20-668-0011 Rabbit Semiconductor, 20-668-0011 Datasheet - Page 254

• Manufacturer Part Number: 20-668-0011
• Description: IC MPU RABIT3000A 55.5MHZ128LQFP
• Manufacturer: Rabbit Semiconductor

Specifications of 20-668-0011

• 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
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 55.5 MHz
• Operating Supply Voltage: 1.8 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 55 C
• Number Of Programmable I/os: 56
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 316-1061

The access time is given by
Similarly, the gross output-enable access time is T + minimum clock low time (it is
assumed that the early output enable option is enabled). This is reduced by the spectrum
spreader loss, the time from clock to output for the output enable signal, the data setup
time, and a correction for the asymmetry of the original oscillator clock.
Example Output-Enable Access Time Calculation
• clock = 29.49 MHz, so T = 34 ns
• operating voltage is 3.3 V
• the clock doubler has a nominal delay of 16 ns (see Table 27-8), resulting in a minimum
• clock to output enable is 5 ns (assuming 20 pF load)
• spectrum spreader is on in normal mode, resulting in a loss of 3 ns worst-case (see
• main clock asymmetry is 52% / 48%, resulting in a loss of 4% of the clock period, or
The output enable access time is given by
244
clock low time of 80% × 16 ns = 12.8 ns
Table 27-9)
1.4 ns
NOTE: There is some process and temperature variation in the clock doubler settings. As
a rule of thumb, a 20% variation should be considered. When the doubler is enabled,
80% of the nominal value should be used for the memory access time calculation.
access time
access time
= 2T - (clock to address) - (data setup) - (spreader delay)
= 68 ns - 8 ns - 1 ns - 3 ns
= 56 ns
= T + (min. clock low) - (clock to output enable) -
= 34 ns + 12.8 ns - 5 ns - 3 ns - 1.4 ns - 1 ns
= 36 ns
(spreader delay) - (asymmetry delay) - (data setup time)
Rabbit 3000 Microprocessor User’s Manual