PIC18F4520ESLASHMLQTP datasheet(42/390 Pages) MICROCHIP

42 / 390 page

PIC18F2420/2520/4420/4520

DS39631A-page 40

 2004 Microchip Technology Inc.

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 LP, XT,

HS or HSPLL 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 (RC, EC and INTIO

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)

Clock Source

before Wake-up

Clock Source

after Wake-up

Exit Delay

Clock Ready Status

Bit (OSCCON)

Primary Device Clock

(PRI_IDLE mode)

LP, XT, HS

TCSD(1)

OSTS

HSPLL

EC, RC

INTOSC(2)

IOFS

T1OSC or INTRC(1)

LP, XT, HS

TOST(3)

OSTS

HSPLL

TOST + trc

(3)

EC, RC

TCSD(1)

INTOSC(1)

TIOBST(4)

IOFS

INTOSC(2)

LP, XT, HS

TOST(4)

OSTS

HSPLL

TOST + trc

(3)

EC, RC

TCSD(1)

INTOSC(1)

None

IOFS

None

(Sleep mode)

LP, XT, HS

TOST(3)

OSTS

HSPLL

TOST + trc

(3)

EC, RC

TCSD(1)

INTOSC(1)

TIOBST(4)

IOFS

Note 1:

TCSD (parameter 38) 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”). On Reset, INTOSC defaults to 1 MHz.

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

TOST is the Oscillator Start-up Timer (parameter 32). trc is the PLL Lock-out Timer (parameter F12); it is

also designated as TPLL.

Execution continues during TIOBST (parameter 39), the INTOSC stabilization period.

PIC18F4520E/MLQTP Datasheet(PDF) 42 Page - Microchip Technology

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