000 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 RCM4000 and on the storage capacity of the battery. The RCM4000 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 RCM4000 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 U8, 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 RCM4000 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. RCM4000 Backup Battery Circuit
2.5 years.
W
W
RabbitCore RCM4000