MAX6316_11 Datasheet, PDF (6/14 Pages) Maxim Integrated Products – 5-Pin uP Supervisory Circuits with Watchdog and Manual Reset

5-Pin µP Supervisory Circuits with
Watchdog and Manual Reset
V_CC
MR
(ALL EXCEPT
MAX6318/MAX6321)
WDI
(ALL EXCEPT
MAX6319/MAX6322)
V_CC
52kΩ
1.23V
WATCHDOG
TRANSITION
DETECTOR
52kΩ
MAX6316–MAX6322
RESET
GENERATOR
RESET
(ALL EXCEPT MAX6317)
RESET
(ALL EXCEPT
MAX6316/MAX6320P)
WATCHDOG
TIMER
GND
Figure 1. Functional Diagram
_______________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).
V_CC
1V
GND
RESET
V_RST
t_RP
V_RST
1V
t_RD
RESET
t_RP
t_RD
GND
Figure 2. Reset Timing Diagram
6 _______________________________________________________________________________________