TC1278/TC1279
3.0 APPLICATIONS INFORMATION
3.1 Operation – Power Monitor
The TC1278/TC1279 provide the function of detecting
out-of-tolerance power supply conditions and warning
a processor-based system of impending power failure.
When VCC is detected as out-of-tolerance, the RESET
signal is asserted. On power-up, RESET is kept active
for approximately 350msec after the power supply has
reached the selected tolerance. This allows the power
supply and microprocessor to stabilize before RESET
is released.
FIGURE 3-1:
Timing Diagram –
Power Up (TC1279)
4.00V
tR
4.75V
VCCTP
VCC
RESET
tRPU1
VOH
FIGURE 3-2:
Timing Diagram –
Power Down (TC1279)
tF
VCC
4.75V
VCCTP
4.00V
FIGURE 3-3:
Timing Diagram –
Power Up (TC1278)
tR
VCCTP(MIN)
VCCTP(MAX)
VCCTP
VCC
tRPU2
RESET
VOL
FIGURE 3-4:
VCC
4.74V
VCCTP
Timing Diagram –
Power Down (TC1278)
tF
4.00V
tRPD2
RESET
VOH
RESET SLEWS WITH VCC
RESET
tRPD1
VOL
DS21384B-page 4
© 2002 Microchip Technology Inc.