Datasheet

© 2007-2012 Microchip Technology Inc. DS70293G-page 63
PIC24HJ32GP302/304, PIC24HJ64GPX02/X04 AND PIC24HJ128GPX02/X04
6.3 System Reset
The PIC24HJ32GP302/304, PIC24HJ64GPX02/X04
and PIC24HJ128GPX02/X04 family of devices have
two types of Reset:
• Cold Reset
• Warm Reset
A cold Reset is the result of a Power-on Reset (POR)
or a Brown-out Reset (BOR). On a cold Reset, the
FNOSC configuration bits in the FOSC device
configuration register selects the device clock source.
A warm Reset is the result of all other reset sources,
including the RESET instruction. On warm Reset, the
device will continue to operate from the current clock
source as indicated by the Current Oscillator Selection
bits (COSC<2:0>) in the Oscillator Control register
(OSCCON<14:12>).
The device is kept in a Reset state until the system
power supplies have stabilized at appropriate levels
and the oscillator clock is ready. A description of the
sequence in which this occurs and is shown in
Figure 6-2.
TABLE 6-1: OSCILLATOR DELAY
Oscillator Mode
Oscillator
Startup Delay
Oscillator Startup
Timer
PLL Lock Time Total Delay
FRC, FRCDIV16,
FRCDIVN
T
OSCD ——TOSCD
FRCPLL TOSCD —TLOCK TOSCD + TLOCK
XT TOSCD TOST —TOSCD + TOST
HS TOSCD TOST —TOSCD + TOST
EC ————
XTPLL T
OSCD TOST TLOCK TOSCD + TOST + TLOCK
HSPLL TOSCD TOST TLOCK TOSCD + TOST + TLOCK
ECPLL — — TLOCK TLOCK
SOSC TOSCD TOST —TOSCD + TOST
LPRC TOSCD ——TOSCD
Note 1: TOSCD = Oscillator Start-up Delay (1.1 μs max for FRC, 70 μs max for LPRC). Crystal Oscillator start-up
times vary with crystal characteristics, load capacitance, etc.
2: T
OST = Oscillator Start-up Timer Delay (1024 oscillator clock period). For example, TOST = 102.4 μs for a
10 MHz crystal and TOST = 32 ms for a 32 kHz crystal.
3: T
LOCK = PLL lock time (1.5 ms nominal), if PLL is enabled.