
PIC16F870/871
DS30569B-page 130
2003 Microchip Technology Inc.
FIGURE 14-8:
TIMER0 AND TIMER1 EXTERNAL CLOCK TIMINGS
TABLE 14-4:
TIMER0 AND TIMER1 EXTERNAL CLOCK REQUIREMENTS
Param
No.
Sym
Characteristic
Min
Typ
Max
Units
Conditions
40*
Tt0H
T0CKI High Pulse Width
No Prescaler
0.5 TCY + 20
—
ns
Must also meet
parameter 42
With Prescaler
10
—
ns
41*
Tt0L
T0CKI Low Pulse Width
No Prescaler
0.5 TCY + 20
—
ns
Must also meet
parameter 42
With Prescaler
10
—
ns
42*
Tt0P
T0CKI Period
No Prescaler
TCY + 40
—
ns
With Prescaler
Greater of:
20 or TCY + 40
N
—
ns
N = prescale value
(2, 4, ..., 256)
45*
Tt1H
T1CKI High Time
Synchronous, Prescaler = 1
0.5 TCY + 20
—
ns
Must also meet
parameter 47
Synchronous,
Prescaler = 2,4,8
Standard(F)15
—
ns
Extended(LF)25
—
ns
Asynchronous
Standard(F)30
—
ns
Extended(LF)50
—
ns
46*
Tt1L
T1CKI Low Time
Synchronous, Prescaler = 1
0.5 TCY + 20
—
ns
Must also meet
parameter 47
Synchronous,
Prescaler = 2,4,8
Standard(F)15
—
ns
Extended(LF)25
—
ns
Asynchronous
Standard(F)30
—
ns
Extended(LF)50
—
ns
47*
Tt1P
T1CKI input period Synchronous
Standard(F)
Greater of:
30 or TCY + 40
N
—
ns
N = prescale value
(1, 2, 4, 8)
Extended(LF)
Greater of:
50 or TCY + 40
N
N = prescale value
(1, 2, 4, 8)
Asynchronous
Standard(F)60
—
ns
Extended(LF)
100
—
ns
Ft1
Timer1 oscillator input frequency range
(oscillator enabled by setting bit T1OSCEN)
DC
—
200
kHz
48
TCKEZtmr1 Delay from external clock edge to timer increment
2 TOSC
—7 TOSC
—
*
These parameters are characterized but not tested.
Data in "Typ" column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested.
46
47
45
48
41
42
40
RA4/T0CKI
RC0/T1OSO/T1CKI
TMR0 or
TMR1