DVR datasheet(84/416 Pages) MICROCHIP

部件名	DVR

功能描述	16-Bit General Purpose Microcontrollers with 256-Kbyte Flash and 16-Kbyte RAM in Low Pin Count Packages

PDF	416 Pages

Scroll/Zoom	100%

制造商	MICROCHIP [Microchip Technology]

网页	http://www.microchip.com

标志

84 / 416 page

PIC24FJ256GA705 FAMILY

DS30010118D-page 84

 2016-2018 Microchip Technology Inc.

7.4.1

POR AND LONG OSCILLATOR

START-UP TIMES

The oscillator start-up circuitry and its associated delay

timers are not linked to the device Reset delays that

occur at power-up. Some crystal circuits (especially low-

frequency crystals) will have a relatively long start-up

time. Therefore, one or more of the following conditions

is possible after SYSRST is released:

• The oscillator circuit has not begun to oscillate.

• The Oscillator Start-up Timer has not expired (if a

crystal oscillator is used).

• The PLL has not achieved a lock (if PLL is used).

The device will not begin to execute code until a valid

clock source has been released to the system. There-

fore, the oscillator and PLL start-up delays must be

considered when the Reset delay time must be known.

7.4.2

FAIL-SAFE CLOCK MONITOR

(FSCM) AND DEVICE RESETS

If the FSCM is enabled, it will begin to monitor the

system clock source when SYSRST is released. If a

valid clock source is not available at this time, the

device will automatically switch to the FRC Oscillator

and the user can switch to the desired crystal oscillator

in the Trap Service Routine (TSR).

DVR 数据表(PDF) 84 Page - Microchip Technology