LTC1727/LTC1728
Micropower Precision
Triple Supply Monitors
in 8-Lead MSOP and
5-Lead SOT-23 Packages
FEATURES
■
DESCRIPTIO
■
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■
■
■
■
■
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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
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
package and the LTC1728 is available in a 5-lead SOT-23
package.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
APPLICATIO S
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Desktop Computers
Notebook Computers
Intelligent Instruments
Portable Battery-Powered Equipment
Network Servers
TYPICAL APPLICATIO
DC/DC
CONVERTER
3.3V
5V
1.8V
SYSTEM
LOGIC
Triple Supply Monitor with Power Good Output
(3.3V, 2.5V and Adjustable)
LTC1727-2.5
3.3V
2.5V
1
2
3
R2
4
V
CC3
COMP3
8
7
6
5
1727/28 TA08
5
V
CC3
RST
1
LTC1728-5
0.1µF
0.1µF
4
V
CC5
R1
61.9k
1% 3
V
CCA
R2
100k
1%
GND
1727/28 TA01
2
ADJUSTABLE
SUPPLY
R1
U
R3
10k
R4
10k
POWER
GOOD
SYSTEM
RESET
V
CC25
COMP25
V
CCA
GND
RST
COMPA
17278fb
U
U
1
LTC1727/LTC1728
ABSOLUTE
AXI U
RATI GS
(Notes 1, 2)
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
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
PACKAGE/ORDER I FOR ATIO
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
MS8 PACKAGE
8-LEAD PLASTIC MSOP
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 200°C/W
T
JMAX
= 125°C,
θ
JA
= 150°C/W
ORDER
PART NUMBER
LTC1727EMS8-2.5
LTC1727EMS8-5
MS8
PART MARKING
LTHY
LTHX
ORDER
PART NUMBER
LTC1727ES8-2.5
LTC1727IS8-2.5
LTC1727ES8-5
LTC1727IS8-5
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.
ELECTRICAL CHARACTERISTICS
SYMBOL
V
RT3
V
RT5
V
RT25
V
RTA
V
CCOP
V
CCOPA
PARAMETER
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
All except LTC1728-1.8/LTC1728-3.3. The
●
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
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
●
●
●
●
●
●
2
U
U
W
W W
U
W
TOP VIEW
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
S5 PACKAGE
5-LEAD PLASTIC SOT-23
T
JMAX
= 125°C,
θ
JA
= 250°C/W
S8
PART MARKING
172725
727I25
17275
1727I5
ORDER
PART NUMBER
LTC1728ES5-1.8
LTC1728ES5-2.5
LTC1728ES5-3.3
LTC1728ES5-5
LTC1728HS5-5
S5
PART MARKING
LTPH
LTIA
LTYP
LTHZ
LTHZ
MIN
3.036
4.600
2.300
0.985
1
TYP
3.086
4.675
2.338
1.000
2
MAX
3.135
4.750
2.375
1.015
7
2.3
UNITS
V
V
V
V
V
V
17278fb
LTC1727/LTC1728
ELECTRICAL CHARACTERISTICS
SYMBOL
I
VCC3
I
VCC25
I
VCC5
µA
I
VCCA
t
RST
t
UV
V
OL
PARAMETER
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
●
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
I
SOURCE
= 1µA
Override V
CC5
Ability to Assert RST
●
●
●
●
●
V
CC3
– 1
●
●
●
●
●
●
●
●
MIN
TYP
1
10
1
MAX
2
20
2
10
UNITS
µA
µA
µA
20
nA
nA
ms
ms
µs
– 15
–50
140
140
0
0
200
110
0.15
0.05
0.05
0.05
15
50
280
350
0.4
0.3
0.3
0.3
V
V
V
V
V
V
OH
V
OVR
Output Voltage High, RST, COMPX (Note 6)
V
CC5
Reset Override Voltage (Note 7)
LTC1727-5/LTC1728-5 Only
V
CC3
±0.025
V
LTC1728-1.8 The
●
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)
●
●
●
●
●
V
CC3
– 1
●
●
●
●
●
●
●
●
●
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
17278fb
3
LTC1727/LTC1728
ELECTRICAL CHARACTERISTICS
LTC1728-3.3 The
●
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.
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
= 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)
●
●
●
●
●
●
●
●
●
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
●
●
●
●
●
V
CC3
– 1
0.15
0.05
0.05
0.05
0.4
0.3
0.3
0.3
V
OH
Output Voltage High, RST
V
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
/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 PERFOR A CE CHARACTERISTICS
V
CCA
Input Current
vs Input Voltage
2.0
1.5
V
CCA
THRESHOLD VOLTAGE, V
RTA
(V)
T
A
= 25°C
1.010
1.005
1.000
0.995
0.990
0.985
–60 –40 –20 0
20 40 60
TEMPERATURE (°C)
TYPICAL TRANSIENT DIRATION (µs)
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
Reset Pulse Width
vs Temperature
280
10
9
8
RESET PULSE WIDTH, t
RST
(ms)
260
240
220
200
180
160
140
–60 –40 –20
I
VCC25
(µA)
I
SINK
(mA)
0
20
40
60
TEMPERATURE (°C)
1727/28 G04
I
VCC3
vs Temperature (LTC1727-2.5/
LTC1728-2.5/LTC1728-3.3)
15
14
13
12
V
CC3
= 3.3V
V
CC25
= 2.5V
V
CCA
= 3.3V
1.5
1.4
1.3
1.2
I
VCC3
(µA)
I
VCC3
(µA)
I
VCC5
(µA)
11
10
9
8
7
6
5
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
U W
80
1727/28 G07
V
CCA
Threshold Voltage
vs Temperature
1.015
Typical Transient Duration
vs Comparator Overdrive
450
400
350
300
250
200
150
100
50
0
0.1
1
10
100
RESET COMPARATOR OVERDRIVE VOLTAGE (% OF V
CC
)
1727/28 G03
T
A
= 25°C
RESET OCCURS
ABOVE CURVE
80
100
1727/28 G02
RST, COMPX I
SINK
vs Supply Voltage
T
A
= 25°C
I
VCC25
vs Temperature
(LTC1727-2.5/LT1728-2.5)
1.5
1.4
V
OL
= 0.4V
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
V
CC3
= 3.3V
V
CC25
= 2.5V
V
CCA
= 3.3V
7
6
5
4
3
2
1
0
V
OL
= 0.2V
100
0
1
3
4
2
V
CC3
OR V
CC5
(V)
5
6
0.5
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
1727/28 G05
1727/28 G06
I
VCC3
vs Temperature
(LTC1727-5/LTC1728-5)
15
V
CC5
= 5V
V
CC3
= 3.3V
V
CCA
= 3.3V
I
VCC5
vs Temperature
(LTC1727-5/LTC1728-5)
14
13
12
11
10
9
8
7
6
80
100
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 G08
1727/28 G09
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5
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