Datasheet

MAX6316–MAX6322
5-Pin µP Supervisory Circuits with
Watchdog and Manual Reset
6
Maxim Integrated
_______________Detailed Description
A microprocessor’s (µP) reset input starts or restarts the
µP in a known state. The reset output of the MAX6316–
MAX6322 µP supervisory circuits interfaces with the
reset input of the µP, preventing code-execution errors
during power-up, power-down, and brownout condi-
tions (see the Typical Operating Circuit ). The MAX6316/
MAX6317/MAX6318/MAX6320/MAX6321 are also capa-
ble of asserting a reset should the µP become stuck in
an infinite loop.
Reset Output
The MAX6316L/MAX6318LH/MAX6319LH feature an
active-low reset output, while the MAX6317H/
MAX6318_H/MAX6319_H/MAX6321HP/MAX6322HP
feature an active-high reset output. RESET is guaran-
teed to be a logic low and RESET is guaranteed to be a
logic high for V
CC
down to 1V.
The MAX6316–MAX6322 assert reset when V
CC
is below
the reset threshold (V
RST
), when MR is pulled low
(MAX6316_/MAX6317H/MAX6319_H/MAX6320P/
MAX6322HP only), or if the WDI pin is not serviced within
the watchdog timeout period (t
WD
). Reset remains assert-
ed for the specified reset active timeout period (t
RP
) after
V
CC
rises above the reset threshold, after MR transitions
low to high, or after the watchdog timer asserts the reset
(MAX6316_/MAX6317H/MAX6318_H/MAX6320P/
MAX6321HP). After the reset active timeout period (t
RP
)
expires, the reset output deasserts, and the watchdog
timer restarts from zero (Figure 2).
MAX6316–MAX6322
V
CC
V
CC
WDI
(ALL EXCEPT
MAX6319/MAX6322)
1.23V
52kΩ
52kΩ
GND
RESET
(ALL EXCEPT
MAX6316/MAX6320P)
RESET
(ALL EXCEPT MAX6317)
MR
(ALL EXCEPT
MAX6318/MAX6321)
RESET
GENERATOR
WATCHDOG
TIMER
WATCHDOG
TRANSITION
DETECTOR
Figure 1. Functional Diagram
V
CC
1V
1V
t
RD
V
RST
V
RST
t
RD
RESET
GND
RESET
t
RP
t
RP
GND
Figure 2. Reset Timing Diagram