LTC690 Linear Technology, LTC690 Datasheet - Page 5

• Manufacturer Part Number: LTC690
• Description: Microprocessor Supervisory Circuits
• Manufacturer: Linear Technology

PI FU CTIO S
V
with a 0.1 F capacitor.
V
a capacitor of 0.1 F or greater. During normal operation,
V
switch, M1, which can deliver up to 50mA and has a typical
on resistance of 5 . When V
is internally switched to V
used, connect V
V
auxiliary power, connected to V
through PMOS switch, M2. If back-up battery or auxiliary
power is not used, V
BLOCK
CC
OUT
OUT
BATT
U
: 5V Supply Input. The V
: Voltage Output for Backed Up Memory. Bypass with
obtains power from V
: Back-Up Battery Input. When V
U
I D AGRA
OUT
to V
OSC SEL
BATT
U
OSC IN
V BATT
CE IN
V CC
WDI
PFI
CC
should be connected to GND.
BATT
W
.
CC
CC
CC
. If V
through an NMOS power
BATT
is lower than V
pin should be bypassed
OUT
, is delivered to V
CC
TRANSITION
DETECTOR
1.3V
GND
OSC
and V
falls below V
–
+
–
+
BATT
–
+
C1
C2
C3
BATT
are not
, V
BATT
OUT
OUT
M2
,
RESET PULSE
GENERATOR
WATCHDOG
TIMER
GND: Ground pin.
BATT ON: Battery On Logic Output from Comparator C2.
BATT ON goes low when V
V
drive for an external PNP transistor to increase the output
current above the 50mA rating of V
high when V
PFI: Power Failure Input. PFI is the noninverting input to
the power-fail comparator, C3. The inverting input is
internally connected to a 1.3V reference. The power failure
output remains high when PFI is above 1.3V and goes low
when PFI is below 1.3V. Connect PFI to GND or V
C3 is not used.
CC
CHARGE
PUMP
. The output typically sinks 35mA and can provide base
M1
OUT
is internally switched to V
OUT
LTC694/LTC695
LTC690/LTC691
BATT ON
CE OUT
LOW LINE
PFO
RESET
RESET
WDO
690 BD
is internally connected to
V OUT
OUT
. BATT ON goes
BATT
.
OUT
when
5