LTC1727/LTC1728
Micropower Precision
Triple Supply Monitors
in 8-Lead MSOP and
5-Lead SOT-23 Packages
FeaTures
n
Monitors Three Inputs Simultaneously
LTC1727-5: 5V, 3.3V and ADJ
LTC1727-2.5: 2.5V, 3.3V and ADJ
LTC1728-5: 5V, 3.3V and ADJ
LTC1728-2.5: 2.5V, 3.3V and ADJ
LTC1728-1.8: 3V, 1.8V and ADJ
LTC1728-3.3: 3.3V, 1.8V and ADJ
n
±1.5% Threshold Accuracy Over Temperature
n
Very Low Supply Current: 10µA Typ
n
200ms Reset Time Delay
n
Active Low RESET Output
n
Power Supply Glitch Immunity
n
Guaranteed RESET for V
or V
n
n
n
CC5/VCC25/VCC18
LTC1727 Includes Monitor Output for Each Supply
LTC1727: 8-Lead MSOP and SO Packages
LTC1728: 5-Lead SOT-23 Package
≥ 1V
CC3
≥ 1V
applicaTions
n
Desktop Computers
n
Notebook Computers
n
Intelligent Instruments
n
Portable Battery-Powered Equipment
n
Network Servers
DescripTion
The LTC®1727 is a triple supply monitor intended for
systems with multiple supply voltages. Each supply monitor has its own open-drain output for individual supply
monitoring. A common open-drain reset output remains
low until all three supplies have been in compliance for
200ms. Tight 1.5% accuracy specifications and glitch
immunity ensure reliable reset operation without false
triggering.
The LTC1728 is functionally identical to the LTC1727
without the individual monitor outputs.
The RST output is guaranteed to be in the correct state
for V
CC5/VCC25/VCC18
or V
LTC1728 may also be configured to monitor any one or
two V
inputs instead of three, depending on system
CC
requirements.
Very low (10µA typical) supply current makes the LTC1727/
LTC1728 ideal for power conscious systems.
The LTC1727 is available in an 8-lead MSOP or SO package and the LTC1728 is available in a 5-lead SOT-23
package.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
down to 1V. The LTC1727/
CC3
Typical applicaTion
3.3V
DC/DC
CONVERTER
5V
1.8V
0.1µF
0.1µF
5 1
4
R1
61.9k
3
1%
R2
100k
1%
V
CC3
LTC1728-5
V
CC5
V
CCA
RST
GND
1727/28 TA01
SYSTEM
LOGIC
2
ADJUSTABLE
SUPPLY
Triple Supply Monitor with Power Good Output
(3.3V, 2.5V and Adjustable)
R3
LTC1727-2.5
1
3.3V
2.5V
R1
R2
V
CC3
2
COMP25
V
CC25
3
V
CCA
4
GND
COMP3
RST
COMPA
8
7
6
5
1727/28 TA08
10k
R4
10k
POWER
GOOD
SYSTEM
RESET
17278fb
1
LTC1727/LTC1728
absoluTe MaxiMuM raTings
V
, V
CC3
CC5/VCC25/VCC18
, V
CCA ........................
–0.3V to 7V
(Notes 1. 2)
RST ............................................................. – 0.3V to 7V
COMPA, COMP3, COMP25/COMP5
(MS8 and SO-8 Only) ............................. – 0.3V to 7V
pin conFiguraTion
TOP VIEW
TOP VIEW
V
1
CC3
V
CC5/VCC25
2
3
V
CCA
4
GND
MS8 PACKAGE
8-LEAD PLASTIC MSOP
= 125°C, θJA = 200°C/W
T
JMAX
ORDER
PART NUMBER
8
COMP3
7
COMP25/COMP5
6
RST
5
COMPA
MS8
PART MARKING
V
1
CC3
V
/
CC5
2
V
CC25
V
3
CCA
GND
4
S8 PACKAGE
8-LEAD PLASTIC SO
= 125°C, θJA = 150°C/W
T
JMAX
ORDER
PART NUMBER
Operating Temperature Range
LTC1727/LTC1728E (Note 3) ............... – 40°C to 85°C
LTC1728H ..........................................– 40°C to 125°C
LTC1727I..............................................– 40°C to 85°C
Storage Temperature Range .................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec) ................. 300°C
COMP3
8
COMP25/
7
COMP5
RST
6
COMPA
5
S8
PART MARKING
RST 1
GND 2
V
ORDER
PART NUMBER
TOP VIEW
3
CCA
S5 PACKAGE
5-LEAD PLASTIC SOT-23
= 125°C, θJA = 250°C/W
T
JMAX
PART MARKING
5 V
4
V
V
V
CC3
CC5
CC25
CC18
S5
/
/
LTC1727EMS8-2.5
LTC1727EMS8-5
LTHY
LTHX
LTC1727ES8-2.5
LTC1727IS8-2.5
LTC1727ES8-5
LTC1727IS8-5
172725
727I25
17275
172715
LTC1728ES5-1.8
LTC1728ES5-2.5
LTC1728ES5-3.3
LTC1728ES5-5
LTC1728HS5-5
LTPH
LTIA
LTY P
LTHZ
LTHZ
Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
All except LTC1728-1.8/LTC1728-3.3. The l denotes specifications which
elecTrical cHaracTerisTics
apply over the full operating temperature range, otherwise specifications are at TA = 25°C. V
V
CC25
= 2.5V, V
CCA
= V
unless otherwise noted.
CC3
= 3.3V, V
CC3
CC5
= 5V,
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
RT3
V
RT5
V
RT25
V
RTA
V
CCOP
V
CCOPAVCC3
Reset Threshold V
Reset Threshold V
Reset Threshold V
Reset Threshold V
V
, V
CC3
CC5/VCC25
, V
CC5/VCC25
V
CC3
CC5
CC25
CCA
Input Threshold
CC3
V
Input Threshold (5V Version)
CC5
V
Input Threshold (2.5V Version)
CC25
V
Input Threshold
CCA
Operating Voltage RST, COMP3, COMP5, COMP25 in Correct Logic State
Operating Voltage Minimum Supply Voltage to Guarantee COMPA
l
3.036 3.086 3.135 V
l
4.600 4.675 4.750 V
l
2.300 2.338 2.375 V
l
0.985 1.000 1.015 V
l
1 7 V
l
2 2.3 V
in Correct Logic State
2
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LTC1727/LTC1728
elecTrical cHaracTerisTics
All except LTC1728-1.8/LTC1728-3.3. The l denotes specifications which
apply over the full operating temperature range, otherwise specifications are at TA = 25°C. V
V
= 2.5V, V
CC25
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
I
VCC3
I
VCC25
I
VCC5
I
VCCA
t
RST
t
UV
V
V
V
V
Reset Pulse Width RST Low with 10k Pull-Up to V
VCC Undervoltage Detect to RST
or COMPX
V
OL
V
OH
Output Voltage Low, RST, COMPX I
Output Voltage High, RST, COMPX (Note 6) I
LTC1727-5/LTC1728-5 Only
V
OVR
V
= V
CCA
Supply Current V
CC3
Supply Current V
CC25
Supply Current V
CC5
Input Current V
CCA
unless otherwise noted.
CC3
CC5/VCC25
V
CC5/VCC25
CC25
CC5
CCA
–40°C < T
–40°C < T
V
CC5
Threshold V
SINK
I
SINK
I
SINK
I
SINK
SOURCE
Reset Override Voltage (Note 7) Override V
CC5
> V
< V
< V
, V
CC3
= 5V, V
CC3
= 1V
< 125°C
A
< 125°C
A
, V
, V
CC25
CC3
by More Than 1% (Note 5)
RT
= 2.5mA, V
= 100µA, V
= 100µA, V
= 100µA, V
= 1µA
Ability to Assert RST V
CC5
CC3
, V
CC3
= 3.3V (Note 4)
CC3
= 2.5V (Note 4)
CC25
< V
CC5
or V
CCA
= 3V, V
CC3
= 1V, V
CC3
= 0V, V
CC3
= 1V, V
CC3
(Note 5)
CC3
Less Than Reset
CC5/VCC25
CC5/VCC25
CC5/VCC25
CC5/VCC25
= 0V
= 0V
= 1V
= 1V
= 3.3V, V
CC3
= 5V,
CC5
l
l
l
l
l
l
l
l
–15
–20
140
140
1
10
1 2 µA
10 20 µA
0
0
200 280
110 µs
l
l
l
l
l
V
– 1 V
CC3
0.15
0.05
0.05
0.05
±0.025 V
CC3
2
20
15
50
350
0.4
0.3
0.3
0.3
µA
µA
nA
nA
ms
ms
V
V
V
V
LTC1728-1.8 The l denotes specifications which apply over the full operating temperature range, otherwise specifications are at
TA = 25°C. V
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
RT3
V
RT18
V
RTA
V
CCOP
I
VCC3
I
VCC18
I
VCCA
t
RST
t
UV
V
OL
V
OH
= 3V, V
CC3
Reset Threshold V
Reset Threshold V
Reset Threshold V
V
, V
CC3
V
Supply Current V
CC3
V
Supply Current V
CC18
V
Input Current V
CCA
= 1.8V, V
CC18
CC3
CC18
CCA
Operating Voltage RST in Correct Logic State
CC18
CCA
= V
unless otherwise noted.
CC3
V
Input Threshold
CC3
V
Input Threshold
CC18
V
Input Threshold
CCA
> V
CC18
V
< V
CC18
< V
CC18
= 1V
CCA
CC3
CC3
CC3
, V
, V
Reset Pulse Width RST Low (Note 5)
VCC Undervoltage Detect to RST V
Output Voltage Low, RST I
Output Voltage High, RST I
, V
CC18
CC3
Threshold V
= 2.5mA, V
SINK
I
= 100µA, V
SINK
I
= 100µA, V
SINK
I
= 100µA, V
SINK
= 1µA (Note 6)
SOURCE
or V
by More Than 1%
RT
= 3V (Note 4)
CC3
= 1.8V (Note 4)
CC18
Less Than Reset (Note 5)
CCA
CC3
CC3
CC3
CC3
= 3V, V
= 1V, V
= 0V, V
= 1V, V
CC18
CC18
CC18
CC18
= 0V
= 0V
= 1V
= 1V
l
2.760 2.805 2.850 V
l
1.656 1.683 1.710 V
l
0.985 1.000 1.015 V
l
1 7 V
l
l
l
l
–15 0 15 nA
l
140 200 280 ms
1
10
2
20
1 2 µA
110 µs
l
l
l
l
l
V
CC3
0.15
0.05
0.05
0.05
0.4
0.3
0.3
0.3
– 1 V
µA
µA
V
V
V
V
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3
LTC1727/LTC1728
elecTrical cHaracTerisTics
LTC1728-3.3 The l denotes specifications which apply over the full operating temperature range, otherwise specifications are at
TA = 25°C. V
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
RT3
V
RT18
V
RTA
V
CCOP
I
VCC3
I
VCC18
I
VCCA
t
RST
t
UV
V
OL
V
OH
= 3.3V, V
CC3
Reset Threshold V
Reset Threshold V
Reset Threshold V
V
, V
CC3
CC18
V
Supply Current V
CC3
V
Supply Current V
CC18
V
Input Current V
CCA
CC18
CC3
CC18
CCA
= 1.8V, V
CCA
= V
unless otherwise noted.
CC3
V
Input Threshold
CC3
V
Input Threshold
CC18
V
Input Threshold
CCA
Operating Voltage RST in Correct Logic State
> V
CC18
CC18
CC18
CCA
< V
< V
= 1V
CC3
CC3
CC3
, V
, V
CC3
CC18
V
Reset Pulse Width RST Low (Note 5)
VCC Undervoltage Detect to RST V
Output Voltage Low, RST I
Output Voltage High, RST I
, V
CC18
CC3
Threshold V
= 2.5mA, V
SINK
I
= 100µA, V
SINK
I
= 100µA, V
SINK
I
= 100µA, V
SINK
= 1µA (Note 6)
SOURCE
or V
by More Than 1%
RT
= 3.3V (Note 4)
= 1.8V (Note 4)
Less Than Reset (Note 5)
CCA
= 3.3V, V
CC3
= 1V, V
CC3
= 0V, V
CC3
= 1V, V
CC3
CC18
CC18
CC18
CC18
= 0V
= 0V
= 1V
= 1V
l
3.036 3.086 3.135 V
l
1.656 1.683 1.710 V
l
0.985 1.000 1.015 V
l
1 7 V
l
l
l
l
–15 0 15 nA
l
140 200 280 ms
1
10
2
20
1 2 µA
110 µs
l
l
l
l
l
V
CC3
0.15
0.05
0.05
0.05
0.4
0.3
0.3
0.3
– 1 V
µA
µA
V
V
V
V
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 voltage values are with respect to GND.
Note 3: The LTC1727E/LTC1728E are guaranteed to meet specified
performance from 0°C to 70°C and are designed, characterized and
assured to meet the extended temperature limits of –40°C to 85°C
but are not tested at these temperatures.
Note 4: Both V
CC3
and V
CC5/VCC25/VCC18
can act as the supply depending
on which pin has the greatest potential.
Note 5: Measured from when input passes through the input threshold
(V
) until RST or COMPX passes through 1.5V.
RTX
Note 6: The output pins RST and COMPX have internal pull-ups to V
CC3
of
typically 6µA. However, external pull-up resistors may be used when faster
rise times are required or for V
Note 7: The V
reset override voltage is valid for an operating range less
CC5
voltages greater than V
OH
CC3
.
than approximately 4.15V. Above this point the override is turned off and
the V
pin functions normally.
CC5
4
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Typical perForMance cHaracTerisTics
LTC1727/LTC1728
Input Current
V
CCA
vs Input Voltage
2.0
TA = 25°C
1.5
1.0
0.5
0
–0.5
INPUT CURRENT (nA)
–1.0
–1.5
–2.0
0.80 0.85 0.95 1.05 1.15
0.90
1
INPUT VOLTAGE (V)
Reset Pulse Width
vs Temperature
280
260
(ms)
240
RST
220
200
180
RESET PULSE WIDTH, t
160
140
–60 –40
–20 20 40 800 100
TEMPERATURE (°C)
1.10
60
1727/28 G01
1727/28 G04
1.015
(V)
1.010
RTA
1.005
1.000
0.995
THRESHOLD VOLTAGE, V
0.990
CCA
V
1.20
0.985
(mA)
SINK
I
V
Threshold Voltage
CCA
vs Temperature
–40 0
–60
–20 20
TEMPERATURE (°C)
RST, COMPX I
vs Supply Voltage
10
TA = 25°C
9
8
7
6
5
4
3
2
1
0
0
1
Typical Transient Duration
vs Comparator Overdrive
SINK
450
400
350
300
250
200
150
100
TYPICAL TRANSIENT DIRATION (µs)
50
0
40
60
80
100
1727/28 G02
0.1
RESET COMPARATOR OVERDRIVE VOLTAGE (% OF VCC)
I
vs Temperature
VCC25
RESET OCCURS
ABOVE CURVE
1 10 100
TA = 25°C
1727/28 G03
(LTC1727-2.5/LT1728-2.5)
1.5
V
= 3.3V
CC3
1.4
1.1
(µA)
VCC25
I
0.5
1.3
1.2
1.0
0.9
0.8
0.7
0.6
VOL = 0.4V
VOL = 0.2V
(V)
5
1727/28 G05
6
3 4
2
V
OR V
CC3
CC5
V
CC25
V
CCA
–60
–40 0
= 2.5V
= 3.3V
–20
TEMPERATURE (°C)
80
20
60
40
100
1727/28 G06
I
vs Temperature (LTC1727-
VCC3
2.5/LTC1728-2.5/LTC1728-3.3)
15
V
= 3.3V
CC3
(µA)
VCC3
I
14
13
12
11
10
V
V
9
8
7
6
5
–60
= 2.5V
CC25
= 3.3V
CCA
–40 0
–20
20
TEMPERATURE (°C)
I
vs Temperature
VCC3
(LTC1727-5/LTC1728-5)
1.5
V
= 5V
CC5
1.4
1.3
1.2
1.1
(µA)
1.0
VCC3
I
0.9
0.8
0.7
80
60
40
100
1727/28 G07
0.5
0.6
–60
= 3.3V
V
CC3
= 3.3V
V
CCA
–40 0
–20
20
TEMPERATURE (°C)
40
80
60
100
1727/28 G08
I
vs Temperature
VCC5
(LTC1727-5/LTC1728-5)
15
V
= 5V
CC5
14
= 3.3V
V
CC3
= 3.3V
V
CCA
13
12
11
(µA)
10
VCC5
I
9
8
7
6
5
–60
–40 0
–20
TEMPERATURE (°C)
80
20
60
40
100
1727/28 G09
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