FeaTures
n
LTC1727/LTC1728
Micropower Precision
Triple Supply Monitors
in 8-Lead MSOP and
5-Lead SOT-23 Packages
DescripTion
The LTC
®
1727 is a triple supply monitor intended for
systems with multiple supply voltages. Each supply moni-
tor 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
/V
CC25
/V
CC18
or V
CC3
down to 1V. The LTC1727/
LTC1728 may also be configured to monitor any one or
two V
CC
inputs instead of three, depending on system
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 pack-
age 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.
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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
±1.5% Threshold Accuracy Over Temperature
Very Low Supply Current: 10µA Typ
200ms Reset Time Delay
Active Low RESET Output
Power Supply Glitch Immunity
Guaranteed
RESET
for V
CC3
≥ 1V
or V
CC5
/V
CC25
/V
CC18
≥ 1V
LTC1727 Includes Monitor Output for Each Supply
LTC1727: 8-Lead MSOP and SO Packages
LTC1728: 5-Lead SOT-23 Package
applicaTions
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Desktop Computers
Notebook Computers
Intelligent Instruments
Portable Battery-Powered Equipment
Network Servers
Typical applicaTion
DC/DC
CONVERTER
3.3V
5V
1.8V
SYSTEM
LOGIC
Triple Supply Monitor with Power Good Output
(3.3V, 2.5V and Adjustable)
1
2
3
R2
4
LTC1727-2.5
V
CC3
COMP3
8
7
6
5
1727/28 TA08
5
V
CC3
V
CC5
V
CCA
RST
1
3.3V
2.5V
2
ADJUSTABLE
SUPPLY
R1
R3
10k
R4
10k
LTC1728-5
4
0.1µF
0.1µF
R1
61.9k
1% 3
R2
100k
1%
POWER
GOOD
SYSTEM
RESET
V
CC25
COMP25
V
CCA
GND
RST
COMPA
GND
1727/28 TA01
17278fb
1
LTC1727/LTC1728
absoluTe MaxiMuM raTings
(Notes 1. 2)
V
CC3
, V
CC5
/V
CC25
/V
CC18
, V
CCA ........................
– 0.3V to 7V
RST
............................................................. – 0.3V to 7V
COMPA, COMP3, COMP25/COMP5
(MS8 and SO-8 Only) ............................. – 0.3V to 7V
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
pin conFiguraTion
TOP VIEW
TOP VIEW
V
CC3
V
CC5
/V
CC25
V
CCA
GND
1
2
3
4
8
7
6
5
COMP3
COMP25/COMP5
RST
COMPA
V
CC3
1
V
CC5
/
2
V
CC25
V
CCA
3
GND 4
8
7
6
5
COMP3
COMP25/
COMP5
RST
COMPA
TOP VIEW
RST
1
GND 2
V
CCA
3
5 V
CC3
V
CC5
/
4 V
CC25
/
V
CC18
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 200°C/W
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 150°C/W
S5 PACKAGE
5-LEAD PLASTIC SOT-23
T
JMAX
= 125°C,
θ
JA
= 250°C/W
ORDER
PART NUMBER
LTC1727EMS8-2.5
LTC1727EMS8-5
MS8
ORDER
PART MARKING PART NUMBER
LTHY
LTHX
LTC1727ES8-2.5
LTC1727IS8-2.5
LTC1727ES8-5
LTC1727IS8-5
S8
PART MARKING
172725
727I25
17275
172715
ORDER
PART NUMBER
LTC1728ES5-1.8
LTC1728ES5-2.5
LTC1728ES5-3.3
LTC1728ES5-5
LTC1728HS5-5
S5
PART MARKING
LTPH
LTIA
LTYP
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
apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C. V
CC3
= 3.3V, V
CC5
= 5V,
V
CC25
= 2.5V, V
CCA
= V
CC3
unless otherwise noted.
SYMBOL PARAMETER
V
RT3
V
RT5
V
RT25
V
RTA
V
CCOP
V
CCOPA
Reset Threshold V
CC3
Reset Threshold V
CC5
Reset Threshold V
CC25
Reset Threshold V
CCA
V
CC3
, V
CC5
/V
CC25
Operating Voltage
V
CC3
, V
CC5
/V
CC25
Operating Voltage
CONDITIONS
V
CC3
Input Threshold
V
CC5
Input Threshold (5V Version)
V
CC25
Input Threshold (2.5V Version)
V
CCA
Input Threshold
RST,
COMP3, COMP5, COMP25 in Correct Logic State
Minimum Supply Voltage to Guarantee COMPA
in Correct Logic State
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elecTrical cHaracTerisTics
MIN
3.036
4.600
2.300
0.985
1
TYP
3.086
4.675
2.338
1.000
2
MAX UNITS
3.135
4.750
2.375
1.015
7
2.3
V
V
V
V
V
V
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2
LTC1727/LTC1728
elecTrical cHaracTerisTics
SYMBOL PARAMETER
I
VCC3
I
VCC25
I
VCC5
I
VCCA
t
RST
t
UV
V
OL
V
CC3
Supply Current
V
CC25
Supply Current
V
CC5
Supply Current
V
CCA
Input Current
Reset Pulse Width
V
CC
Undervoltage Detect to
RST
or COMPX
Output Voltage Low,
RST,
COMPX
All except LTC1728-1.8/LTC1728-3.3. The
l
denotes specifications which
apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C. V
CC3
= 3.3V, V
CC5
= 5V,
V
CC25
= 2.5V, V
CCA
= V
CC3
unless otherwise noted.
CONDITIONS
V
CC5
/V
CC25
> V
CC3
V
CC5
/V
CC25
< V
CC3
, V
CC3
= 3.3V (Note 4)
V
CC25
< V
CC3
, V
CC25
= 2.5V (Note 4)
V
CC5
= 5V, V
CC3
< V
CC5
V
CCA
= 1V
–40°C < T
A
< 125°C
RST
Low with 10k Pull-Up to V
CC3
(Note 5)
–40°C < T
A
< 125°C
V
CC5
, V
CC25
, V
CC3
or V
CCA
Less Than Reset
Threshold V
RT
by More Than 1% (Note 5)
I
SINK
= 2.5mA, V
CC3
= 3V, V
CC5
/V
CC25
= 0V
I
SINK
= 100µA, V
CC3
= 1V, V
CC5
/V
CC25
= 0V
I
SINK
= 100µA, V
CC3
= 0V, V
CC5
/V
CC25
= 1V
I
SINK
= 100µA, V
CC3
= 1V, V
CC5
/V
CC25
= 1V
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V
CC3
– 1
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MIN
TYP
1
10
1
10
MAX UNITS
2
20
2
20
15
50
280
350
µA
µA
µA
µA
nA
nA
ms
ms
µs
0.4
0.3
0.3
0.3
V
V
V
V
V
–15
–20
140
140
0
0
200
110
0.15
0.05
0.05
0.05
Output Voltage High,
RST,
COMPX (Note 6) I
SOURCE
= 1µA
LTC1727-5/LTC1728-5 Only
V
OVR
V
CC5
Reset Override Voltage (Note 7)
Override V
CC5
Ability to Assert RST
V
OH
V
CC3
±0.025
V
LTC1728-1.8 The
l
denotes specifications which apply over the full operating temperature range, otherwise specifications are at
T
A
= 25°C. V
CC3
= 3V, V
CC18
= 1.8V, V
CCA
= V
CC3
unless otherwise noted.
SYMBOL
V
RT3
V
RT18
V
RTA
V
CCOP
I
VCC3
I
VCC18
I
VCCA
t
RST
t
UV
V
OL
PARAMETER
Reset Threshold V
CC3
Reset Threshold V
CC18
Reset Threshold V
CCA
V
CC3
, V
CC18
Operating Voltage
V
CC3
Supply Current
V
CC18
Supply Current
V
CCA
Input Current
Reset Pulse Width
V
CC
Undervoltage Detect to
RST
Output Voltage Low,
RST
CONDITIONS
V
CC3
Input Threshold
V
CC18
Input Threshold
V
CCA
Input Threshold
RST
in Correct Logic State
V
CC18
> V
CC3
V
CC18
< V
CC3
, V
CC3
= 3V (Note 4)
V
CC18
< V
CC3
, V
CC18
= 1.8V (Note 4)
V
CCA
= 1V
RST
Low (Note 5)
V
CC18
, V
CC3
or V
CCA
Less Than Reset (Note 5)
Threshold V
RT
by More Than 1%
I
SINK
= 2.5mA, V
CC3
= 3V, V
CC18
= 0V
I
SINK
= 100µA, V
CC3
= 1V, V
CC18
= 0V
I
SINK
= 100µA, V
CC3
= 0V, V
CC18
= 1V
I
SINK
= 100µA, V
CC3
= 1V, V
CC18
= 1V
I
SOURCE
= 1µA (Note 6)
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MIN
2.760
1.656
0.985
1
TYP
2.805
1.683
1.000
1
10
1
MAX
2.850
1.710
1.015
7
2
20
2
15
280
UNITS
V
V
V
V
µA
µA
µA
nA
ms
µs
–15
140
0
200
110
0.15
0.05
0.05
0.05
0.4
0.3
0.3
0.3
V
V
V
V
V
V
OH
Output Voltage High,
RST
V
CC3
– 1
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3
LTC1727/LTC1728
elecTrical cHaracTerisTics
SYMBOL
V
RT3
V
RT18
V
RTA
V
CCOP
I
VCC3
I
VCC18
I
VCCA
t
RST
t
UV
V
OL
PARAMETER
Reset Threshold V
CC3
Reset Threshold V
CC18
Reset Threshold V
CCA
V
CC3
, V
CC18
Operating Voltage
V
CC3
Supply Current
V
CC18
Supply Current
V
CCA
Input Current
Reset Pulse Width
V
CC
Undervoltage Detect to
RST
Output Voltage Low,
RST
LTC1728-3.3 The
l
denotes specifications which apply over the full operating temperature range, otherwise specifications are at
T
A
= 25°C. V
CC3
= 3.3V, V
CC18
= 1.8V, V
CCA
= V
CC3
unless otherwise noted.
CONDITIONS
V
CC3
Input Threshold
V
CC18
Input Threshold
V
CCA
Input Threshold
RST
in Correct Logic State
V
CC18
> V
CC3
V
CC18
< V
CC3
, V
CC3
= 3.3V (Note 4)
V
CC18
< V
CC3
, V
CC18
= 1.8V (Note 4)
V
CCA
= 1V
RST
Low (Note 5)
V
CC18
, V
CC3
or V
CCA
Less Than Reset (Note 5)
Threshold V
RT
by More Than 1%
I
SINK
= 2.5mA, V
CC3
= 3.3V, V
CC18
= 0V
I
SINK
= 100µA, V
CC3
= 1V, V
CC18
= 0V
I
SINK
= 100µA, V
CC3
= 0V, V
CC18
= 1V
I
SINK
= 100µA, V
CC3
= 1V, V
CC18
= 1V
I
SOURCE
= 1µA (Note 6)
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MIN
3.036
1.656
0.985
1
TYP
3.086
1.683
1.000
1
10
1
MAX
3.135
1.710
1.015
7
2
20
2
15
280
UNITS
V
V
V
V
µA
µA
µA
nA
ms
µs
–15
140
0
200
110
0.15
0.05
0.05
0.05
0.4
0.3
0.3
0.3
V
V
V
V
V
V
OH
Output Voltage High,
RST
V
CC3
– 1
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
/V
CC25
/V
CC18
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
RTX
) until RST or COMPX passes through 1.5V.
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
OH
voltages greater than V
CC3
.
Note 7:
The V
CC5
reset override voltage is valid for an operating range less
than approximately 4.15V. Above this point the override is turned off and
the V
CC5
pin functions normally.
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4
LTC1727/LTC1728
Typical perForMance cHaracTerisTics
V
CCA
Input Current
vs Input Voltage
2.0
1.5
INPUT CURRENT (nA)
1.0
0.5
0
–0.5
–1.0
–1.5
–2.0
0.80 0.85 0.90 0.95 1 1.05 1.10 1.15 1.20
INPUT VOLTAGE (V)
1727/28 G01
V
CCA
Threshold Voltage
vs Temperature
1.015
V
CCA
THRESHOLD VOLTAGE, V
RTA
(V)
1.010
1.005
1.000
0.995
0.990
0.985
20 40 60
–60 –40 –20 0
TEMPERATURE (°C)
TYPICAL TRANSIENT DIRATION (µs)
450
400
350
300
250
200
150
100
50
Typical Transient Duration
vs Comparator Overdrive
T
A
= 25°C
RESET OCCURS
ABOVE CURVE
T
A
= 25°C
80
100
0
0.1
1
10
100
RESET COMPARATOR OVERDRIVE VOLTAGE (% OF V
CC
)
1727/28 G03
1727/28 G02
Reset Pulse Width
vs Temperature
280
RESET PULSE WIDTH, t
RST
(ms)
260
240
220
200
180
160
140
–60 –40 –20
0
20
40
60
80
100
I
SINK
(mA)
10
9
8
7
6
5
4
3
2
1
0
RST,
COMPX I
SINK
vs Supply Voltage
T
A
= 25°C
V
OL
= 0.4V
I
VCC25
(µA)
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0
1
3
4
2
V
CC3
OR V
CC5
(V)
5
6
I
VCC25
vs Temperature
(LTC1727-2.5/LT1728-2.5)
V
CC3
= 3.3V
V
CC25
= 2.5V
V
CCA
= 3.3V
V
OL
= 0.2V
TEMPERATURE (°C)
1727/28 G04
0.5
–60 –40 –20 0 20 40 60
TEMPERATURE (°C)
80
100
1727/28 G05
1727/28 G06
I
VCC3
vs Temperature (LTC1727-
2.5/LTC1728-2.5/LTC1728-3.3)
15
14
13
12
I
VCC3
(µA)
I
VCC3
(µA)
11
10
9
8
7
6
5
–60 –40 –20 0 20 40 60
TEMPERATURE (°C)
80
100
V
CC3
= 3.3V
V
CC25
= 2.5V
V
CCA
= 3.3V
1.5
1.4
1.3
1.2
I
VCC3
vs Temperature
(LTC1727-5/LTC1728-5)
V
CC5
= 5V
V
CC3
= 3.3V
V
CCA
= 3.3V
15
14
13
12
I
VCC5
(µA)
11
10
9
8
7
6
80
100
I
VCC5
vs Temperature
(LTC1727-5/LTC1728-5)
V
CC5
= 5V
V
CC3
= 3.3V
V
CCA
= 3.3V
1.1
1.0
0.9
0.8
0.7
0.6
0.5
–60 –40 –20 0 20 40 60
TEMPERATURE (°C)
5
–60 –40 –20 0 20 40 60
TEMPERATURE (°C)
80
100
1727/28 G07
1727/28 G08
1727/28 G09
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Embedded System
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