PIC18F4550ESPQTP datasheet(45/438 Pages) MICROCHIP

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DS39632E-page 43

PIC18F2455/2550/4455/4550

3.5.4

EXIT WITHOUT AN OSCILLATOR

START-UP DELAY

Certain exits from power-managed modes do not

invoke the OST at all. There are two cases:

• PRI_IDLE mode, where the primary clock source

is not stopped; and

• the primary clock source is not any of the XT or

HS modes.

In these instances, the primary clock source either

does not require an oscillator start-up delay, since it is

already running (PRI_IDLE), or normally does not

require an oscillator start-up delay (EC and any internal

oscillator modes). However, a fixed delay of interval

TCSD following the wake event is still required when

leaving Sleep and Idle modes to allow the CPU to

prepare for execution. Instruction execution resumes

on the first clock cycle following this delay.

TABLE 3-2:

EXIT DELAY ON WAKE-UP BY RESET FROM SLEEP MODE OR ANY IDLE MODE

(BY CLOCK SOURCES)

Microcontroller Clock Source

Exit Delay

Clock Ready Status

Bit (OSCCON)

Before Wake-up

After Wake-up

Primary Device Clock

(PRI_IDLE mode)

XT, HS

None

OSTS

XTPLL, HSPLL

INTOSC(3)

IOFS

T1OSC or INTRC(1)

XT, HS

TOST(4)

OSTS

XTPLL, HSPLL

TOST + trc(4)

TCSD(2)

INTOSC(3)

TIOBST(5)

IOFS

INTOSC(3)

XT, HS

TOST(4)

OSTS

XTPLL, HSPLL

TOST + trc(4)

TCSD(2)

INTOSC(3)

None

IOFS

None

(Sleep mode)

XT, HS

TOST(4)

OSTS

XTPLL, HSPLL

TOST + trc(4)

TCSD(2)

INTOSC(3)

TIOBST(5)

IOFS

Note 1:

In this instance, refers specifically to the 31 kHz INTRC clock source.

TCSD (parameter 38, Table 28-12) is a required delay when waking from Sleep and all Idle modes and runs

concurrently with any other required delays (see Section 3.4 “Idle Modes”).

Includes both the INTOSC 8 MHz source and postscaler derived frequencies.

TOST is the Oscillator Start-up Timer period (parameter 32, Table 28-12). trc is the PLL lock time-out

(parameter F12, Table 28-9); it is also designated as TPLL.

Execution continues during TIOBST (parameter 39, Table 28-12), the INTOSC stabilization period.

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