Datasheet

MAX703/MAX704
Using the Power-Fail Comparator
to Assert Reset
In addition to asserting reset at the V
CC
reset threshold
voltage, reset can also be asserted at the PFI input
threshold voltage. Connect PFO to MR to initiate a reset
pulse when the monitored supply drops below a user-
specified threshold or when V
CC
falls below the reset
threshold. For additional noise rejection, place a
capacitor between PFI and GND.
Low-Cost Microprocessor Supervisory
Circuits with Battery Backup
8 _______________________________________________________________________________________
PART
NOMI NAL
RESET
THRESHOLD
( V)
M I NI M UM
RESET
PULSE
WI DTH
( m s)
NOMI NAL
WATCH-
DOG
TI MEOUT
PERI OD
( s )
BACKUP-
BATTERY
SWITCH
CE
WRITE
PROTECT
POWER- FAI L
COMPARATOR
M ANUAL
RESET
I NPUT
WATCH-
DOG
I NPUT
LOW-
LI NE
OUTPUT
ACTI VE-
HI GH
RESET
BATT
ON
OUTPUT
MAX690A 4.65 140 1.6 Yes No Yes No No No No No
MAX691A 4.65 140/Adj. 1.6/Adj. Yes Yes Yes No Yes Yes Yes Yes
MAX692A 4.40 140 1.6 Yes No Yes No No No No No
MAX693A 4.40 140/Adj. 1.6/Adj. Yes Yes Yes No Yes Yes Yes Yes
MAX696 Adj. 35/Adj. 1.6/Adj. Yes No Yes No Yes Yes Yes Yes
MAX697 Adj. 35/Adj. 1.6/Adj. No Yes Yes No Yes Yes Yes No
MAX700 4.65/Adj. 200 — No No No Yes No No Yes No
MAX703 4.65 140 — Yes No Yes Yes No No No No
MAX704 4.40 140 — Yes No Yes Yes No No No No
MAX705 4.65 140 1.6 No No Yes Yes Yes No No No
MAX706 4.40 140 1.6 No No Yes Yes Yes No No No
MAX707 4.65 140 — No No Yes Yes No No Yes No
MAX708 4.40 140 — No No Yes Yes No No Yes No
MAX791 4.65 140 1.0 Yes Yes Yes Yes Yes Yes Yes Yes
MAX1232 4.50/4.75 250
0.15/0.60/
1.2
No No No Yes No No Yes No
MAX1259 — — — Yes No Yes No No No No No
Table 3. Maxim Microprocessor Supervisory Products