PIC24FJ16MC101_12 Datasheet, PDF (66/350 Pages) Microchip Technology – 16-bit Microcontrollers (up to 32 KB Flash and 2 KB SRAM)

PIC24FJ16MC101/102 AND PIC24FJ32MC101/102/104
FIGURE 6-2:
SYSTEM RESET TIMING
VPOR
VVBbORor
VDD
1
POR
BOR
TPOR
2
SYSRST
Oscillator Clock
FSCM
Device Status
TBOR
3
TPWRT
4
TOSCD
TOST
Reset
TLOCK
6
TFSCM
5
Run
Time
1. POR: A POR circuit holds the device in Reset when the power supply is turned on. The POR circuit is active until VDD crosses the
VPOR threshold and the delay TPOR has elapsed.
2. BOR: The on-chip voltage regulator has a BOR circuit that keeps the device in Reset until VDD crosses the VBOR threshold and the
delay TBOR has elapsed. The delay TBOR ensures the voltage regulator output becomes stable.
3. PWRT Timer: The power-up timer continues to hold the processor in Reset for a specific period of time (TPWRT) after a BOR. The
delay TPWRT ensures that the system power supplies have stabilized at the appropriate level for full-speed operation. After the delay
TPWRT has elapsed, the SYSRST becomes inactive, which in turn enables the selected oscillator to start generating clock cycles.
4. Oscillator Delay: The total delay for the clock to be ready for various clock source selections are given in Table 6-1. Refer to
Section 8.0 “Oscillator Configuration” for more information.
5. When the oscillator clock is ready, the processor begins execution from location 0x000000. The user application programs a GOTO
instruction at the Reset address, which redirects program execution to the appropriate start-up routine.
6. The Fail-Safe Clock Monitor (FSCM), if enabled, begins to monitor the system clock when the system clock is ready and the delay
TFSCM elapsed.
TABLE 6-2: OSCILLATOR PARAMETERS
Symbol
Parameter
Value
VPOR
TPOR
VBOR
TBOR
TPWRT
TFSCM
POR threshold
POR extension time
BOR threshold
BOR extension time
Power-up time
delay
Fail-safe Clock
Monitor Delay
1.8V nominal
30 μs maximum
2.5V nominal
100 μs maximum
64 ms nominal
900 μs maximum
Note:
When the device exits the Reset condi-
tion (begins normal operation), the
device operating parameters (voltage,
frequency, temperature, etc.) must be
within their operating ranges, otherwise
the device may not function correctly. The
user application must ensure that the
delay between the time power is first
applied, and the time SYSRST becomes
inactive, is long enough to get all
operating
parameters
within
specification.
DS39997C-page 66
Preliminary
© 2011-2012 Microchip Technology Inc.