7

CAT811, CAT812

Patent Pending

Doc. No. 3005, Rev. P

DETAILED DESCRIPTIONS

RESET TIMING

The reset signal is asserted LOW for the CAT811 and HIGH for the CAT812 when the power supply voltage falls below

the threshold trip voltage and remains asserted for at least 140ms after the power supply voltage has risen above the

threshold.

The CAT811/812 protect

µPs against brownout failure. Short duration transients of 4µsec or less and 100 mV

amplitude typically do not cause a false RESET.

Figure 1. Reset Timing Diagram

Figure 2. Maximum Transient Duration Without Causing a Reset Pulse vs. Reset Comparator Overdrive

30

25

20

15

10

5

0

RESET OVERDRIVE VTH - VCC [mV]

1

10

100

1000

TAMB = 25°C

CAT8xxM

CAT8xxZ

5V

0V

5V

0V

5V

0V

CAT811

CAT812

Threshold

Voltage

140ms

minimum

Reset Timeout Period

Power

Supply

Voltage

RESET

RESET