20-101-0356 Rabbit Semiconductor, 20-101-0356 Datasheet - Page 90

• 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

Transistors Q20 and Q21 are of opposite polarity so that a rail-to-rail voltages can be
passed. When the /CS1 voltage is low, Q20 will conduct. When the /CS1 voltage is high,
Q21 will conduct. It takes time for the transistors to turn on, creating a propagation delay.
This delay is typically very small, about 10 ns to 15ns.
The signal that turns the transistors on is a high on the processor’s reset line, /RES. When
the Jackrabbit is not in reset, the reset line will be high, turning on N-channel Q20 and
Q22. Q22 is a simple inverter needed to turn on Q21, an P-channel MOSFET. When a
reset occurs, the /RES line will go low. This will cause C23 to discharge through R42 and
R40. This small delay (about 160 µs) ensures that there is adequate time for the processor
to write any last byte pending to the SRAM before the processor puts itself into a reset
state. When coming out of reset, CS will be enabled very quickly because D20 conducts to
charge capacitor C23.
86
Jackrabbit (BL1800)