MC33464 Datasheet, PDF (5/8 Pages) ON Semiconductor – MICROPOWER UNDERVOLTAGE SENSING CIRCUITS

MC33464
Figure 7. Microprocessor Reset Circuit with Delay
2 Input
Vin
Vref
1
Reset
470 k
CDelay
3 Gnd
Microprocessor
A time delayed reset can be accomplished with the addition of CDelay. Figure 5 provides a graph of time delays, for both rising
and falling output waveform edges, as a function of CDelay. If another value of pullup resistance is used, the time delay can be
calculated by using the equation:
ȧȧȧȱȲ_{ǒ Ǔ}^{ȳȴȧȧȧ} _{+ tDelay R CDelay}
1
1
–
Vth(MPU)
Vin
) t_p
where VthMPU is the microprocessor reset input threshold voltage and tp is the propagation delay internal to the MC33464.
Figure 8. Microprocessor Reset Circuit
2 Input
Vin
Vref
1
Reset
3 Gnd
Microprocessor
MOTOROLA ANALOG IC DEVICE DATA
5