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LTC2902
Programmable Quad Supply
Monitor with Adjustable Reset Timer
and Supply Tolerance
FEATURES
DESCRIPTIO
s Simultaneously Monitors Four Supplies
s 16 User Selectable Combinations of 5V, 3.3V, 3V,
2.5V, 1.8V, 1.5V and/or ±Adjustable Voltage
Thresholds
s Guaranteed Threshold Accuracy: ±1.5% of Monitored
Voltage Over Temperature
s Selectable Supply Tolerance: 5%, 7.5%,
10%, 12.5% Below Monitored Voltage
s Low Supply Current: 43µA Typ
s Adjustable Reset Time
s RESET Disable Pin for Margining Applications
s Open-Drain RST Output (LTC2902-1)
s Push-Pull RST Output (LTC2902-2)
s Individual Nondelayed Monitor Outputs for Each Supply
s Power Supply Glitch Immunity
Us Guaranteed RESET for VCC 1V
APPLICATIO S
s Desktop and Notebook Computers
s Multivoltage Systems
s Telecom Equipment
s Portable Battery-Powered Equipment
s Network Servers
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 VCC 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.
TYPICAL APPLICATIO
Quad Supply Monitor with Adjustable Tolerance (5V, 3.3V, 2.5V, 1.8V)
DC/DC
CONVERTER
5V
3.3V
2.5V
1.8V
C1
0.1µF
C2
0.1µF
R1
59k
1%
R2
40.2k
1%
SYSTEM
LOGIC
4
V1
3 13
V3 V4
2
R3
10k
POWER
GOOD
COMP1
16
COMP2
14
V2
1
COMP3
15
LTC2902-2 COMP4
12
VREF
6
RST
8
RDIS
MARGIN
11
VPG
GND
10
7
T0
9
T1
CRT
5 CRT
47nF
TOLERANCE = 5%
tRST = 216ms
2902 TA01
2902f
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LTC2902
ABSOLUTE AXI U RATI GS
(Notes 1, 2, 3)
V1, V2, V3, V4, VPG ..................................... – 0.3V to 7V
RST (LTC2902-1)........................................ – 0.3V to 7V
RST (LTC2902-2).......................... – 0.3V to (V2 + 0.3V)
COMPX, RDIS ............................................. – 0.3V to 7V
T0, T1 .......................................... – 0.3V to (VCC + 0.3V)
CRT ............................................. – 0.3V to (VCC + 0.3V)
VREF ............................................. – 0.3V to (VCC + 0.3V)
Reference Load Current (IVREF) ............................ ±1mA
V4 Input Current (– ADJ Mode) ............................ –1mA
Operating Temperature Range
LTC2902-1C/LTC2902-2C ....................... 0°C to 70°C
LTC2902-1I/LTC2902-2I .................... –40°C to 85°C
Storage Temperature Range .................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
UW U
PACKAGE/ORDER I FOR ATIO
TOP VIEW
COMP3 1
COMP1 2
V3 3
V1 4
CRT 5
RST 6
T0 7
RDIS 8
16 COMP2
15 COMP4
14 V2
13 V4
12 VREF
11 VPG
10 GND
9 T1
GN PACKAGE
16-LEAD PLASTIC SSOP
TJMAX = 125°C, θJA = 130°C/W
ORDER PART
NUMBER
LTC2902-1CGN
LTC2902-2CGN
LTC2902-1IGN
LTC2902-2IGN
GN16 PART MARKING
29021
29022
29021I
29022I
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS The q denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, unless otherwise noted. (Note 3)
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX UNITS
VRT50
5V, 5% Reset Threshold
5V, 7.5% Reset Threshold
5V, 10% Reset Threshold
5V, 12.5% Reset Threshold
V1 Input Threshold
q 4.600 4.675 4.750
q 4.475 4.550 4.625
q 4.350 4.425 4.500
q 4.225 4.300 4.375
V
V
V
V
VRT33
3.3V, 5% Reset Threshold
3.3V, 7.5% Reset Threshold
3.3V, 10% Reset Threshold
3.3V, 12.5% Reset Threshold
V1, V2 Input Threshold
q 3.036 3.086 3.135
q 2.954 3.003 3.053
q 2.871 2.921 2.970
q 2.789 2.838 2.888
V
V
V
V
VRT30
3V, 5% Reset Threshold
3V, 7.5% Reset Threshold
3V, 10% Reset Threshold
3V, 12.5% Reset Threshold
V2 Input Threshold
q 2.760 2.805 2.850
q 2.685 2.730 2.775
q 2.610 2.655 2.700
q 2.535 2.580 2.625
V
V
V
V
VRT25
2.5V, 5% Reset Threshold
2.5V, 7.5% Reset Threshold
2.5V, 10% Reset Threshold
2.5V, 12.5% Reset Threshold
V2, V3 Input Threshold
q 2.300 2.338 2.375
q 2.238 2.275 2.313
q 2.175 2.213 2.250
q 2.113 2.150 2.188
V
V
V
V
VRT18
1.8V, 5% Reset Threshold
1.8V, 7.5% Reset Threshold
1.8V, 10% Reset Threshold
1.8V, 12.5% Reset Threshold
V3, V4 Input Threshold
q 1.656 1.683 1.710
q 1.611 1.638 1.665
q 1.566 1.593 1.620
q 1.521 1.548 1.575
V
V
V
V
VRT15
1.5V, 5% Reset Threshold
1.5V, 7.5% Reset Threshold
1.5V, 10% Reset Threshold
1.5V, 12.5% Reset Threshold
V3, V4 Input Threshold
q 1.380 1.403 1.425
q 1.343 1.365 1.388
q 1.305 1.328 1.350
q 1.268 1.290 1.313
V
V
V
V
VRTA ADJ, 5% Reset Threshold
ADJ, 7.5% Reset Threshold
ADJ, 10% Reset Threshold
ADJ, 12.5% Reset Threshold
V3, V4 Input Threshold
q 0.492 0.500 0.508
q 0.479 0.487 0.494
q 0.466 0.473 0.481
q 0.453 0.460 0.467
V
V
V
V
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LTC2902
ELECTRICAL CHARACTERISTICS The q denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, unless otherwise noted. (Note 3)
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX UNITS
VRTAN
VCC
VCCMINP
VCCMINC
VREF
– ADJ Reset Threshold
Minimum Internal Operating Voltage
Minimum Required for Programming
Minimum Required for Comparators
Reference Voltage
V4 Input Threshold
RST, COMPX in Correct Logic State;
VCC Rising Prior to Program
VCC Rising
VCC Falling
VCC 2.3V, IVREF = ±1mA, CREF 1000pF
T0 Low, T1 Low
T0 Low, T1 High
T0 High, T1 Low
T0 High, T1 High
q
q
q
q
q
q
q
q
– 18 0
18
1
2.42
2.32
1.192
1.160
1.128
1.096
1.210
1.178
1.146
1.113
1.228
1.195
1.163
1.130
mV
V
V
V
V
V
V
V
VPG Programming Voltage Range
IVPG VPG Input Current
IV1 V1 Input Current
IV2 V2 Input Current
IV3 V3 Input Current
VCC VCCMINP
VPG = VREF
V1 = 5V, IVREF = 12µA, (Note 4)
V2 = 3.3V
V3 = 2.5V
V3 = 0.55V (ADJ Mode)
q0
q
VREF
±20
q 43 75
q 0.8 2
q 0.52 1.2
–15 15
V
nA
µA
µA
µA
nA
IV4 V4 Input Current
V4 = 1.8V
V4 = 0.55V (ADJ Mode)
V4 = –0.05V (–ADJ Mode)
q 0.34 0.8
q –15
15
q –15
15
µA
nA
nA
ICRT(UP)
ICRT(DN)
tRST
tUV
CRT Pull-Up Current
CRT Pull-Down Current
Reset Time-Out Period
VX Undervoltage Detect to RST or COMPX
VCRT = 0V
VCRT = 1.3V
CRT = 1500pF
VX Less Than Reset Threshold VRTX
by More Than 1%
q –1.4 –2 –2.6
q 10 20 30
q5 7 9
150
µA
µA
ms
µs
VOL Output Voltage Low RST, COMPX
ISINK = 2.5mA; V1 = 3V, V2 = 3V;
V3, V4 = 0V; VPG = 0V
q
0.15 0.4
ISINK = 100µA; V2 = 1V; V1, V3, V4 = 0V
ISINK = 100µA; V1 = 1V; V2, V3, V4 = 0V
q
q
0.05 0.3
0.05 0.3
VOH Output Voltage High RST, COMPX (Note 5) ISOURCE = 1µA
q V2 – 1
VOH
Output Voltage High RST (LTC2902-2)
ISOURCE = 200µA
(Note 6)
q 0.8 • V2
V
V
V
V
V
Digital Inputs T0, T1, RDIS
VIL
VIH
IINTOL
VIL
VIH
IRDIS
T0, T1 Low Level Input Voltage
T0, T1 High Level Input Voltage
T0, T1 Input Current
RDIS Input Threshold Low
RDIS Input Threshold High
RDIS Pull-Up Current
VCC = 3.3V to 5.5V
VCC = 3.3V to 5.5V
T0 = 0V, T1 = VCC
VCC = 3.3V to 5.5V
VCC = 3.3V to 5.5V
VRDIS = 0V
q 0.3VCC
q 0.7VCC
q ±0.1 ±1
q 0.4
q 1.6
– 10
V
V
µA
V
V
µA
Note 1: Absolute Maximum Ratings are those values beyond which the life of
a device may be impaired.
Note 2: All voltage values are with respect to GND.
Note 3: The greater of V1, V2 is the internal supply voltage (VCC).
Note 4: Under static no-fault conditions, V1 will necessarily supply quiescent
current. If at any time V2 is larger than V1, V2 must be capable of supplying
the quiescent current, programming (transient) current and reference load
current.
Note 5: The output pins RST and COMPX have internal pull-ups to V2 of
typically 6µA. However, external pull-up resistors may be used when faster
rise times are required or for VOH voltages greater than V2.
Note 6: The push-pull RST output pin on the LTC2902-2 is actively pulled up
to V2.
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LTC2902
TEST CIRCUITS
RST
LTC2902-1 OR COMPX
V1
V2
V3
ISOURCE
1µA
V4
2902 F01
Figure 1. RST, COMPX VOH Test
LTC2902-1
V1
V2 RST
V3 OR COMPX
V4
2902 F02
ISINK
2.5mA,
100µA
Figure 2. RST, COMPX VOL Test
LTC2902-2 RST
V1
V2
V3
ISOURCE
200µA
V4
2902 F03
Figure 3. Active Pull-Up RST VOH Test
WU W
TI I G DIAGRA
VX Monitor Timing
VX VRTX
RST
tUV
tRST
COMPX
1.5V
2902 TD
TYPICAL PERFOR A CE CHARACTERISTICS
5V Threshold Voltage
vs Temperature
4.75
4.70 5%
4.65
4.60
7.5%
4.55
4.50
4.45 10%
4.40
4.35
12.5%
4.30
4.25
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80 100
2902 G01
4
3.3V Threshold Voltage
vs Temperature
3.135
3.100
5%
3.065
3.030
2.995
7.5%
2.960
2.925
10%
2.890
2.855
12.5%
2.820
2.785
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80 100
2902 G02
3V Threshold Voltage
vs Temperature
2.850
2.815
5%
2.780
2.745
7.5%
2.710
2.675
2.640
10%
2.605
2.570
12.5%
2.535
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80 100
2902 G03
2902f

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TYPICAL PERFOR A CE CHARACTERISTICS
LTC2902
2.5V Threshold Voltage
vs Temperature
2.375
2.350
5%
2.325
2.300
2.275
7.5%
2.250
2.225
10%
2.200
2.175
2.150
12.5%
2.125
2.100
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80 100
2902 G04
ADJ Threshold Voltage
vs Temperature
0.508
0.503
5%
0.498
0.493
0.488
7.5%
0.483
0.478
0.473
10%
0.468
0.463
12.5%
0.458
0.453
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80 100
2902 G07
IV1 vs Temperature
100
V1 = 5V
90 V2 = 3.3V
80
V3 = 2.5V
V4 = 1.8V
70
60
50
40
30
20
10
0
– 60 –40 – 20 0 20 40 60 80 100
TEMPERATURE (°C)
2902 G10
1.8V Threshold Voltage
vs Temperature
1.710
1.685
5%
1.660
1.635
1.610
1.585
7.5%
10%
1.560
1.535
12.5%
1.510
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80 100
2902 G05
– ADJ Threshold Voltage
vs Temperature
0.018
0.012
0.006
0
–0.006
–0.012
–0.018
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80 100
2902 G08
IV2 vs Temperature
1.5
V1 = 5V
1.4 V2 = 3.3V
1.3
V3 = 2.5V
V4 = 1.8V
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
– 60 –40 – 20 0 20 40 60 80 100
TEMPERATURE (°C)
2902 G11
1.5V Threshold Voltage
vs Temperature
1.425
1.405
5%
1.385
1.365
7.5%
1.345
1.325
10%
1.305
1.285
12.5%
1.265
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80 100
2902 G06
VREF vs Temperature
1.228
1.216
5%
1.204
1.192
1.180
7.5%
1.168
1.156
1.144
10%
1.132
1.112
12.5%
1.108
1.096
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80 100
2902 G09
IV3 vs Temperature
1.1
V1 = 5V
1.0 V2 = 3.3V
0.9
V3 = 2.5V
V4 = 1.8V
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
– 60 –40 – 20 0 20 40 60 80 100
TEMPERATURE (°C)
2902 G12
2902f
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