LTC2902
Programmable Quad Supply
Monitor with Adjustable Reset Timer
and Supply Tolerance
DESCRIPTIO
The LTC
®
2902 is a programmable supply monitor for sys-
tems with up to four supply voltages. One of 16 preset or
adjustable voltage monitor combinations can be selected
using an external resistor divider connected to the pro-
gram pin. The preset voltage thresholds are digitally pro-
grammable to 5%, 7.5%, 10% or 12.5% below the nomi-
nal operating voltage, and are accurate to 1.5% over tem-
perature. All four voltage comparator outputs are con-
nected to separate pins for individual supply monitoring.
The reset delay time is adjustable using an external
capacitor. Tight voltage threshold accuracy and glitch
immunity ensure reliable reset operation without false
triggering. The RST output is guaranteed to be in the
correct state for V
CC
down to 1V and may be disabled
during supply margin testing. The LTC2902-1 features
an open-drain RST output, while the LTC2902-2 has a
push-pull RST output.
The 43µA supply current makes the LTC2902 ideal for power
conscious systems and the part may be configured to
monitor less than four inputs. The LTC2902-1/LTC2902-2
are available in the 16-lead narrow SSOP package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
FEATURES
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Simultaneously Monitors Four Supplies
16 User Selectable Combinations of 5V, 3.3V, 3V,
2.5V, 1.8V, 1.5V and/or
±Adjustable
Voltage
Thresholds
Guaranteed Threshold Accuracy:
±1.5%
of Monitored
Voltage Over Temperature
Selectable Supply Tolerance: 5%, 7.5%,
10%, 12.5% Below Monitored Voltage
Low Supply Current: 43µA Typ
Adjustable Reset Time
RESET Disable Pin for Margining Applications
Open-Drain RST Output (LTC2902-1)
Push-Pull RST Output (LTC2902-2)
Individual Nondelayed Monitor Outputs for Each Supply
Power Supply Glitch Immunity
Guaranteed RESET for V
CC
≥
1V
APPLICATIO S
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Desktop and Notebook Computers
Multivoltage Systems
Telecom Equipment
Portable Battery-Powered Equipment
Network Servers
TYPICAL APPLICATIO
Quad Supply Monitor with Adjustable Tolerance (5V, 3.3V, 2.5V, 1.8V)
5V
3.3V
DC/DC
CONVERTER
2.5V
1.8V
R3
POWER
10k
V4
GOOD
2
V1
COMP1
16
COMP2
1
V2
COMP3
15
LTC2902-2 COMP4
6
V
REF
RST
8
RDIS
MARGIN
7
T0
TOLERANCE = 5%
9
V
PG
T1
GND
CRT
t
RST
= 216ms
10
5
C
RT
47nF
2902 TA01
V3
3
13
SYSTEM
LOGIC
4
14
C1
0.1µF
C2
0.1µF
R1
59k
1%
R2
40.2k
1%
12
11
U
U
U
2902f
1
LINEAR [ LINEAR INTEGRATED SYSTEMS ]
