668-0011 Rabbit Semiconductor, 668-0011 Datasheet - Page 24

• Manufacturer Part Number: 668-0011
• Description: IC MPU RABIT3000A 55.5MHZ128LQFP
• Manufacturer: Rabbit Semiconductor

Specifications of 668-0011

• Rohs Status: RoHS non-compliant
• Processor Type: Rabbit 3000 8-Bit
• Speed: 55.5MHz
• Voltage: 2.5V, 2.7V, 3V, 3.3V
• Mounting Type: Surface Mount
• Package / Case: 128-LQFP
• Features: -
• Other names: 316-1043

When the clock doubler is used and there is no subsequent division of the clock, the output
clock will be asymmetric, as shown in Figure 2-3.
The doubled-clock low time is subject to wide (50%) variation since it depends on process
parameters, temperature, and voltage. The times given above are for a core supply voltage
of 3.3 V and a temperature of 25°C. The doubled-clock low time increases by 20% when
the voltage is reduced to 2.5 V, and increases by about 40% when the voltage is reduced
further to 2.0 V. The values increase or decrease by 1% for each 5°C increase or decrease
in temperature. The doubled clock is created by xor’ing the delayed and inverted clock
with itself. If the original clock does not have a 50-50 duty cycle, then alternate clocks will
have a slightly different length. Since the duty cycle of the built-in oscillator can be as
14
Oscillator delayed
Example
Write
Cycle
Example
Read
Cycle
Doubled clock
and inverted
Delay
time
Oscillator
Address / CS
Address / CS
Early output enb
option
Early write pulse
option
Write pulse
Output enb
Figure 2-3. Effect of Clock Doubler
Data out
0.48P
48%
P
52%
0.52P
0.48P
Rabbit 3000 Microprocessor User’s Manual
0.52P
Data out from mem