CAT809 datasheet(7/13 Pages) CATALYST

7 / 13 page

CAT809, CAT810

Patent Pending

Doc. No. 3004, Rev. S

DETAILED DESCRIPTIONS

RESET TIMING

The reset signal is asserted LOW for the CAT809 and HIGH for the CAT810 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.

VCC TRANSIENT RESPONSE

The CAT809/810 protect

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

amplitude typically do not cause a false RESET.

Figure 2 shows the maximum pulse duration of negative-going VCC transients that do not cause a reset condition. As

the amplitude of the transient goes further below the threshold (increasing VTH - VCC), the maximum pulse duration

decreases. In this test, the VCC starts from an initial voltage of 0.5V above the threshold and drops below it by the

amplitude of the overdrive voltage (VTH - VCC).

CAT809

CAT810

Threshold

Voltage

140ms

minimum

Reset Timeout Period

Power

Supply

Voltage

RESET

FIGURE 1. RESET TIMING DIAGRAM

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

RESET OVERDRIVE VTH - VCC [mV]

100

1000

TAMB = 25°C

CAT809M

CAT809Z

CAT809 Datasheet(PDF) 7 Page - Catalyst Semiconductor