a negative-going pulse applied to V
CC
, starting above
the actual reset threshold and ending below it by the
magnitude indicated (reset comparator overdrive). The
graph indicates the typical maximum pulse width a neg-
ative-going V
CC
transient may have without causing a
reset pulse to be issued. As the magnitude of the tran-
sient increases (goes farther below the reset threshold),
the maximum allowable pulse width decreases. A 0.1µF
capacitor mounted as close as possible to V
CC
provides
additional transient immunity.
Ensuring a Valid RESET
Output Down to V
CC
= 0V
The MAX6381–MAX6390 are guaranteed to operate
properly down to V
CC
= 1V. In applications that require
valid reset levels down to V
CC
= 0V, a pulldown resistor
to active-low outputs (push/pull only, Figure 2) and a
pullup resistor to active-high outputs (push/pull only)
will ensure that the reset line is valid while the reset out-
put can no longer sink or source current. This scheme
does not work with the open-drain outputs of the
MAX6383/MAX6386/MAX6389/MAX6390. The resistor
value used is not critical, but it must be small enough
not to load the reset output when V
CC
is above the
reset threshold. For most applications, 100kΩ is ade-
quate.
MAX6381–MAX6390
SC70/µDFN, Single/Dual Low-Voltage,
Low-Power µP Reset Circuits
7
