Datasheet

Table 1. MAX696 and MAX697 Reset Pulse Width and Watchdog Timeout Selections
(Notes 1, 2)
Table 2. Input and Output Status in Battery-Backup Mode
OSC SEL
(Note 3)
OSC IN
WATCHDOG TIMEOUT PERIOD
RESET TIMEOUT
PERIOD
NORMAL
IMMEDIATELY
AFTER RESET
Low External Clock Input 1024 clocks 4096 clocks 512 clocks
Low External Capacitor 400ms/47pF x C 1.6s/47pF x C 200ms/47pF x C
High/Floating Low 100ms 1.6s 50ms
High/Floating Floating 1.6s 1.6s 50ms
I/O STATUS
V
BATT
, V
OUT
V
BATT
is connected to V
OUT
with an internal MOSFET (MAX696 only).
RESET
Logic-low.
RESET Logic-high. The open-circuit output voltage is equal to V
OUT
.
LOW LINE
Logic-low.
BATT ON Logic-high (MAX696 only).
WDI
WDI is internally disconnected from its internal pullup and does not source or sink current as long as its input
voltage is between GND and V
OUT
. The input voltage does not affect supply current.
WDO
Logic-high.
PFI The power-fail comparator is turned off and the power-fail input voltage has no effect on the power-fail output.
PFO
Logic-low.
CE IN
CE IN is internally disconnected from its internal pullup and does not source or sink current as long as its input
voltage is between GND and V
OUT
. The input voltage does not affect supply current (MAX696 only).
CE OUT
Logic-high (MAX697 only).
OSC IN OSC IN is ignored.
OSC SEL OSC SEL is ignored.
V
CC
Approximately 12µA is drawn from the V
BATT
input when V
CC
is between (V
BATT
+ 100mV) and (V
BATT
-
700mV). The supply current is 1µA maximum when V
CC
is less than V
BATT
- 700mV.
Note 1: When the MAX696/MAX697 OSC SEL pin is low, OSC IN can be driven by an external clock signal, or an external
capacitor can be connected between OSC IN and GND. The nominal internal oscillator frequency is 10.24kHz. The
nominal oscillator frequency with external capacitor is f
OSC
(Hz) = 184,000/C
OSC
(pF).
Note 2: See the Electrical Characteristics table for minimum and maximum timing values.
Note 3: High for the OSC SEL pin should be connected to V
OUT
, not V
CC
(on the MAX696).
MAX696/MAX697 Microprocessor Supervisory Circuits
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