PIC16F870/871
FIGURE 14-8: TIMER0 AND TIMER1 EXTERNAL CLOCK TIMINGS
RA4/T0CKI
41
40
42
RC0/T1OSO/T1CKI
46
45
47
48
TMR0 or
TMR1
Note: Refer to Figure 14-3 for load conditions.
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
0.5TCY + 20
—
—
ns Must also meet
parameter 42
With Prescaler
No Prescaler
With Prescaler
No Prescaler
10
0.5TCY + 20
10
—
—
—
—
—
—
—
—
—
—
ns
41*
42*
Tt0L
Tt0P
T0CKI Low Pulse Width
T0CKI Period
ns Must also meet
parameter 42
ns
ns
TCY + 40
With Prescaler Greater of:
20 or TCY + 40
ns N = prescale value
(2, 4, ..., 256)
N
0.5TCY + 20
15
45*
46*
47*
Tt1H
Tt1L
Tt1P
T1CKI High Time Synchronous, Prescaler = 1
—
—
—
—
—
—
ns Must also meet
parameter 47
Synchronous, Standard(F)
ns
ns
Prescaler =
2,4,8
Extended(LF)
25
Asynchronous Standard(F)
Extended(LF)
30
—
—
—
—
—
—
—
—
—
—
ns
ns
50
T1CKI Low Time
Synchronous, Prescaler = 1
Synchronous, Standard(F)
0.5TCY + 20
ns Must also meet
parameter 47
15
25
ns
ns
Prescaler =
2,4,8
Extended(LF)
Asynchronous Standard(F)
Extended(LF)
30
50
—
—
—
—
—
—
ns
ns
T1CKI input period Synchronous
Standard(F)
Greater of:
30 OR TCY + 40
ns N = prescale value
(1, 2, 4, 8)
N
Extended(LF) Greater of:
50 OR TCY + 40
N = prescale value
(1, 2, 4, 8)
N
Asynchronous Standard(F)
Extended(LF)
Timer1 oscillator input frequency range
(oscillator enabled by setting bit T1OSCEN)
60
—
—
—
—
—
ns
ns
100
DC
Ft1
200
kHz
48
*
TCKEZtmr1 Delay from external clock edge to timer increment
2Tosc
—
7Tosc
—
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.
1999 Microchip Technology Inc.
Preliminary
DS30569A-page 129
MICROCHIP [ MICROCHIP ]
