20-101-0356 Rabbit Semiconductor, 20-101-0356 Datasheet - Page 87

• Manufacturer Part Number: 20-101-0356
• Description: COMPUTER SINGLE-BOARD BL1800
• Manufacturer: Rabbit Semiconductor

Specifications of 20-101-0356

• Module/board Type: Single Board Computer Module
• Product: Modules
• Data Bus Width: 8 bit
• Processor Type: Rabbit 2000
• Sram: 128 KB
• Flash: 256 KB
• Timers: 8 bit, 10 bit
• Number Of I/os: 14
• Backup Battery: 3 V Lithium Coin Type
• Operating Voltage: 8 V to 40 V
• Power Consumption: 1.2 W
• Board Size: 89 mm x 64 mm x 19 mm
• Description/function: Computer Module
• For Use With/related Products: BL1800
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 316-1079

C.2.1 Battery Backup Circuit
Figure C-5 shows the Jackrabbit battery backup circuitry.
Resistor R12, shown in Figure C-5, is typically not stuffed on the Jackrabbit board.
VRAM and Vcc are equal when power is supplied to the Jackrabbit. R13 prevents any cat-
astrophic failure of Q1 from allowing unlimited current to enter the soldered-in battery.
Resistors R14 and R15 make up a voltage divider between the battery voltage and the tem-
perature-compensation voltage at the anode of diode D80. This voltage divider biases the
base of Q1 to about 2.6 V. V
These voltages vary with temperature. VRAM varies the least because temperature-com-
pensation diodes D80–D82 will offset the variation with temperature of Q1 V
R82 may be stuffed instead of the corresponding D80–D82 to provide the optimum tem-
perature compensation.
Resistor R10 provides a minimum load to the regulator circuit.
User’s Manual
Figure C-5. Jackrabbit Battery Backup Circuit
BE
on Q1 is about 0.55 V. Therefore, VRAM is about 2.05 V.
W
W
W
W
W
W
BE
. R80–
83