CAT853 Datasheet, PDF (4/9 Pages) Catalyst Semiconductor – 3-Pin Microprocessor Power Supply Supervisors

CAT853, CAT863, CAT859, CAT869
DETAILED DESCRIPTIONS
RESET TIMING
The reset signal is asserted low for the CAT853, CAT863,
CAT859, and CAT869 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
5V
RESET
0V
140ms
minimum
Figure 1. Reset Timing Diagram
V_CC TRANSIENT RESPONSE
The CAT853, CAT863, CAT859, and CAT869 protect
μPs against brownout failure. Short duration transients
of 4μsec 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).
Figure 2. Maximum Transient Duration Without Causing a Reset Pulse vs. Reset Comparator Overdrive
Doc. No. 3026, Rev. B
4
© 2007 by Catalyst Semiconductor, Inc.
Characteristics subject to change without notice