20-668-0024 Rabbit Semiconductor, 20-668-0024 Datasheet - Page 324

• Manufacturer Part Number: 20-668-0024
• Description: IC CPU RABBIT4000 128-LQFP
• Manufacturer: Rabbit Semiconductor

Specifications of 20-668-0024

• Processor Type: Rabbit 4000 8-bit
• Speed: 60MHz
• Voltage: 2.5V, 2.7V, 3V, 3.3V
• Mounting Type: Surface Mount
• Package / Case: 128-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Other names: 20-668-0022; 316-1078

28.4 Clock Speeds
28.4.1 Recommended Clock/Memory Configurations
The preferred configuration for a Rabbit-based system is to use an external crystal or reso-
nator that has a frequency one-half of the maximum internal clock frequency. The oscillator
frequency can be doubled or divided by 2, 4, 6, or 8, giving a variety of operating speeds
from the same crystal frequency. In addition, the 32.768 kHz oscillator that drives the
battery-backable clock can be used as the main processor clock and, to save the substantial
power consumed by the fast oscillator, the fast oscillator can be turned off. This scenario is
called the sleepy mode, where the clock speed is from 2 kHz to 32 kHz, and the operating
system current consumption of 10 to 120 µA depends on frequency and voltage.
Table 28-10 describes some recommended clock and memory configurations for both
8-bit and 16-bit memory devices. Optimal configurations for using 15 ns, 45–55 ns, and
70 ns memories are shown. Note that there is always at least one wait state in the 16-bit
mode.
The Rabbit 4000 is rated for a minimum clock period of 16 ns for both commercial and
industrial specifications (preliminary). The commercial rating calls for a ±5% voltage
variation from 3.3 V, and a temperature range from -40 to + 70°C. The industrial ratings
stretch the voltage variation to ±10% over a temperature range from -40 to + 85°C. This
corresponds to maximum clock frequencies of about 60 MHz (commercial or industrial).
If the clock doubler or spectrum spreader is used, these maximum ratings must be reduced
as shown in Table 28-11.
314
Frequency
29.4912
18.4320
14.7456
22.1184
11.0592
(MHz)
Input
Frequency
Table 28-10. Recommended Clock/Memory Configurations
Internal
58.9824
44.2368
36.8640
29.4912
22.1184
(MHz)
16 bits, 45–55 ns,
8 bits, 45–55 ns,
Recommended Memory Setup
16 bits, 70 ns,
8 bits, 15 ns,
8 bits, 15 ns,
8 bits, 70 ns,
0 wait states
0 wait states
0 wait states
0 wait states
1 wait state
1 wait state
SRAM
16 bits, 45–55 ns,
8 bits, 45–55 ns,
8 bits, 45–55 ns,
8 bits, 45–55 ns,
16 bits, 70 ns,
8 bits, 70 ns,
2 wait states
0 wait states
0 wait states
1 wait state
1 wait state
1 wait state
Flash
Rabbit 4000 Microprocessor User’s Manual
Fastest 8-bit configuration
without wait states
(run code from SRAM)
Fastest 16-bit, 55 ns configuration
without additional wait states
Fastest 8-bit, 55 ns configuration
with 1 wait state
(run code in SRAM)
Fastest 16-bit, 70 ns configuration
without additional wait states
Fastest 8-bit, 55 ns configuration
without wait states
Fastest 8-bit, 70 ns configuration
without wait states
Use