Datasheet

MAX801L/M/N, MAX808L/M/N
8-Pin µP Supervisory Circuits
with ±1.5% Reset Accuracy
_______________________________________________________________________________________ 7
_________________________________________________Pin Description (continued)
Active-High Reset Output. RESET is the inverse of RESET. It is a CMOS output that
sources and sinks current. RESET swings between V
CC
and GND.
—5
Chip-Enable Output. Output to the chip-enable gating circuit. CE OUT is pulled up to
the higher of V
CC
or V
BATT
when the chip-enable gate is disabled.
5—
Watchdog Input. If WDI remains high or low longer than the watchdog timeout period
(typically 1.6sec), RESET will be asserted for 200ms. Leave unconnected to disable the
watchdog function.
—6
Chip-Enable Input6—
RESET
CE OUT
WDI
CE IN
BATT
OUT
Backup-Battery Input. When V
CC
falls below the reset threshold and V
BATT
, OUT switch-
es from V
CC
to BATT. V
BATT
may exceed V
CC
. The battery can be removed while the
MAX801/MAX808 is powered up, provided BATT is bypassed with a 0.1µF capacitor to
GND. If no battery is used, connect BATT to ground and V
CC
to OUT.
77
Output Supply Voltage to CMOS RAM. When V
CC
exceeds the reset threshold or V
BATT
,
OUT connects to V
CC
. When V
CC
falls below the reset threshold and V
BATT
, OUT con-
nects to BATT. Bypass OUT with a 0.1µF capacitor to GND.
88
NAME
MAX801 MAX808
FUNCTION
PIN
MAX801
MAX808
CE IN
GND
V
CC
BATT
THE HIGHER
OF V
CC
OR V
BATT
MAX801 ONLY
MAX808 ONLY
BATTERY-BACKUP
COMPARATOR
RESET
COMPARATOR
LOW-LINE
COMPARATOR
2.275V
OUT
LOWLINE
WDI
RESET (MAX801 ONLY)
RESET
CE OUT
P
P
N
WATCHDOG
TRANSITION
DETECTOR
STATE
MACHINE
OSCILLATOR
Figure 1. Functional Diagram