Datasheet

 2010 Microchip Technology Inc. DS39616D-page 351
PIC18F2331/2431/4331/4431
FIGURE 26-9: TIMER0 AND TIMER1 EXTERNAL CLOCK TIMINGS
TABLE 26-9: TIMER0 AND TIMER1 EXTERNAL CLOCK REQUIREMENTS
Param
No.
Symbol Characteristic Min Max Units Conditions
40 Tt0H T0CKI High Pulse Width No prescaler 0.5 T
CY + 20 — ns VDD = 2V
With prescaler 10 — ns
41 Tt0L T0CKI Low Pulse Width No prescaler 0.5 T
CY + 20 — ns
With prescaler 10 — ns
42 Tt0P T0CKI Period No prescaler T
CY + 10 — ns
With prescaler Greater of:
20 ns or T
CY + 40
N
— ns N = prescale value
(1, 2, 4,..., 256)
45 Tt1H T1CKI High
Time
Synchronous, no prescaler 0.5 T
CY + 20 — ns
Synchronous,
with prescaler
PIC18FXX31 10 — ns
PIC18LFXX31 25 — ns
Asynchronous PIC18FXX31 30 — ns
PIC18LFXX31 50 — ns
46 Tt1L T1CKI
Low Time
Synchronous, no prescaler 0.5 T
CY + 5 — ns
Synchronous,
with prescaler
PIC18FXX31 10 — ns
PIC18LFXX31 25 — ns
Asynchronous PIC18FXX31 30 — ns
PIC18LFXX31 50 — ns
47 Tt1P T1CKI Input
Period
Synchronous Greater of:
20 ns or T
CY + 40
N
— ns N = prescale value
(1, 2, 4, 8)
Asynchronous 60 — ns
Ft1 T1CKI Oscillator Input Frequency Range DC 50 kHz
48 Tcke2tmrI Delay from External T1CKI Clock Edge to
Timer Increment
2 T
OSC 7 TOSC —
46
47
45
48
41
42
40
T0CKI
T1OSO/T1CKI
TMR0 or TMR1