PIC18F258 Datasheet, PDF (341/384 Pages) Microchip Technology – High Performance, 28/40-Pin Enhanced FLASH Microcontrollers with CAN

PIC18FXX8
FIGURE 27-7:
RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER AND POWER-UP
TIMER TIMING
VDD
MCLR
Internal
POR
PWRT
Time-out
OSC
Time-out
Internal
Reset
Watchdog
Timer
Reset
33
32
I/O Pins
Note: Refer to Figure 27-4 for load conditions.
30
31
34
34
FIGURE 27-8:
VDD
VIRVST
BROWN-OUT RESET AND LOW VOLTAGE DETECT TIMING
BVDD (for 35)
VLVD (for 37)
35, 37
VBGAP = 1.2V
Enable Internal Reference Voltage
Internal Reference Voltage stable
36
TABLE 27-9: RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER, POWER-UP TIMER,
BROWN-OUT RESET AND LOW VOLTAGE DETECT REQUIREMENTS
Param
No.
Symbol
Characteristic
Min
Typ
Max
Units
Conditions
30
TmcL MCLR Pulse Width (low)
2
—
—
µs
31
TWDT Watchdog Timer Time-out Period
(No Prescaler)
7
18
33
ms
32
TOST
Oscillation Start-up Timer Period
1024 TOSC — 1024 TOSC — TOSC = OSC1 period
33
TPWRT Power-up Timer Period
28
72
132
ms
34
TIOZ
I/O Hi-impedance from MCLR Low or
—
2
—
µs
Watchdog Timer Reset
35
TBOR Brown-out Reset Pulse Width
200
—
—
µs For VDD ≤ BVDD (see D005)
36
TIVRST Time for Internal Reference
Voltage to become stable
—
20
50
µs
37
TLVD
Low Voltage Detect Pulse Width
200
—
—
µs For VDD ≤ VLVD (see D420)
 2002 Microchip Technology Inc.
Preliminary
DS41159B-page 339