Texas Instruments TPS3801, Application Report

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Manual Reset
11 TPS3801/09 – Smallest SVS for Monitoring DSPs and Processors
4 Manual Reset
4.1 Functional Description
The manual reset is an input for triggering a reset by an external component. As
an example, a pushbutton switch or a microcontroller or a DSP port can provide
the manual reset. The reset will be asserted for the time of a low signal at manual
reset input plus delay time t
d
.
An internal pullup resistor of 30 k
Ω
between manual reset input and V
DD
makes
an external pullup resistor unnecessary. This input can be left floating, if it is not
used.
4.2 A Measurement of Low Pulse at the Manual Reset Input
For a better illustration, a measurement of a low pulse of 100 ms at manual reset
and the resulting reset pulse is shown in Figure 13. The measurement has been
made at a TPS3801I50.
MR and RESET MR and RESET
RESET
Figure 13. Reset Pulse, Triggered by Manual Reset
4.3 Minimum Conditions for Triggering a Manual Reset
As specified in the datasheet, a high-to-low transition from 0.7
×
V
DD
to 0.3
×
V
DD
with a duration of at least 100ns is enough to trigger a reset. For shorter signals
at manual reset input, the triggering of a reset can not be assured.