FEATURES
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LTC2931
Configurable Six Supply
Monitor with Adjustable Reset
and Watchdog Timers
DESCRIPTION
The LTC
®
2931 is a configurable supply monitor for
systems with up to six supply voltages. One of 16 preset or
adjustable voltage monitor combinations can be selected
using an external resistive divider connected to the mode
select pin. The preset voltage thresholds are accurate
to ±1.5% over temperature. The LTC2931 also features
adjustable inputs with a 0.5V nominal threshold. All six
open-drain voltage comparator outputs are connected to
separate pins for individual supply monitoring.
The reset and watchdog timeout periods are adjustable
using external capacitors. 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. Each status output has
a weak internal pull-up and may be externally pulled up
to a user defined voltage.
The 52μA supply current makes the LTC2931 ideal for
power conscious systems and it may be configured to
monitor fewer than six inputs.
L,
LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 6967591, 7239251, 7119714.
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Simultaneously Monitors Six Supplies
16 User Selectable Combinations of
5V, 3.3V, 3V, 2.5V, 1.8V, 1.5V and ± Adjustable
Voltage Thresholds
Guaranteed Threshold Accuracy: ±1.5%
Adjustable Reset and Watchdog Timeout
Low Supply Current: 52μA
Comparator/Monitor Output for Each Supply
Power Supply Glitch Immunity
Guaranteed
RST
for V
CC
≥ 1V
High Temperature Operation to 125°C
20-Lead TSSOP Package
APPLICATIONS
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Desktop and Notebook Computers
Multivoltage Systems
Telecom Equipment
Portable Battery-Powered Equipment
Network Servers
Automotive
TYPICAL APPLICATION
Six Supply Monitor 12V (ADJ), 5V, 3.3V, 2.5V, 1.8V, 1.2V (ADJ)
12V
5V
3.3V
2.5V
1.8V
1.2V
10k
2150k
1%
124k
1%
COMP1
COMP2
COMP3
COMP4
COMP5
V1
V2
0.1μF
0.1μF
100k
1%
100k
1% R1
59k
1%
R2
40.2k
1%
V3
V4
V5
V6
VREF
VPG
GND
CWT
C
WT
47nF
CRT
RST
2931 TA01
Voltage Threshold Configuration Table
V1 (V) V2 (V) V3 (V) V4 (V) V5 (V) V6 (V)
5.0
3.3
2.5
1.8
ADJ
ADJ
5.0
3.3
2.5
1.5
ADJ
ADJ
5.0
3.3
2.5
ADJ
ADJ
ADJ
5.0
3.3
1.8
ADJ
ADJ
ADJ
5.0
3.3
1.8
–ADJ ADJ
ADJ
5.0
3.3
ADJ
ADJ
ADJ
ADJ
5.0
3.3
ADJ –ADJ ADJ
ADJ
5.0
3.0
2.5
ADJ
ADJ
ADJ
5.0
3.0
1.8
ADJ
ADJ
ADJ
5.0
3.0
ADJ
ADJ
ADJ
ADJ
3.3
2.5
1.8
1.5
ADJ
ADJ
3.3
2.5
1.8
ADJ
ADJ
ADJ
3.3
2.5
1.8
–ADJ ADJ
ADJ
3.3
2.5
1.5
ADJ
ADJ
ADJ
3.3
2.5
ADJ
ADJ
ADJ
ADJ
3.3
2.5
ADJ –ADJ ADJ
ADJ
SYSTEM
LOGIC
POWER
GOOD
COMP6
WDI
LTC2931
WDO
t
RST
= 94ms
t
WD
= 940ms
C
RT
47nF
2931fb
1
LTC2931
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2, 3)
PIN CONFIGURATION
TOP VIEW
COMP5
V5
COMP3
COMP1
V3
V1
CRT
RST
WDO
1
2
3
4
5
6
7
8
9
20 COMP6
19 V6
18 COMP2
17 COMP4
16 V2
15 V4
14 VREF
13 VPG
12 GND
11 CWT
V1, V2, V3, V4, V5, V6, VPG ........................ –0.3V to 7V
RST
, COMP1-6............................................ –0.3V to 7V
CWT,
WDO
.................................................... –0.3V to 7V
CRT, VREF WDI .............................–0.3V to (V
CC
+ 0.3V)
,
Reference Load Current (I
VREF
) ..............................±1mA
V4 Input Current (–ADJ Mode) ..............................–1mA
RST
,
WDO,
COMP1-6 Currents ...........................±10mA
Operating Temperature Range
LTC2931C ................................................ 0°C to 70°C
LTC2931I.............................................. –40°C to 85°C
LTC2931H .......................................... –40°C to 125°C
Storage Temperature Range................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
WDI 10
F PACKAGE
20-LEAD PLASTIC TSSOP
T
JMAX
= 130°C,
θ
JA
= 90°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC2931CF#PBF
LTC2931IF#PBF
LTC2931HF#PBF
TAPE AND REEL
LTC2931CF#TRPBF
LTC2931IF#TRPBF
LTC2931HF#TRPBF
PART MARKING
LTC2931F
LTC2931F
LTC2931F
PACKAGE DESCRIPTION
20-Lead Plastic TSSOP
20-Lead Plastic TSSOP
20-Lead Plastic TSSOP
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
This product is only offered in trays. For more information go to:
http://www.linear.com/packaging/
ELECTRICAL CHARACTERISTICS
SYMBOL
V
CC
V
CCMINP
V
CCMINC
V
RT50
V
RT33
V
RT30
V
RT25
V
RT18
V
RT15
V
RTA
V
RTAN
PARAMETER
Minimum Internal Operating Voltage
Minimum Required for Mode Selection
Minimum Required for Comparators
5V, 5% Reset Threshold
3.3V, 5% Reset Threshold
3V, 5% Reset Threshold
2.5V, 5% Reset Threshold
1.8V, 5% Reset Threshold
1.5V, 5% Reset Threshold
ADJ Reset Threshold
–ADJ Reset Threshold
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, unless otherwise specified. (Note 3)
CONDITIONS
RST,
COMP
n
in Correct Logic State
V
CC
Rising
V
CC
Falling
V1 Input Threshold
V1, V2 Input Threshold
V2 Input Threshold
V2, V3 Input Threshold
V3, V4 Input Threshold
V3, V4 Input Threshold
V3, V4, V5, V6 Input Threshold
V4 Input Threshold
●
●
●
●
●
●
●
●
●
●
●
MIN
TYP
MAX
1
2.4
2.3
UNITS
V
V
V
V
V
V
V
V
V
mV
mV
4.600
3.036
2.760
2.300
1.656
1.380
492.5
–18
4.675
3.086
2.805
2.338
1.683
1.403
500
0
4.750
3.135
2.850
2.375
1.710
1.425
507.5
18
2931fb
2
LTC2931
ELECTRICAL CHARACTERISTICS
SYMBOL
V
REF
V
PG
I
VPG
I
V1
I
V2
I
V3
I
V4
PARAMETER
Reference Voltage
Mode Selection Voltage Range
VPG Input Current
V1 Input Current
V2 Input Current
V3 Input Current
V4 Input Current
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, unless otherwise specified. (Note 3)
CONDITIONS
V
CC
≥ 2.3V, I
VREF
= ±1mA,
C
REF
≤ 1000pF
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 = –0.02V (–ADJ Mode)
V5, V6 = 0.55V
V
CRT
= GND
V
CRT
= 1.3V
C
RT
= 1500pF
V
n
Less Than Reset Threshold by More
than 1%
I
SINK
= 3mA, V
CC
= 3V
I
SINK
= 100μA, V
CC
= 1V
V
COMPn
= GND
I
SINK
= 3mA
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
MIN
1.192
0
TYP
1.210
MAX
1.228
V
REF
±20
UNITS
V
V
nA
μA
μA
μA
nA
μA
nA
nA
nA
μA
μA
ms
μs
52
0.8
0.52
–15
0.34
–15
–15
–15
–1.4
10
2
–2
20
3
150
0.15
0.05
–2
V2-1
–1.4
10
20
1.6
–2
20
30
–6
0.15
75
2
1.2
15
0.8
15
15
15
–2.6
30
4
I
V5
, I
V6
I
CRT(UP)
I
CRT(DN)
t
RST
t
UV
V
OL
I
COMPn
V
OL
V
OH
I
CWT(UP)
I
CWT(DN)
t
WD
V
IH
V
IL
t
WP
I
WDI
V5, V6 Input Current
CRT Pull-Up Current
CRT Pull-Down Current
Reset Timeout Period
V
n
Undervoltage Detect to
RST
or
COMP
n
Voltage Output Low
RST,
COMP
n
COMP
n
Pull-Up Current
Voltage Output Low
WDO
0.4
0.3
–12
0.4
V
V
μA
V
V
Voltage Output High
RST, WDO,
COMP
n
I
SOURCE
= –1μA
(Note 5)
CWT Pull-Up Current
CWT Pull-Down Current
Watchdog Timeout Period
WDI Input Threshold High
WDI Input Threshold Low
WDI Input Pulse Width
WDI Pull-Up Current
V
CWT
= GND
V
CWT
= 1.3V
C
WT
= 1500pF
V
CC
= 3.3V to 5.5V
V
CC
= 3.3V to 5.5V
V
CC
= 3.3V
V
WDI
= 1V
–2.6
30
40
0.4
μA
μA
ms
V
V
ns
μA
150
–4
–10
–16
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device reliability
and lifetime.
Note 2:
All currents into pins are positive, all voltages are referenced to GND
unless otherwise noted.
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, WDO,
and COMP
n
have diode protected 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.
2931fb
3
LTC2931
TIMING DIAGRAMS
V
n
Monitor Timing
V
n
V
RT
t
UV
t
RST
RST
2931 TD
COMP
n
Watchdog Timing
t
RST
RST
WDI
t
WP
t < t
RST
WDO
t
RST
t
WD
t
WD
2931 TD2
t
RST
t
WD
2931fb
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LTC2931
TYPICAL PERFORMANCE CHARACTERISTICS
Normalized Threshold Voltages
vs Temperature
NORMALIZED THRESHOLD VOLTAGES (V/V)
1.015
THRESHOLD VOLTAGE, V
RTAN
(mV)
1.010
1.005
1.000
0.995
0.990
0.985
–50 –25
18
12
6
0
–6
–12
–18
–50 –25
V
REF
(V)
–ADJ Threshold Voltage
vs Temperature
1.228
1.222
1.216
1.210
1.204
1.198
V
REF
vs Temperature
50
25
75
0
TEMPERATURE (°C)
100
125
50
25
75
0
TEMPERATURE ( C)
100
125
1.192
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
2931 G01
2931 G02
2931 G03
Supply Current vs Temperature
70
V1 = 5V
V2 = 3.3V
65 V3 = 2.5V
V4 = 1.8V
V5 = V6 = 1V
60
I
V4
(A)
55
50
45
40
–50 –25
–100μ
–10μ
–1μ
–100n
–10n
–1n
I(V4) vs V4 in Negative
Adjust Mode
300
TYPICAL TRANSIENT DURATION ( s)
250
200
Transient Duration vs Comparator
Overdrive (V1,V2)
T
A
= 25 C
SUPPLY CURRENT, I
V1
( A)
125°C
RESET OCCURS ABOVE CURVE
150
100
50
0
90°C
25°C
50
25
75
0
TEMPERATURE ( C)
100
125
–100p
–300
–250
–200
–150 –100
V4 (mV)
–50
0
2931 G05
2931 G04
0.1
1
10
100
RESET COMPARATOR OVERDRIVE (% OF V
RTX
)
2931 G06
Transient Duration vs Comparator
Overdrive (V3, V4, V5, V6)
450
TYPICAL TRANSIENT DURATION ( s)
375
300
RESET OCCURS ABOVE CURVE
225
150
75
0
RST OUTPUT VOLTAGE (V)
T
A
= 25 C
6
5
4
3
2
1
0
RST
Output Voltage vs V1,
V
PG
= GND
WATCHDOG TIMEOUT PERIOD, t
WD
(ms)
T
A
= 25 C
10k PULL-UP FROM RST TO V1
36
34
32
30
28
26
Watchdog Timeout Period
vs Temperature
C
WT
= 1500pF
(SILVER MICA)
0.1
1
10
100
RESET COMPARATOR OVERDRIVE (% OF V
RTX
)
2931 G07
0
1
2
V1 (V)
3
4
5
2931 G08
24
–50 –25
50
25
75
0
TEMPERATURE ( C)
100
125
2931 G09
2931fb
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