Datasheet
PIC17C4X
DS30412C-page 184 1996 Microchip Technology Inc.
Applicable Devices 42 R42 42A 43 R43 44
19.5 Timing Diagrams and Specifications
FIGURE 19-2: EXTERNAL CLOCK TIMING
TABLE 19-2: EXTERNAL CLOCK TIMING REQUIREMENTS
Param
No. Sym Characteristic Min Typ† Max Units Conditions
Fosc External CLKIN Frequency
(Note 1)
DC
DC
DC
DC
—
—
—
—
8
16
25
33
MHz
MHz
MHz
MHz
EC osc mode - 08 devices (8 MHz devices)
- 16 devices (16 MHz devices)
- 25 devices (25 MHz devices)
- 33 devices (33 MHz devices)
Oscillator Frequency
(Note 1)
DC
1
1
1
1
DC
—
—
—
—
—
—
4
8
16
25
33
2
MHz
MHz
MHz
MHz
MHz
MHz
RC osc mode
XT osc mode - 08 devices (8 MHz devices)
- 16 devices (16 MHz devices)
- 25 devices (25 MHz devices)
- 33 devices (33 MHz devices)
LF osc mode
1 Tosc External CLKIN Period
(Note 1)
125
62.5
40
30.3
—
—
—
—
—
—
—
—
ns
ns
ns
ns
EC osc mode - 08 devices (8 MHz devices)
- 16 devices (16 MHz devices)
- 25 devices (25 MHz devices)
- 33 devices (33 MHz devices)
Oscillator Period
(Note 1)
250
125
62.5
40
30.3
500
—
—
—
—
—
—
—
1,000
1,000
1,000
1,000
—
ns
ns
ns
ns
ns
ns
RC osc mode
XT osc mode - 08 devices (8 MHz devices)
- 16 devices (16 MHz devices)
- 25 devices (25 MHz devices)
- 33 devices (33 MHz devices)
LF osc mode
2T
CY Instruction Cycle Time
(Note 1)
121.2 4/Fosc DC ns
3 TosL,
TosH
Clock in (OSC1)
high or low time
10 ‡ — — ns EC oscillator
4 TosR,
TosF
Clock in (OSC1)
rise or fall time
— — 5 ‡ ns EC oscillator
† 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.
OSC1
OSC2 †
Q4
Q1 Q2
Q3 Q4 Q1
1
3
3
4
4
2
† In EC and RC modes only.