101-0412 Rabbit Semiconductor, 101-0412 Datasheet - Page 73

• Manufacturer Part Number: 101-0412
• Description: INTERFACE PROG 12KEY DISP OP6700
• Manufacturer: Rabbit Semiconductor

Specifications of 101-0412

• Module/board Type: Single Board Computer Module
• For Use With/related Products: OP6700
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Figure C-3 shows the battery-backup circuitry on the Intellicom board.
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 U13, which keeps the 32.768 kHz oscillator working
VRAM and Vcc are nearly equal (<100 mV, typically 10 mV) when power is supplied to
the Intellicom. VRAM is also available on pin 34 of header J2 to facilitate battery backup
of the external circuit. Note that the recommended minimum resistive load at VRAM is
100 kΩ, and new battery life calculations should be done to take external loading into
account.
C.2.2 Power to VRAM Switch
The VRAM switch, shown in Figure C-4, allows the battery backup to provide power
when the external power goes off. The switch provides an isolation between Vcc and the
battery when Vcc goes low. This prevents the Vcc line from draining the battery.
User’s Manual
the current consumed by the real-time clock and lengthening the battery life.
when the voltage begins to drop.
Figure C-3. Intellicom Battery-Backup Circuit
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thermistor
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