MC33465 Datasheet, PDF (6/8 Pages) ON Semiconductor – Micropower Undervoltage Sensing Circuits with Programmable Ouput Delay

MC33465
Figure 12. Typical Open Drain Application
VDD
2 Input
5
MC33465
1
CD
CD
Series
Reset
3 Gnd
R
VDD
Reset
CPU
Gnd
Figure 13. Typical Complementary Output Application
VDD
2 Input
5
MC33465
1
CD
CD
Series
Reset
3 Gnd
VDD
Reset
CPU
Gnd
APPLICATION CIRCUIT INFORMATION
The MC33465 series are micropower undervoltage
sensing circuits which offer a programmable time delayed
output with the choice of either complementary output drive
or open drain output configurations. Figure 14 shows the
timing relationships between the input voltage and the
resulting circuit waveforms. When the input voltage (Vin)
exceeds the sense comparator threshold, the timing
capacitor is allowed to charge through the internal delay
resistor. When the output inverting driver threshold is
exceeded, the Reset output switches from a logic “0” to a
logic “1”. The top curve of Figure 11 provides the nominal
delay time for a given value of delay capacitance. When Vin
drops below the comparator threshold minus hysteresis
voltage, the delay capacitor discharges. When the
capacitance voltage drops below the inverting drive
threshold, the output switches from a logic “1” to a logic “0”.
The bottom curve in Figure 11 provides typical delay time for
given delay capacitance values. The inverting driver
threshold voltage is typically about Vin/2, as shown in
Figure 10.
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