Datasheet

 2001-2013 Microchip Technology Inc. DS39598F-page 129
PIC16F818/819
FIGURE 15-4: EXTERNAL CLOCK TIMING
OSC1
CLKO
Q4 Q1 Q2 Q3 Q4 Q1
1
2
3
3
4
4
TABLE 15-1: EXTERNAL CLOCK TIMING REQUIREMENTS
Param
No.
Sym Characteristic Min Typ† Max Units Conditions
F
OSC External CLKI Frequency (Note 1) DC — 1 MHz XT and RC Oscillator mode
DC — 20 MHz HS Oscillator mode
DC — 32 kHz LP Oscillator mode
Oscillator Frequency (Note 1) DC — 4 MHz RC Oscillator mode
0.1 — 4 MHz XT Oscillator mode
4
5
—
—
20
200
MHz
kHz
HS Oscillator mode
LP Oscillator mode
1T
OSC External CLKI Period (Note 1) 1000 — — ns XT and RC Oscillator mode
50 — — ns HS Oscillator mode
5 — — ms LP Oscillator mode
Oscillator Period (Note 1) 250 — — ns RC Oscillator mode
250 — 10,000 ns XT Oscillator mode
50 — 250 ns HS Oscillator mode
5 — — ms LP Oscillator mode
2T
CY Instruction Cycle Time (Note 1) 200 TCY DC ns TCY = 4/FOSC
3TOSL,
T
OSH
External Clock in (OSC1) High
or Low Time
500 — — ns XT Oscillator
2.5 — — ms LP Oscillator
15 — — ns HS Oscillator
4T
OSR,
T
OSF
External Clock in (OSC1) Rise or
Fall Time
— — 25 ns XT Oscillator
— — 50 ns LP Oscillator
— — 15 ns HS Oscillator
† Data in “Typ” column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance
only and are not tested.
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 consumption. All devices are tested to operate at “min.”
values with an external clock applied to the OSC1/CLKI pin. When an external clock input is used, the
“max.” cycle time limit is “DC” (no clock) for all devices.