
ADM8696/ADM8697
REV. 0
–4–
PIN FUNCT ION DE SCRIPT ION
Pin No.
Mnemonic
ADM8696
ADM8697
Function
V
CC
V
BAT T
V
OUT
3
1
2
3
—
—
Power Supply Input +3 V to +5 V.
Backup Battery Input.
Output Voltage, V
CC
or V
BAT T
is internally switched to V
OUT
depending on which is at
the highest potential. When V
CC
is higher than V
BAT T
and L L
IN
is higher than the reset
threshold, V
CC
is switched to V
OUT
. When V
CC
is lower than V
BAT T
and LL
IN
is below the
reset threshold, V
BAT T
is switched to V
OUT
. V
OUT
can supply up to 100 mA to power CMOS
RAM. Connect V
OUT
to V
CC
if V
OUT
and V
BAT T
are not used.
0 V. Ground reference for all signals.
Logic Output.
RESET
goes low whenever LL
IN
falls below 1.3 V and remains low for 50 ms
after LL
IN
goes above 1.3 V.
RESET
also goes low for 50 ms if the watchdog timer is en-
abled but not serviced within its timeout period. T he
RESET
pulse width can be adjusted as
shown in T able I.
Watchdog Input, WDI is a three level input. If WDI remains either high or low for longer
than the watchdog timeout period,
RESET
pulses low and
WDO
goes low. T he timer resets
with each transition at the WDI input. T he watchdog timer is disabled when WDI is left
floating or is driven to midsupply.
Power Fail Input. PFI is the noninverting input to the Power Fail Comparator when PFI is
less than 1.3 V,
PFO
goes low. Connect PFI to GND or V
OUT
when not used. See Figure 1.
Power Fail Output.
PFO
is the output of the Power Fail Comparator. It goes low when PFI
is less than 1.3 V. T he comparator is turned off and
PFO
goes low when V
CC
is below
V
BAT T
.
Logic Input. T he input to the CE gating circuit. Connect to GND or V
OUT
if not used.
Logic Output.
CE
OUT
is a gated version of the
CE
IN
signal.
CE
OUT
tracks
CE
IN
when LL
IN
is above 1.3 V. If LL
IN
is below 1.3 V,
CE
OUT
is forced high.
Logic Output. BAT T ON goes high when V
OUT
is internally switched to the V
BAT T
input.
It goes low when V
OUT
is internally switched to V
CC
. T he output typically sinks 7 mA and
can directly drive the base of an external PNP transistor to increase the output current above
the 100 mA rating of V
OUT
.
Logic Output.
LOW LINE
goes low when LL
IN
falls below 1.3 V. It returns high as soon as
LL
IN
rises above 1.3 V.
Logic Output. RESET is an active high output. It is the inverse of
RESET
.
Logic Oscillator Select Input. When OSC SEL is unconnected or driven high, the internal
oscillator sets the reset time delay and watchdog timeout period. When OSC SEL is low, the
external oscillator input, OSC IN, is enabled. OSC SEL has a 3
μ
A internal pull-up. See
T able I and Figure 4.
Logic Oscillator Input. When OSC SEL is low, OSC IN can be driven by an external clock
to adjust both the reset delay and the watchdog timeout period. T he timing can also be
adjusted by connecting an external capacitor to this pin. See T able I and Figure 4. When
OSC SEL is high or floating, OSC IN selects between fast and slow watchdog timeout periods.
Logic Output. T he Watchdog Output,
WDO
, goes low if WDI remains either high or low
for longer than the watchdog timeout period.
WDO
is set high by the next transition at
WDI. If WDI is unconnected or at midsupply,
WDO
remains high.
WDO
also goes high
when
LOW LINE
goes low.
No Connect. It should be left open.
Voltage Sensing Input. T he voltage on the low line input, LL
IN
, is compared with a 1.3 V
reference voltage. T his input is normally used to monitor the power supply voltage. T he
output of the comparator generates a
LOW LINE
output signal. It also generates a
RESET /
RESET
output. T he comparator output also controls the battery switchover circuitry.
T his is a special test pin using during device manufacture. It should be connected to GND.
GND
RESET
4
15
5
15
WDI
11
11
PFI
9
9
PFO
10
10
CE
IN
CE
OUT
—
—
13
12
BAT T ON
5
—
LOW LINE
6
6
RESET
OSC SEL
16
8
16
8
OSC IN
7
7
WDO
14
14
NC
LL
IN
12
13
2
4
T EST
—
1