SC70, Single/Dual Low-Voltage,
Low-Power µP Reset Circuits
MAX6381–MAX6390
V
CC
V
IN
R1
RESET IN
R2
GND
( ) IS FOR MAX6388
MAX6387
MAX6388
MAX6389
RESET
(RESET)
GND
MAX6381
MAX6384
MAX6387
RESET
R1
100k
V
CC
Figure 1. RESET IN Configuration
Figure 2. RESET Valid to V
CC
= Ground Circuit
Reset Timeout Delay
SUFFIX
D1
D2
D3
D5
D6
D4
D7
MAX6390XSD4
MAX6390XSD7
MIN
1ms
20ms
140ms
280ms
560ms
1120ms
1200ms
1120/140ms *
1200/150ms *
PART
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 adequate.
Standard Versions
RESET
THRESHOLD
46
44
31
29
MAX638_
26
23
22
17
16
46
44
31
29
MAX6390
26
23
22
17
16
D4
D3
RESET TIMEOUT
* The MAX6390 has a 1120ms or 1200ms
RESET
timeout and a
140ms or 150ms manual reset timeout
a negative-going pulse applied to V
CC
, starting above the
actual reset threshold and ending below it by the magni-
tude indicated (reset comparator overdrive). The graph
indicates the typical maximum pulse width a negative-
going V
CC
transient may have without causing a reset
pulse to be issued. As the magnitude of the transient
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
= 0
The MAX6381–MAX6390 are guaranteed to operate
properly down to V
CC
= 1V. In applications that require
valid reset levels down to V
CC
= 0, 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 output
can no longer sink or source current. This scheme does
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