PIC24HJ12GP201_11 Datasheet, PDF (55/262 Pages) Microchip Technology – High-Performance, 16-bit Microcontrollers 5-cycle latency

PIC24HJ12GP201/202
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 programmable 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 oper-
ation. 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
1.8V nominal
POR extension time 30 μs maximum
BOR threshold
2.5V nominal
BOR extension time 100 μs maximum
Programmable
power-up time
delay
0-128 ms nominal
Fail-safe Clock
Monitor Delay
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, other-
wise the device may not function cor-
rectly. 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.
© 2007-2011 Microchip Technology Inc.
DS70282E-page 55