PIC17C75X
20.5
Timing Diagrams and Specifications
FIGURE 20-2: EXTERNAL CLOCK TIMING
Q4
Q3
3
Q4
3
Q1
4
Q1
Q2
OSC1
1
4
2
OSC2 †
† In EC and RC modes only.
TABLE 20-2: EXTERNAL CLOCK TIMING REQUIREMENTS
Param.
No.
Sym
Characteristic
Min Typ†
Max Units
Conditions
DC
DC
DC
—
—
—
8
25
33
MHz EC osc mode - 08 devices (8 MHz devices)
Fosc External CLKIN Frequency
MHz
MHz
- 25 devices (25 MHz devices)
- 33 devices (33 MHz devices)
(Note 1)
Oscillator Frequency
(Note 1)
DC
1
1
1
DC
—
—
—
—
—
4
8
25
33
2
MHz RC osc mode
MHz XT osc mode - 08 devices (8 MHz devices)
MHz
MHz
- 25 devices (25 MHz devices)
- 33 devices (33 MHz devices)
MHz LF osc mode
1
Tosc External CLKIN Period
125
40
30.3
—
—
—
—
—
—
ns
ns
ns
EC osc mode - 08 devices (8 MHz devices)
- 25 devices (25 MHz devices)
(Note 1)
- 33 devices (33 MHz devices)
Oscillator Period
(Note 1)
250
125
40
30.3
500
—
—
—
—
—
—
ns
ns
ns
ns
ns
RC osc mode
1,000
1,000
1,000
—
XT osc mode - 08 devices (8 MHz devices)
- 25 devices (25 MHz devices)
- 33 devices (33 MHz devices)
LF osc mode
2
3
4
TCY
Instruction Cycle Time
(Note 1)
121.2 4/Fosc
DC
ns
ns
ns
TosL, Clock in (OSC1)
TosH high or low time
10 ‡
—
—
—
—
EC oscillator
EC oscillator
TosR, Clock in (OSC1)
TosF rise or fall time
5 ‡
†
‡
Data in “Typ” column is at 5V, 25˚C unless otherwise stated. These parameters are for design guidance only and are not
tested.
These parameters are for design guidance only and are not tested, nor characterized.
Note 1: Instruction cycle period (TCY) equals four times the input oscillator time base period. All specified values are based on
characterization data for that particular oscillator type under standard operating conditions with the device executing code.
Exceeding these specified limits may result in an unstable oscillator operation and/or higher than expected current con-
sumption. All devices are tested to operate at “min.” values with an external clock applied to the OSC1/CLKIN pin.
When an external clock input is used, the “max.” cycle time limit is “DC” (no clock) for all devices.
DS30264A-page 232
Preliminary
1997 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
