Datasheet
12
LTC2900
2900f
TYPICAL APPLICATIO S
U
Quad Supply Monitor with Push-Button Reset
5V, 3V, 1.8V, 12V (ADJ)
V3
V1
CRT
RST
PBR
V2
V4
V
REF
V
PG
GND
5
NORMALLY
OPEN
C
RT
3V
12V
SYSTEM
RESET
R4
100k
1%
R3
2.15M
1%
4
6
7
8
9
10
3
2
1
1.8V
5V
V
TRIP
= 11.25V
LTC2900
2900 TA02
5V, –5V Monitor and Unused V2, V3 Inputs
Pulled Above Trip Thresholds
V3
V1
CRT
RST
PBR
V2
V4
V
REF
V
PG
GND
5
C
RT
SYSTEM
RESET
–5V
R3
464k
1%
R4
121k
1%
R2
86.6k
1%
R1
16.2k
1%
4
6
7
8
9
10
3
2
1
5V
LTC2900
2900 TA03
V
TRIP
= –4.64V
Ensuring Reset Valid for V
CC
Down to 0V (LTC2900-2)
Some applications require the reset output (RST) to be
valid with V
CC
down to 0V. The LTC2900-2 is designed to
handle this requirement with the addition of an external
resistor from RST to ground. The resistor will provide a
path for stray charge and/or leakage currents, preventing
the RST output from floating to undetermined voltages
when connected to high impedance (such as CMOS logic
inputs). The resistor value should be small enough to
provide effective pull-down without excessively loading
the active pull-up circuitry. Too large a value may not pull
down well enough. A 100k resistor from RST to ground is
satisfactory for most applications.
APPLICATIO S I FOR ATIO
WUUU