Datasheet

Reset Output
A µP’s reset input starts the µP in a known state.
Whenever the µP is in an unknown state, it should be
held in reset. The MAX814/MAX815/MAX816 assert reset
during power-up, power-down, or brownout conditions.
On power-up, once V
CC
reaches 1V, RESET is a guar-
anteed logic low of 0.4V or less. As V
CC
rises, RESET
stays low. As V
CC
rises above the reset threshold, an
internal timer releases RESET after 200ms. RESET also
pulses low whenever V
CC
dips below the reset thresh-
old (i.e., brownout condition). If brownout occurs in the
middle of a previously initiated reset, the internal timer
is reset and the output remains low for at least another
140ms after the brownout ends. On power-down, once
V
CC
falls below the reset threshold, RESET stays low
and is guaranteed to be less than 0.3V until V
CC
drops
below 1V.
The MAX814 and MAX816 also offer active-high RESET
outputs. They are the inverse of the RESET outputs.
MAX814/MAX815/MAX816
±1% Accuracy, Low-Power, +3V and +5V
µP Supervisory Circuits
_______________________________________________________________________________________ 9
MAX814
RESET
GENERATOR
RESET THRESHOLD
POWER- FAIL THRESHOLD
60mV
1
150µA
8
7
6
5
MR
RESET
RESET
LOW LINE
PFO
V
CC
PFI
2
4
GND
3
MAX815
TIMEBASE
RESET THRESHOLD
POWER-FAIL THRESHOLD
150µA
6
8
7
5
MR
V
CC
WDO
RESET
PFO
WDI
PFI
2
1
4
GND
3
RESET
GENERATOR
WATCHDOG
TIMER
WATCHDOG
TRANSITION
DETECTOR
MAX816
RESET
GENERATOR
1.70V
1.70V
1
2
150µA
8
7
5
MR
V
CC
RESET
RESET
PFO
RESET IN
PFI
6
4
GND
3
Figure 4. MAX814 Block Diagram Figure 5. MAX815 Block Diagram
Figure 6. MAX816 Block Diagram