668-0003-C Rabbit Semiconductor, 668-0003-C Datasheet - Page 155

• Manufacturer Part Number: 668-0003-C
• Description: IC CPU RABBIT2000 30MHZ 100PQFP
• Manufacturer: Rabbit Semiconductor

Specifications of 668-0003-C

• Rohs Status: RoHS non-compliant
• Processor Type: Rabbit 2000 8-Bit
• Speed: 30MHz
• Voltage: 2.7V, 3V, 3.3V, 5V
• Mounting Type: Surface Mount
• Package / Case: 100-MQFP, 100-PQFP
• Features: -
• Other names: 316-1004; 668-0003

14. R
2000 C
ABBIT
LOCKS
The Rabbit 2000 has two built-in oscillators. The 32.768 kHz clock oscillator is needed
for the battery-backable clock, the watchdog timer, and the cold-boot function. The main
oscillator provides the run-time clock for the microprocessor. Figure 14-1 shows these
oscillator circuits.
W
W
W
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Figure 14-1. Rabbit 2000 Oscillator Circuits
The 32.768 kHz oscillator is slow to start oscillating after power-on. For this reason, a
wait loop in the BIOS waits until this oscillator is oscillating regularly before continuing
the startup procedure. If the clock is battery-backed, there will be no startup delay since
the oscillator is already oscillating. The startup delay may be as much as 5 seconds. Crys-
tals with low series resistance (R < 35 kΩ) will start faster. The required oscillator circuit
is shown in Figure 14-1(a).
Improvements were made in revisions A–C to reduce the internal power consumption of
the RTC circuit. In addition, external circuitry was introduced to further reduce the oscilla-
tor power consumption in board-level products based on the Rabbit 2000. Refer to
Section B.2.4 for more information.
Chapter 14 Rabbit 2000 Clocks
149