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
s
s
s
s
s
s
s
s
s
s
s
s
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
s
s
s
s
s
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
LTC2902
ABSOLUTE
(Notes 1, 2, 3)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
COMP3
COMP1
V3
V1
CRT
RST
T0
RDIS
1
2
3
4
5
6
7
8
16 COMP2
15 COMP4
14 V2
13 V4
12 V
REF
11 V
PG
10 GND
9
T1
V1, V2, V3, V4, V
PG
..................................... – 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 (V
CC
+ 0.3V)
CRT ............................................. – 0.3V to (V
CC
+ 0.3V)
V
REF
............................................. – 0.3V to (V
CC
+ 0.3V)
Reference Load Current (I
VREF
) ............................
±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
ORDER PART
NUMBER
LTC2902-1CGN
LTC2902-2CGN
LTC2902-1IGN
LTC2902-2IGN
GN16 PART MARKING
29021
29022
29021I
29022I
GN PACKAGE
16-LEAD PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 130°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
SYMBOL
V
RT50
PARAMETER
5V, 5% Reset Threshold
5V, 7.5% Reset Threshold
5V, 10% Reset Threshold
5V, 12.5% Reset Threshold
3.3V, 5% Reset Threshold
3.3V, 7.5% Reset Threshold
3.3V, 10% Reset Threshold
3.3V, 12.5% Reset Threshold
3V, 5% Reset Threshold
3V, 7.5% Reset Threshold
3V, 10% Reset Threshold
3V, 12.5% Reset Threshold
2.5V, 5% Reset Threshold
2.5V, 7.5% Reset Threshold
2.5V, 10% Reset Threshold
2.5V, 12.5% Reset Threshold
1.8V, 5% Reset Threshold
1.8V, 7.5% Reset Threshold
1.8V, 10% Reset Threshold
1.8V, 12.5% Reset Threshold
1.5V, 5% Reset Threshold
1.5V, 7.5% Reset Threshold
1.5V, 10% Reset Threshold
1.5V, 12.5% Reset Threshold
ADJ, 5% Reset Threshold
ADJ, 7.5% Reset Threshold
ADJ, 10% Reset Threshold
ADJ, 12.5% Reset Threshold
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, unless otherwise noted. (Note 3)
CONDITIONS
V1 Input Threshold
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
MIN
4.600
4.475
4.350
4.225
3.036
2.954
2.871
2.789
2.760
2.685
2.610
2.535
2.300
2.238
2.175
2.113
1.656
1.611
1.566
1.521
1.380
1.343
1.305
1.268
0.492
0.479
0.466
0.453
TYP
4.675
4.550
4.425
4.300
3.086
3.003
2.921
2.838
2.805
2.730
2.655
2.580
2.338
2.275
2.213
2.150
1.683
1.638
1.593
1.548
1.403
1.365
1.328
1.290
0.500
0.487
0.473
0.460
MAX
4.750
4.625
4.500
4.375
3.135
3.053
2.970
2.888
2.850
2.775
2.700
2.625
2.375
2.313
2.250
2.188
1.710
1.665
1.620
1.575
1.425
1.388
1.350
1.313
0.508
0.494
0.481
0.467
UNITS
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
2902f
V
RT33
V1, V2 Input Threshold
V
RT30
V2 Input Threshold
V
RT25
V2, V3 Input Threshold
V
RT18
V3, V4 Input Threshold
V
RT15
V3, V4 Input Threshold
V
RTA
V3, V4 Input Threshold
2
U
W
U
U
W W
W
LTC2902
ELECTRICAL CHARACTERISTICS
SYMBOL
V
RTAN
V
CC
V
CCMINP
V
CCMINC
V
REF
PARAMETER
– ADJ Reset Threshold
Minimum Internal Operating Voltage
Minimum Required for Programming
Minimum Required for Comparators
Reference Voltage
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, unless otherwise noted. (Note 3)
CONDITIONS
V4 Input Threshold
RST, COMPX in Correct Logic State;
V
CC
Rising Prior to Program
V
CC
Rising
V
CC
Falling
V
CC
≥
2.3V, I
VREF
=
±1mA,
C
REF
≤
1000pF
T0 Low, T1 Low
T0 Low, T1 High
T0 High, T1 Low
T0 High, T1 High
V
CC
≥
V
CCMINP
V
PG
= V
REF
V1 = 5V, I
VREF
= 12µA, (Note 4)
V2 = 3.3V
V3 = 2.5V
V3 = 0.55V (ADJ Mode)
V4 = 1.8V
V4 = 0.55V (ADJ Mode)
V4 = –0.05V (–ADJ Mode)
V
CRT
= 0V
V
CRT
= 1.3V
C
RT
= 1500pF
V
X
Less Than Reset Threshold V
RTX
by More Than 1%
I
SINK
= 2.5mA; V1 = 3V, V2 = 3V;
V3, V4 = 0V; V
PG
= 0V
I
SINK
= 100µA; V2 = 1V; V1, V3, V4 = 0V
I
SINK
= 100µA; V1 = 1V; V2, V3, V4 = 0V
V
OH
V
OH
Output Voltage High RST, COMPX (Note 5)
Output Voltage High RST (LTC2902-2)
(Note 6)
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
I
SOURCE
= 1µA
I
SOURCE
= 200µA
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
MIN
– 18
TYP
0
MAX
18
1
2.42
2.32
UNITS
mV
V
V
V
V
V
V
V
V
nA
µA
µA
µA
nA
µA
nA
nA
µA
µA
ms
µs
1.192
1.160
1.128
1.096
0
1.210
1.178
1.146
1.113
1.228
1.195
1.163
1.130
V
REF
±20
V
PG
I
VPG
I
V1
I
V2
I
V3
I
V4
Programming Voltage Range
V
PG
Input Current
V1 Input Current
V2 Input Current
V3 Input Current
V4 Input Current
43
0.8
0.52
–15
0.34
–15
–15
–1.4
10
5
–2
20
7
150
0.15
0.05
0.05
V2 – 1
0.8 • V2
75
2
1.2
15
0.8
15
15
–2.6
30
9
q
q
q
q
q
q
I
CRT(UP)
I
CRT(DN)
t
RST
t
UV
V
OL
CRT Pull-Up Current
CRT Pull-Down Current
Reset Time-Out Period
V
X
Undervoltage Detect to RST or COMPX
Output Voltage Low RST, COMPX
0.4
0.3
0.3
V
V
V
V
V
Digital Inputs T0, T1, RDIS
V
IL
V
IH
I
INTOL
V
IL
V
IH
I
RDIS
V
CC
= 3.3V to 5.5V
V
CC
= 3.3V to 5.5V
T0 = 0V, T1 = V
CC
V
CC
= 3.3V to 5.5V
V
CC
= 3.3V to 5.5V
V
RDIS
= 0V
q
q
q
q
q
0.3V
CC
0.7V
CC
±0.1
0.4
1.6
–10
±1
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 (V
CC
).
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 V
OH
voltages greater than V2.
Note 6:
The push-pull RST output pin on the LTC2902-2 is
actively
pulled up
to V2.
2902f
3
LTC2902
TEST CIRCUITS
V1
V2
V3
V4
RST
LTC2902-1 OR COMPX
I
SOURCE
1µA
LTC2902-1
V1
V2
V3
V4
2902 F02
RST
OR COMPX
I
SINK
2.5mA,
100µA
V1
V2
V3
V4
LTC2902-2 RST
I
SOURCE
200µA
2902 F01
2902 F03
Figure 1. RST, COMPX V
OH
Test
Figure 2. RST, COMPX V
OL
Test
Figure 3. Active Pull-Up RST V
OH
Test
TI I G DIAGRA
TYPICAL PERFOR A CE CHARACTERISTICS
5V Threshold Voltage
vs Temperature
4.75
4.70
3.135
5%
3.100
THRESHOLD VOLTAGE, V
RT33
(V)
THRESHOLD VOLTAGE, V
RT50
(V)
4.65
4.60
4.55
4.50
4.45
4.40
4.35
4.30
4.25
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
12.5%
10%
7.5%
3.065
3.030
2.995
2.960
2.925
2.890
2.855
2.820
2.785
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
12.5%
10%
7.5%
THRESHOLD VOLTAGE, V
RT30
(V)
4
U W
W
V
X
Monitor Timing
V
RTX
t
UV
RST
t
RST
1.5V
V
X
2902 TD
UW
COMPX
3.3V Threshold Voltage
vs Temperature
2.850
5%
2.815
2.780
2.745
2.710
2.675
2.640
2.605
2.570
3V Threshold Voltage
vs Temperature
5%
7.5%
10%
12.5%
2.535
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
2902 G01
2902 G02
2902 G03
2902f
LTC2902
TYPICAL PERFOR A CE CHARACTERISTICS
2.5V Threshold Voltage
vs Temperature
2.375
2.350
5%
THRESHOLD VOLTAGE, V
RT18
(V)
1.710
1.685
1.660
7.5%
1.635
1.610
1.585
1.560
1.535
1.510
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
12.5%
10%
THRESHOLD VOLTAGE, V
RT25
(V)
2.325
2.300
2.275
2.250
2.225
2.200
2.175
2.150
2.125
2.100
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
12.5%
10%
7.5%
THRESHOLD VOLTAGE, V
RT15
(V)
ADJ Threshold Voltage
vs Temperature
0.508
0.503
5%
THRESHOLD VOLTAGE, V
RTAN
(V)
0.012
0.006
0.018
THRESHOLD VOLTAGE, V
RTA
(V)
0.498
0.493
0.488
0.483
0.478
0.473
0.468
0.463
0.458
0.453
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
12.5%
10%
7.5%
V
REF
(V)
I
V1
vs Temperature
100
V1 = 5V
90 V2 = 3.3V
V3 = 2.5V
80
V4 = 1.8V
70
I
V2
(µA)
I
V1
(µA)
50
40
30
20
10
0
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
1.0
0.9
0.8
0.7
0.6
0.5
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
I
V3
(µA)
60
U W
1.8V Threshold Voltage
vs Temperature
1.425
5%
1.405
1.385
1.365
1.345
1.5V Threshold Voltage
vs Temperature
5%
7.5%
10%
1.325
1.305
1.285
1.265
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
12.5%
2902 G04
2902 G05
2902 G06
– ADJ Threshold Voltage
vs Temperature
1.228
1.216
1.204
1.192
1.180
1.168
1.156
1.144
1.132
–0.012
–0.018
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
1.112
1.108
80
100
V
REF
vs Temperature
5%
7.5%
0
–0.006
10%
12.5%
1.096
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
2902 G07
2902 G08
2902 G09
I
V2
vs Temperature
1.5
V1 = 5V
1.4 V2 = 3.3V
V3 = 2.5V
1.3
V4 = 1.8V
1.2
1.1
1.1
I
V3
vs Temperature
V1 = 5V
1.0 V2 = 3.3V
V3 = 2.5V
0.9
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
TEMPERATURE (°C)
80
100
2902 G10
2902 G11
2902 G12
2902f
5
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