CAT811_08 Datasheet, PDF (6/11 Pages) Catalyst Semiconductor – 4-Pin Microprocessor Power Supply Supervisors with Manual Reset

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
5V
RESET
0V
5V
RESET
0V
Threshold
Voltage
Reset Timeout Period
140ms
minimum
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.
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).
30
25
T_AMB = 25°C
20
15
CAT8xxZ
10
5
CAT8xxM
0
1
10
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