20-668-0003 Rabbit Semiconductor, 20-668-0003 Datasheet - Page 78

• Manufacturer Part Number: 20-668-0003
• Description: IC CPU RABBIT2000 30MHZ 100PQFP
• Manufacturer: Rabbit Semiconductor

Specifications of 20-668-0003

• 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
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 30 MHz
• Operating Supply Voltage: 0 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Number Of Programmable I/os: 40
• Number Of Timers: 8 & 10 bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 20-668-0003; 316-1062

7.2 Rabbit Oscillators and Clocks
There are two crystal oscillators built into the Rabbit. The main oscillator accepts crystals
up to a frequency of 29.4912 MHz (first overtone crystals only). The clock oscillator
requires a 32.768 kHz crystal, which is powered by VBAT, and can be battery-backed.
An external oscillator or clock can be substituted for either crystal by connecting the
external clock to XTALA1 or XTALB1 and leaving the other crystal pin (XTALA2 or
XTALB2) unconnected. If an external oscillator is used for the main clock the output pin
CLK (pin 1) should be used if the clock is needed externally. This signal is synchronized
with the internal clock. In comparison, the internal clock is delayed by approximately 10
nanoseconds compared to the external oscillator input XTALB1.
The main oscillator is normally used to derive the clock for the processor and peripherals.
The 32.768 kHz oscillator is normally used to clock the watchdog timer, the battery back-
able time/date clock, and the periodic interrupt. The main oscillator can be shut down in a
special low-power mode of operation, and the 32.768 kHz oscillator is then used to clock
all the things normally clocked by the main oscillator. This results in slower execution at
low power (~200 µA).
The on-chip routing of the clocks is shown in Figure 7-1. The main oscillator can be dou-
bled in frequency and/or divided by 8. If both doubling and dividing are enabled, then
there will be a net division by 4. The CPU clock can optionally by divided by 2 and then
optionally drive the external pin CLK. In many cases the clock is not needed externally,
and in that case CLK can be used as a general-purpose output pin. The divide-by-2 option
is available to minimize electromagnetic radiation if the is clock is driven off chip.
72
Main Osc
32 kHz
Osc
Note: Peripherals cannot be clocked slower than CPU.
DISABLE
To Watchdog Timer and
Time/Date Clock
Doubler
Clock
Figure 7-1. Clock Distribution
f/8
Rabbit 2000 Microprocessor User’s Manual
f or f/2
Peripheral
Devices
f/2
CPU
ext pin
CLK