Datasheet

Typical Applications
MAX696
A typical connection for the MAX696 is shown in
Figure 1. CMOS RAM is powered from V
OUT
. V
OUT
is internally connected to V
CC
when power is present,
or to V
BATT
when V
CC
is less than the battery voltage.
V
OUT
can supply 50mA from V
CC
, but if more current is
required, an external pnp transistor can be added. When
V
CC
is higher than V
BATT
, the BATT ON output goes
low, providing 7mA of base drive for the external transis-
tor. When V
CC
is lower than V
BATT
, an internal 200Ω
MOSFET connects the backup battery to V
OUT
. The qui-
escent current in the battery-backup mode is 1μA maxi-
mum when V
CC
is between 0V and (V
BATT
- 700mV).
Reset Output
A voltage detector monitors V
CC
and generates a RESET
output to hold the microprocessor’s RESET line low when
LL
IN
is below 1.3V. An internal monostable holds RESET
Figure 1. MAX696 Typical Application
PIN
NAME FUNCTION
MAX696 MAX697
— 1 TEST Used During Maxim Manufacture Only. Always ground this pin.
— 12 CE OUT CE OUT goes low only when CE IN is low and LL
IN
is above 1.3V. See Figure 5.
— 13 CE IN The Input to the CE Gating Circuit. Connect to GND or V
OUT
if not used.
0.1µF
0.1µF
3 5
2
V
OUT
V
V
BATT
CC
RESETRESET
LOW LINE
RESET
LL
IN
PFO
WDO
BATT ON
CMOS
RAM
A0–A15
MICROPROCESSOR
11
10
15
18
I/O
NMI
WDI
OTHER SYSTEM RESET SOURCES
SYSTEM STATUS INDICATORS
AUDIBLE
ALARM
146
+5V
V
CC
INPUT
1
9
4
7
8
13
PFI
GND
OSC IN
OSC SEL
NO CONNECTION
RESET
3V
BATTERY
MAX696
MAX696/MAX697 Microprocessor Supervisory Circuits
www.maximintegrated.com
Maxim Integrated │ 6
Pin Description (continued)