CAT811, CAT812
DETAILED DESCRIPTION
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.
Power 5V
Supply
Voltage 0V
Threshold
Voltage
Reset Timeout Period
140ms
minimum
5V
RESET
0V
5V
RESET
0V
CAT811
CAT812
Figure 1. Reset Timing Diagram
V
CC
TRANSIENT RESPONSE
The CAT811/812 protect µPs against brownout
failure. Short duration transients of 4µs or less and
100mV amplitude typically do not cause a false
RESET.
Figure 2 shows the maximum pulse duration of
negative-going V
CC
transients that do not cause a
reset condition.
30
As the amplitude of the transient goes further below
the threshold (increasing V
TH
- V
CC
), the maximum
pulse duration decreases. In this test, the V
CC
starts
from an initial voltage of 0.5V above the threshold and
drops below it by the amplitude of the overdrive
voltage (V
TH
- V
CC
).
TRANSIENT DURATION (s)
25
20
15
10
5
0
1
CAT8xxM
10
T
AMB
= 25°C
CAT8xxZ
100
1000
RESET OVERDRIVE V
TH
- V
CC
(mV)
Figure 2. Maximum Transient Duration without Causing a
Reset Pulse vs. Reset Comparator Overdrive
Doc. No. MD-3005 Rev. S
6
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
CATALYST [ CATALYST SEMICONDUCTOR ]
