668-0003-C Rabbit Semiconductor, 668-0003-C Datasheet - Page 80

• 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

7.3 Clock Doubler
The clock doubler is provided to allow a lower frequency crystal to be used for the main
oscillator and to provide an added range of clock frequency adjustability. The clock dou-
bler is controlled via the Global Clock Double Register as shown in Table 7-2.
Table 7-3 lists the recommended values or “settings” for the Global Clock Double Register
for various oscillator frequencies.
74
7:3
2:0
Bit(s)
Table 7-3. Recommended Delays Set In GCDR for Clock Doubler
Table 7-2. Global Clock Double Register (GCDR, adr = 0x0F)
xxxxx
000
001
010
011
100
101
110
111
Value
Recommended GCDR Value
These bits are ignored.
The clock double circuit is disabled.
10 ns nominal low time.
12 ns nominal low time.
14 ns nominal low time.
16 ns nominal low time.
18 ns nominal low time.
20 ns nominal low time.
8 ns nominal low time.
7
6
5
4
3
2
1
0
12.9024–14.7576 MHz
14.7576–16.5888 MHz
16.5888–20.2752 MHz
20.2752–23.9616 MHz
23.9616–31.3344 MHz
11.0592–12.9024 MHz
Description
Frequency Range
Rabbit 2000 Microprocessor User’s Manual
≤11.0592 MHz
>31.3344 MHz