LTC1727/LTC1728

Micropower Precision

Triple Supply Monitors

in 8-Lead MSOP and

5-Lead SOT-23 Packages

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

1.5% Threshold Accuracy Over Temperature

Very Low Supply Current: 10

A Typ

200ms Reset Time Delay

Active Low RESET Output

Power Supply Glitch Immunity

Guaranteed RESET for V

CC3

or V

CC5

CC25

CC18

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

CC25

CC18

or V

CC3

down to 1V. The LTC1727/

LTC1728 may also be configured to monitor any one or
two V

inputs instead of three, depending on system

requirements.

Very low (10

A 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.

, LTC and LT are registered trademarks of Linear Technology Corporation.

Desktop Computers

Notebook Computers

Intelligent Instruments

Portable Battery-Powered Equipment

Network Servers

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

CC3

CC5

CCA

RST

GND

LTC1728-5

1727/28 TA01

3.3V

1.8V

0.1

R1
61.9k
1%

R2
100k
1%

DC/DC

CONVERTER

SYSTEM

LOGIC

0.1

LTC1727-2.5

1727/28 TA08

ADJUSTABLE

SUPPLY

3.3V

2.5V

R3
10k

POWER
GOOD

SYSTEM
RESET

R4
10k

CC3

CC25

CCA

GND

COMP3

COMP25

RST

COMPA

Triple Supply Monitor with Power Good Output

(3.3V, 2.5V and Adjustable)

LTC1727/LTC1728

BSOLUTE

CC3

, V

CC5

CC25

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

(Note 3) ............................................. 40

C to 85

Storage Temperature Range ................ 65

C to 150

Lead Temperature (Soldering, 10 sec)................ 300

PACKAGE/ORDER I FOR ATIO

ORDER

PART NUMBER

LTC1727EMS8-2.5
LTC1727EMS8-5

MS8

PART MARKING

Consult factory for Military grade parts.

JMAX

= 125

= 250

C/W

JMAX

= 125

= 200

C/W

(Notes 1, 2)

1
2
3
4

CC3

CC5

CC25

CCA

GND

8
7
6
5

COMP3
COMP25/COMP5
RST
COMPA

TOP VIEW

MS8 PACKAGE

8-LEAD PLASTIC MSOP

RST 1

GND 2

TOP VIEW

S5 PACKAGE

5-LEAD PLASTIC SOT-23

CCA

5 V

CC3

CC5

CC25

CC18

TOP VIEW

COMP3

RST

COMPA

CC3

CCA

GND

S8 PACKAGE

8-LEAD PLASTIC SO

COMP25/
COMP5

CC5

CC25

JMAX

= 125

= 150

C/W

ORDER

PART NUMBER

LTC1727ES8-2.5
LTC1727IS8-2.5
LTC1727ES8-5
LTC1727IS8-5

LTHY
LTHX

PART MARKING

172725
727I25
17275
1727I5

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

RT3

Reset Threshold V

CC3

Input Threshold

3.036

3.086

3.135

RT5

Reset Threshold V

CC5

Input Threshold (5V Version)

4.600

4.675

4.750

RT25

Reset Threshold V

CC25

Input Threshold (2.5V Version)

2.300

2.338

2.375

RTA

Reset Threshold V

CCA

Input Threshold

0.985

1.000

1.015

CCOP

CC3

, V

CC5

CC25

Operating Voltage

RST, COMP3, COMP5, COMP25 in Correct Logic State

CCOPA

CC3

, V

CC5

CC25

Operating Voltage

Minimum Supply Voltage to Guarantee COMPA

2.3

in Correct Logic State

VCC3

CC3

Supply Current

CC5

CC25

> V

CC3

CC5

CC25

< V

CC3

, V

CC3

= 3.3V (Note 4)

VCC25

CC25

Supply Current

CC25

< V

CC3

, V

CC25

= 2.5V (Note 4)

VCC5

CC5

Supply Current

CC5

= 5V, V

CC3

< V

CC5

VCCA

CCA

Input Current

CCA

= 1V

RST

Reset Pulse Width

RST Low with 10k Pull-Up to V

CC3

(Note 5)

140

200

280

All except LTC1728-1.8. The

denotes specifications which apply over the

full operating temperature range, otherwise specifications are at T

= 25

C. V

CC3

= 3.3V, V

CC5

= 5V, V

CC25

= 2.5V, V

CCA

= V

CC3

unless

otherwise noted.

ORDER

PART NUMBER

LTC1728ES5-1.8
LTC1728ES5-2.5
LTC1728ES5-5

PART MARKING

LTPH
LTIA
LTHZ

ELECTRICAL CHARACTERISTICS

LTC1727/LTC1728

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

typically 6

A. However, external pull-up resistors may be used when faster

rise times are required or for V

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.

Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.

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

but are not tested at these temperatures.

Note 4: Both V

CC3

and V

CC5

CC25

CC18

can act as the supply depending

on which pin has the greatest potential.

All except LTC1728-1.8. The

denotes specifications which apply over the

full operating temperature range, otherwise specifications are at T

= 25

C. V

CC3

= 3.3V, V

CC5

= 5V, V

CC25

= 2.5V, V

CCA

= V

CC3

unless

otherwise noted.

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Undervoltage Detect to RST

CC5

, V

CC25

, V

CC3

or V

CCA

Less Than Reset

110

or COMPX

Threshold V

by More Than 1% (Note 5)

Output Voltage Low, RST, COMPX

SINK

= 2.5mA, V

CC3

= 3V, V

CC5

CC25

= 0V

0.15

0.4

SINK

= 100

A, V

CC3

= 1V, V

CC5

CC25

= 0V

0.05

0.3

SINK

= 100

A, V

CC3

= 0V, V

CC5

CC25

= 1V

0.05

0.3

SINK

= 100

A, V

CC3

= 1V, V

CC5

CC25

= 1V

0.05

0.3

Output Voltage High, RST, COMPX (Note 6)

SOURCE

= 1

CC3

LTC1727-5/LTC1728-5 Only

OVR

CC5

Reset Override Voltage (Note 7)

Override V

CC5

Ability to Assert RST

CC3

0.025

ELECTRICAL CHARACTERISTICS

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

RT3

Reset Threshold V

CC3

Input Threshold

2.760

2.805

2.850

RT18

Reset Threshold V

CC18

Input Threshold

1.656

1.683

1.710

RTA

Reset Threshold V

CCA

Input Threshold

0.985

1.000

1.015

CCOP

CC3

, V

CC18

Operating Voltage

RST in Correct Logic State

VCC3

CC3

Supply Current

CC18

> V

CC3

CC18

< V

CC3

, V

CC3

= 3V (Note 4)

VCC18

CC18

Supply Current

CC18

< V

CC3

, V

CC18

= 1.8V (Note 4)

VCCA

CCA

Input Current

CCA

= 1V

RST

Reset Pulse Width

RST Low (Note 5)

140

200

280

Undervoltage Detect to RST

CC18

, V

CC3

or V

CCA

Less Than Reset (Note 5)

110

Threshold V

by More Than 1%

Output Voltage Low, RST

SINK

= 2.5mA, V

CC3

= 3V, V

CC18

= 0V

0.15

0.4

SINK

= 100

A, V

CC3

= 1V, V

CC18

= 0V

0.05

0.3

SINK

= 100

A, V

CC3

= 0V, V

CC18

= 1V

0.05

0.3

SINK

= 100

A, V

CC3

= 1V, V

CC18

= 1V

0.05

0.3

Output Voltage High, RST

SOURCE

= 1

A (Note 6)

CC3

LTC1728-1.8 The

denotes specifications which apply over the full operating temperature range, otherwise specifications are at

= 25

C. V

CC3

= 3V, V

CC18

= 1.8V, V

CCA

= V

CC3

unless otherwise noted.

LTC1727/LTC1728

TYPICAL PERFOR A CE CHARACTERISTICS

CCA

Threshold Voltage

vs Temperature

Reset Pulse Width
vs Temperature

Typical Transient Duration
vs Comparator Overdrive

CCA

Input Current

vs Input Voltage

INPUT VOLTAGE (V)

0.80 0.85

0.95

1.05

1.15

INPUT CURRENT (nA)

1.0

1.20

1727/28 G01

1.0

2.0

0.5

1.5

0.90

1.10

2.0

0.5

1.5

= 25

TEMPERATURE (

0.985

CCA

THRESHOLD VOLTAGE, V

RTA

(V)

0.990

0.995

1.000

1.005

100

1727/28 G02

1.010

1.015

RESET COMPARATOR OVERDRIVE VOLTAGE (% OF V

)

0.1

250

TYPICAL TRANSIENT DIRATION (

300

350

400

450

100

1727/28 G03

200

150

100

RESET OCCURS
ABOVE CURVE

= 25

VCC25

vs Temperature

(LTC1727-2.5/LT1728-2.5)

RST, COMPX I

SINK

vs Supply Voltage

TEMPERATURE (

60 40

RESET PULSE WIDTH, t

RST

(ms)

220

240

260

1727/28 G04

200

180

100

160

140

280

CC3

OR V

CC5

(V)

SINK

(mA)

1727/28 G05

= 0.4V

= 25

= 0.2V

TEMPERATURE (

0.5

VCC25

(

0.6

0.8

0.9

1.0

1.5

1.2

1727/28 G06

0.7

1.3

1.4

1.1

100

CC3

= 3.3V

CC25

= 2.5V

CCA

= 3.3V

VCC3

vs Temperature

(LTC1727-5/LTC1728-5)

VCC5

vs Temperature

(LTC1727-5/LTC1728-5)

VCC3

vs Temperature

(LTC1727-2.5/LT1728-2.5)

TEMPERATURE (

VCC3

(

1727/28 G07

100

CC3

= 3.3V

CC25

= 2.5V

CCA

= 3.3V

TEMPERATURE (

0.5

VCC3

(

0.6

0.8

0.9

1.0

1.5

1.2

1727/28 G08

0.7

1.3

1.4

1.1

100

CC5

= 5V

CC3

= 3.3V

CCA

= 3.3V

TEMPERATURE (

VCC5

(

1727/28 G09

100

CC5

= 5V

CC3

= 3.3V

CCA

= 3.3V

LTC1727/LTC1728

TYPICAL PERFOR A CE CHARACTERISTICS

CC25

Threshold Voltage

vs Temperature
(LTC1727-2.5/LTC1728-2.5)

TEMPERATURE (

CC25

THRESHOLD VOLTAGE, V

RT25

(V)

2.3750

2.3675

2.3600

2.3525

2.3450

2.3375

2.3300

2.3225

2.3150

2.3075

2.3000

1727/28 G10

100

CC5

Threshold Voltage

vs Temperature
(LTC1727-5/LTC1728-5)

CC3

Threshold Voltage

vs Temperature
(All But LTC1728-1.8)

TEMPERATURE (

CC3

THRESHOLD VOLTAGE, V

RT3

(V)

3.135

3.125

3.115

3.105

3.095

3.085

3.075

3.065

3.055

3.045

3.035

1727/28 G11

100

TEMPERATURE (

CC5

THESHOLD VOLTAGE, V

RT5

(V)

4.675

4.700

4.750

4.725

100

1727/28 G12

4.650

4.625

4.600

40 20

TEMPERATURE (

0.5

VCC18

(

0.6

0.8

0.9

1.0

1.5

1.2

1727/28 G13

0.7

1.3

1.4

1.1

100

CC3

= 3V

CC18

= 1.8V

CCA

= 3V

CC3

Threshold Voltage

vs Temperature (LTC1728-1.8)

CC18

Threshold Voltage

vs Temperature (LTC1728-1.8)

VCC3

vs Temperature

(LTC1728-1.8)

VCC18

vs Temperature

(LTC1728-1.8)

TEMPERATURE (

VCC3

(

1727/28 G14

100

CC3

= 3V

CC18

= 1.8V

CCA

= 3V

TEMPERATURE (

1.650

CC18

THRESHOLD VOLTAGE, V

RT18

(V)

1.660

1.670

1.680

1.690

100

1727/28 G15

1.700

1.710

TEMPERATURE (

CC3

THRESHOLD VOLTAGE, V

RT3

(V)

2.845

2.835

2.825

2.815

2.805

2.795

2.785

2.775

2.765

1727/28 G16

100

LTC1727/LTC1728

(LTC1727/LTC1728)

PI FU CTIO S

CC3

(Pin 1/Pin 5): 3.3V Sense Input and Power

Supply Pin. (3V Sense Input and Power Supply Pin for
LTC1728-1.8.) This pin provides power to the part
when the voltage on V

CC3

is greater than the voltage on

CC5

CC25

CC18

. Bypass to ground with a

0.1

ceramic capacitor.

CC5

(Pin 2/Pin 4): 5V Sense Input and Power Supply

Pin. This pin is used on the LTC1727-5/LTC1728-5 to
provide power to the part when the voltage on V

CC5

greater than the voltage on V

CC3

. Bypass to ground with

0.1

F ceramic capacitor.

CC25

(Pin 2/Pin 4): 2.5V Sense Input and Power Supply

Pin. This pin is used on the LTC1727-2.5/LTC1728-2.5 to
provide power to the part when the voltage on V

CC25

greater than the voltage on V

CC3

. Bypass to ground with

0.1

F ceramic capacitor.

CC18

(Pin 2/Pin 4): 1.8V Sense Input and Power Supply

Pin. This pin is used on the LTC1728-1.8 to provide
power to the part when the voltage on V

CC18

is greater

than the voltage on V

CC3

. Bypass to ground with a

0.1

ceramic capacitor.

CCA

(Pin 3/Pin 3): 1V Sense, High Impedance Input. If

unused, it can be tied to either V

CC3

or V

CC5

CC25

CC18

GND (Pin 4/Pin 2): Ground.

COMPA (Pin 5): V

CCA

Comparator Output for the LTC1727.

Active high, open-drain logic output with weak pull-up to
V

CC3

. Asserted when V

CCA

is above V

RTA

. Deasserted

when V

CCA

is below V

RTA

or if both the V

CC3

and V

CC5

supply pins are too low to power the internal bandgap
reference (typically < 2.0V). Can be pulled greater than
V

CC3

using an external pull-up.

RST (Pin 6/Pin 1): Reset Logic Output. Active low, open-
drain logic output with weak pull-up to V

CC3

. Can be pulled

up greater than V

CC3

when interfacing to 5V logic. As-

serted when one or all of the supplies are below trip thresh-
olds and held for 200ms after all supplies become valid.

COMP5 (Pin 7): V

CC5

Comparator Output for the

LTC1727-5. Active high, open-drain logic output with
weak pull-up to V

CC3

. Asserted when V

CC5

is above V

RT5

Can be pulled greater than V

CC3

using an external pull-up.

COMP25 (Pin 7): V

CC25

Comparator Output for the

LTC1727-2.5. Active high, open-drain logic output with
weak pull-up to V

CC3

. Asserted when V

CC25

is above

RT25

. Can be pulled greater than V

CC3

using an external

pull-up.

COMP3 (Pin 8): V

CC3

Comparator Output for the LTC1727.

Active high, open-drain logic output with weak pull-up to
V

CC3

. Asserted when V

CC3

is above V

RT3

. Can be pulled

greater than V

CC3

using an external pull-up.

LTC1727/LTC1728

Power-Down

On power-down, once any of the V

inputs drop below

its threshold, RST is held at a logic low. A logic low of 0.3V
is guaranteed until both V

CC3

and V

CC5

CC25

CC18

drop

below 1V.

Glitch Immunity

The RST output of the LTC1727/LTC1728 have two forms
of glitch immunity built in. First, the input monitors require
the input voltage to transition at least 10% of the input
threshold (0.1 · V

RTH

) below the input threshold for

approximately 50

s in order to force the monitor output

low. The duration of the transition must be longer for
voltage transitions of lesser magnitude (see Figure 1).
Secondly, the reset pulse width of approximately 200ms
acts to debounce the RST output ensuring that the RST
output will always be in the correct state.

The individual monitor outputs of the LTC1727 do not
have hysteresis and will track the monitor inputs relative
to the monitor's input threshold (V

RTA

, V

RT25

, V

RT3

and

RT5

). A very slow moving input voltage with ripple riding

on it may cause the individual monitor outputs (COMPA,
COMP25, COMP3 and COMP5) to toggle on the ripple as
the input voltage passes the input threshold. The slow
response time of the LTC1727's input monitors has a
tendency to integrate signals on the inputs improving their
immunity to noise and ripple.

APPLICATIO S I FOR ATIO

Supply Monitoring

The LTC1727 is a low power, high accuracy triple supply
monitoring circuit with three monitor outputs and a
200ms microprocessor reset output.

The LTC1728 is a low power, high accuracy triple supply
monitoring circuit with a single 200ms microprocessor
reset output.

All three V

inputs must be above predetermined thresh-

olds for reset not to be invoked. The LTC1727/LTC1728
will assert reset during power-up, power-down and brown-
out conditions on any one or all of the V

inputs.

Power Detect

The LTC1727/LTC1728 are powered from the 3.3V/3V
input pin (V

CC3

), the 1.8V input pin (V

CC18

), the 2.5V

input pin (V

CC25

) or the 5V input pin (V

CC5

), whichever

pin has the highest potential. This ensures the part pulls
the RST pin low as soon as either input pin is

1V.

Power-Up

Upon power-up, either the V

CC5

CC25

CC18

or V

CC3

pin,

can power the part. This ensures that RST will be low when
either V

CC5

CC25

CC18

or V

CC3

reaches 1V. As long as

any one of the V

inputs is below its predetermined

threshold, RST will stay a logic low. Once all of the V

inputs rise above their thresholds, an internal timer is
started and RST is released after 200ms.

RST is reasserted whenever any one of the V

inputs

drops below its predetermined threshold and remains
asserted until 200ms after all of the V

inputs are above

their thresholds.

On the LTC1727, each of the comparator outputs will be
low until the V

input that is monitored by that compara-

tor rises above the appropriate predetermined threshold.
The COMP3, and COMP5/COMP25 outputs are guaran-
teed to be in the correct logic state for either V

CC3

CC5

CC25

greater than 1V. The COMPA output requires

the internal bandgap reference to be valid before the
correct logic state can be output. Therefore, the COMPA
output will be held low until V

CCA

is above 1V and V

CC3

CC5

CC25

is greater than 2V (typ).

RESET MONITOR OVERDRIVE VOLTAGE (% OF V

)

0.1

250

TRANSIENT DURATION (

300

350

400

450

100

1727/28 F01

200

150

100

Figure 1. Transient Duration vs Comparator Overdrive

LTC1727/LTC1728

Override Functions (5V Versions Only)

The V

CCA

pin, if unused, can be tied to either V

CC3

or V

CC5

This is an obvious solution since the trip points for V

CC3

and V

CC5

will always be greater than the trip point for V

CCA

The V

CC5

input trip point is disabled if its voltage is equal

to the voltage on V

CC3

25mV and the voltage on V

CC5

less than 4.15V. In this manner, the LTC1727-5/
LTC1728-5 will behave as a 3.3V monitor and V

CC5

reset

capability will be disabled.

The V

CC5

trip point is reenabled when the voltage on V

CC5

is equal to the voltage on V

CC3

25mV and the two inputs

are greater than approximately 4.15V. In this manner, the
part can function as a 5V monitor with the 3.3V monitor
disabled.

APPLICATIO S I FOR ATIO

Figure 3. RST Voltage vs Supply Voltage

Figure 2. Single Supply Monitor with Others Disabled

When monitoring either 3.3V or 5V with V

CC3

strapped to

CC5

(see Figure 2), the part determines which is the

appropriate range. The part handles this situation as
shown in Figure 3. Above 1V and below V

RT3

, RST is held

low. From V

RT3

to approximately 4.15V the part assumes

3.3V supply monitoring and RST is deasserted. Above
approximately 4.15V the part operates as a 5V monitor.
In most systems the 5V supply will pass through the 3.1V
to 4.15V region in < 200ms during power-up, and the
RST output will behave as desired. Table 1 summarizes
the state of RST at various operating voltages with
V

CC3

= V

CC5

Table 1. Override Truth Table (V

CC3

= V

CC5

)

INPUTS (V

CC3

= V

CC5

= V

)

RST

RT3

4.15V

RT5

CC3

CC5

CCA

GND

RST

LTC1728-5

1727/28 F02

TO SYSTEM
RESET

R1
10k

3.3V OR 5V

SUPPLY VOLTAGE (V)

RST OUTPUT VOLTAGE (V)

1727/28 F03

CC3

= V

CC5

= V

CCA

= 0V TO 5V

10k PULL-UP FROM RST TO V

CC3

LTC1727/LTC1728

APPLICATIO S I FOR ATIO

Figure 5. RST Output Voltage
Characteristics of the Circuit in Figure 4

CC5

(V)

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

RST OUTPUT VOLTAGE (V)

1727/28 F05

CC5

= V

CCA

= 0V TO 5V

10k PULL-UP FROM RST TO V

CC5

= 25

Figure 4 contains a simple circuit for 5V systems that can't
risk the RST output going high in the 3.1V to 4.15V range
(possibly due to very slow rise time on the 5V supply).
Diode D1 powers the LTC1728-5 while dropping

0.6V

from the V

CC5

pin to the V

CC3

pin. This prevents the part's

internal override circuit from being activated. Without the
override circuit active, the RST pin stays low until V

CC5

reaches V

RT5

4.675V. (See Figure 5.)

Figure 4. LTC1728-5 Monitoring a Single 5V
Supply. D1 Used to Avoid RST High Near 3.1V
to 4V (See Figure 3).

CC3

CC5

CCA

GND

RST

LTC1728-5

1727/28 F04

TO SYSTEM
RESET

R1
10k

0.1

D1: MMBD914 OR EQUIVALENT

LTC1727-2.5/LTC1728-2.5/LTC1728-1.8
Override Functions

The V

CCA

pin, if unused, can be tied to either V

CC3

or V

CC25

CC18

. This is an obvious solution since the trip points for

CC3

and V

CC25

CC18

will always be greater than the trip

point for V

CCA

. Likewise, the V

CC25

CC18

, if unused, can

be tied to V

CC3

. V

CC3

must always be used. Tying V

CC3

CC25

CC18

and operating off of a 2.5V/1.8V supply will

result in the continuous assertion of RST.

LTC1727/LTC1728

TYPICAL APPLICATIO S

Triple Supply Monitor (3.3V, 5V and Adjustable)

CC3

CC5

CCA

GND

RST

LTC1728-5

3.3V

SYSTEM RESET

*TO PRESERVE THRESHOLD ACCURACY, SET PARALLEL
COMBINATION OF R1 AND R2

66.5k

R2*

R1*

1727/28 TA03

ADJUSTABLE SUPPLY

OR DC/DC FEEDBACK

DIVIDER

Dual Supply Monitor (3.3V and 5V, Defeat V

CCA

Input)

CC3

CC5

CCA

GND

RST

LTC1728-5

3.3V

SYSTEM RESET

1727/28 TA04

Dual Supply Monitor (3.3V or 5V Plus Adjustable)

CC3

CC5

CCA

GND

RST

LTC1728-5

R2*

1727/28 TA05

R1*

ADJUSTABLE

SUPPLY

3.3V OR

10k

SYSTEM RESET

*TO PRESERVE THRESHOLD ACCURACY, SET PARALLEL
COMBINATION OF R1 AND R2

66.5k

REFER TO LTC1728-5 OVERRIDE FUNCTIONS IN
THE APPLICATIONS INFORMATION SECTION

LTC1727/LTC1728

S5 Package

5-Lead Plastic SOT-23

(LTC DWG # 05-08-1633)

PACKAGE DESCRIPTIO

Dimensions in inches (millimeters) unless otherwise noted.

0.95

(0.037)

REF

1.50 1.75

(0.059 0.069)

0.35 0.55

(0.014 0.022)

0.35 0.50

(0.014 0.020)

FIVE PLACES (NOTE 2)

S5 SOT-23 0599

2.80 3.00

(0.110 0.118)

(NOTE 3)

1.90

(0.074)

REF

0.90 1.45

(0.035 0.057)

0.90 1.30

(0.035 0.051)

0.00 0.15

(0.00 0.006)

0.09 0.20

(0.004 0.008)

(NOTE 2)

2.60 3.00

(0.102 0.118)

NOTE:
1. DIMENSIONS ARE IN MILLIMETERS
2. DIMENSIONS ARE INCLUSIVE OF PLATING
3. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
4. MOLD FLASH SHALL NOT EXCEED 0.254mm
5. PACKAGE EIAJ REFERENCE IS SC-74A (EIAJ)

MS8 Package

8-Lead Plastic MSOP

(LTC DWG # 05-08-1660)

MSOP (MS8) 1098

* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH,

PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE

** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.

INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE

0.021

0.006

(0.53

0.015)

TYP

SEATING

PLANE

0.007

(0.18)

0.040

0.006

(1.02

0.15)

0.012

(0.30)

REF

0.006

0.004

(0.15

0.102)

0.034

0.004

(0.86

0.102)

0.0256

(0.65)

BSC

0.193

0.006

(4.90

0.15)

7 6

0.118

0.004*

(3.00

0.102)

0.118

0.004**

(3.00

0.102)

LTC1727/LTC1728

PACKAGE DESCRIPTIO

Dimensions in inches (millimeters) unless otherwise noted.

S8 Package

8-Lead Plastic Small Outline (Narrow 0.150)

(LTC DWG # 05-08-1610)

0.016 0.050

(0.406 1.270)

0.010 0.020

(0.254 0.508)

TYP

0.008 0.010

(0.203 0.254)

SO8 1298

0.053 0.069

(1.346 1.752)

0.014 0.019

(0.355 0.483)

TYP

0.004 0.010

(0.101 0.254)

0.050

(1.270)

BSC

0.150 0.157**

(3.810 3.988)

0.189 0.197*

(4.801 5.004)

0.228 0.244

(5.791 6.197)

DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE

DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

LTC1727/LTC1728

LINEAR TECHNOLOGY CORPORATION 1999

17278f LT/TP 0400 4K · PRINTED IN THE USA

PART NUMBER

DESCRIPTION

COMMENTS

LTC690

5V Supply Monitor, Watchdog Timer and Battery Backup

4.65V Threshold

LTC694-3.3

3.3V Supply Monitor, Watchdog Timer and Battery Backup

2.9V Threshold

LTC699

5V Supply Monitor and Watchdog Timer

4.65V Threshold

LTC1232

5V Supply Monitor, Watchdog Timer and Push-Button Reset

4.37V/4.62V Threshold

LTC1326

Micropower Precision Triple Supply Monitor for 5V, 3.3V and ADJ

4.725V, 3.118V, 1V Thresholds (

0.75%)

LTC1326-2.5

Micropower Precision Triple Supply Monitor for 2.5V, 3.3V and ADJ

2.363V, 3.118V, 1V Thresholds (

0.75%)

LTC1443/LTC1444

Micropower Quad Comparators with 1% Reference

LTC1443 Has 1.182V Reference, LTC1444/LTC1445

LTC1445

Have 1.221V Reference and Adjustable Hysteresis

LTC1536

Precision Triple Supply Monitor for PCI Applications

Meets PCI t

FAIL

Timing Specifications

LTC1540

Nanopower Comparator with 2% Reference

1.182V Reference, 300nA Supply Current, 8-Pin MSOP

LTC1726-2.5

Micropower Triple Supply Monitor for 2.5V, 3.3V and ADJ

Adjustable RESET and Watchdog Time Outs

LTC1726-5

Micropower Triple Supply Monitor for 5V, 3.3V and ADJ

Adjustable RESET and Watchdog Time Outs

LTC1985-1.8

Micropower Triple Supply Monitor for 3.3V, 1.8V and ADJ

Push-Pull RESET Output, SOT-23

RELATED PARTS

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900

FAX: (408) 434-0507

www.linear-tech.com

TYPICAL APPLICATIO

Triple Supply Monitor with Manual Reset Button

CC3

CC5

CCA

RST

GND

LTC1728-5

1727/28 TA02

100nF

3.3V

12V (

5%)

TRIP

= 11.2V

(

0.17V)

R2
105k
0.1%

*OPTIONAL RESISTOR RECOMMENDED
TO EXTEND ESD TOLERANCE

R3*

10k

MANUAL

RESET BUTTON

(NORMALLY OPEN)

R1
1.07M
0.1%

100nF

TRIP

(R1 + R2)

R1 = R2

CCA

( )

TRIP

CCA

Ð­Ð»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: LTC1727IS8-2.5

ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: LTC1727IS8-2.5