LTC1727_15_技术文档

LTC1727/LTC1728

Micropower Precision

Triple Supply Monitors

in 8-Lead MSOP and

5-Lead SOT-23 Packages

FeaTures

DescripTion

The LTC^®1727 is a triple supply monitor intended for

systemswithmultiplesupplyvoltages. Eachsupplymoni-

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.

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

±±.5ꢀ Threshold Aꢁꢁuraꢁy Oꢂer Temperature

n

Very Low Supply Current: ±0µA Typ

The LTC1728 is functionally identical to the LTC1727

without the individual monitor outputs.

n

200ms Reset Time Delay

Active Low RESET Output

n

The RST output is guaranteed to be in the correct state

Power Supply Glitch Immunity

for V /V

/V

or V

down to 1V. The LTC1727/

Guaranteed RESET for V

≥ 1V

CC5 CC25 CC18

CC3

≥ 1V

LTC1728 may also be conﬁgured to monitor any one or

or V /V

/V

CC5 CC25 CC18

n

two V inputs instead of three, depending on system

LTC±727 Inꢁludes Monitor Output for Eaꢁh Supply

LTC±727: 8-Lead MSOP and SO Paꢁkages

LTC±728: 5-Lead SOT-23 Paꢁkage

CC

requirements.

Verylow(10µAtypical)supplycurrentmakestheLTC1727/

LTC1728 ideal for power conscious systems.

applicaTions

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.

n

Desktop Computers

n

Notebook Computers

n

Intelligent Instruments

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

All other trademarks are the property of their respective owners.

n

Portable Battery-Powered Equipment

n

Network Servers

Typical applicaTion

3.3V

5V

1.8V

Triple Supply Monitor with Power Good Output

(3.3V, 2.5V and Adjustable)

DC/DC

CONVERTER

SYSTEM

LOGIC

R3

R4

LTC1727-2.5

5

4

3

1

10k 10k

1

2

3

4

8

7

6

5

V

RST

CC3

POWER

GOOD

3.3V

2.5V

V

COMP3

COMP25

RST

CC3

LTC1728-5

CC25

CCA

CC5

CCA

R1

61.9k

1%

R1

ADJUSTABLE

SUPPLY

SYSTEM

RESET

0.1µF

2

0.1µF

GND

R2

GND COMPA

1727/28 TA08

1727/28 TA01

100k

1%

17278fb

1

LTC1727/LTC1728

(Notes ±. 2)

absoluTe MaxiMuM raTings

V

, V /V

/V

, V

–0.3V to 7V

Operating Temperature Range

CC3 CC5 CC25 CC18 CCA ........................

RST............................................................. –0.3V to 7V

COMPA, COMP3, COMP25/COMP5

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

(MS8 and SO-8 Only) ............................. –0.3V to 7V

pin conFiguraTion

TOP VIEW

V

1

2

3

4

8

7

6

5

COMP3

COMP25/

COMP5

CC3

/

V

1

2

3

4

8 COMP3

7 COMP25/COMP5

6 RST

RST 1

5 V

CC3

V

CC25

CC3

CC5

V

/V

V

CC5 CC25

GND 2

V

GND

V

4 V

V

/

CCA

CC5

CC25

CC18

V

RST

CCA

5 COMPA

V

3

/

CCA

GND

COMPA

MS8 PACKAGE

8-LEAD PLASTIC MSOP

S5 PACKAGE

5-LEAD PLASTIC SOT-23

= 125°C, θ = 250°C/W

S8 PACKAGE

8-LEAD PLASTIC SO

T

= 125°C, θ = 200°C/W

JMAX

JA

T

JMAX

JA

T

JMAX

= 125°C, θ = 150°C/W

JA

ORDER

MS8

ORDER

S8

ORDER

S5

PART NUMBER PART MARKING PART NUMBER PART MARKING PART NUMBER

PART MARKING

LTC1727EMS8-2.5

LTC1727EMS8-5

LTHY

LTHX

LTC1727ES8-2.5

LTC1727IS8-2.5

LTC1727ES8-5

LTC1727IS8-5

172725

727I25

17275

LTC1728ES5-1.8

LTC1728ES5-2.5

LTC1728ES5-3.3

LTC1728ES5-5

LTC1728HS5-5

LTPH

LTIA

LTYP

LTHZ

172715

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 ^{All exꢁept LTC±728-±.8/LTC±728-3.3. The}l denotes speꢁiﬁꢁations whiꢁh

apply oꢂer the full operating temperature range, otherwise speꢁiﬁꢁations are at T_A= 25°C. V_CC3= 3.3V, V_CC5= 5V,

V_CC25= 2.5V, V_CCA= V_CC3unless otherwise noted.

SYMBOL PARAMETER

CONDITIONS

MIN

3.036

4.600

2.300

0.985

1

TYP

MAX UNITS

l

V

Reset Threshold V

V

Input Threshold

3.086

4.675

2.338

1.000

3.135

4.750

2.375

1.015

7

V

RT3

CC3

Input Threshold (5V Version)

RT5

CC5

Input Threshold (2.5V Version)

RT25

RTA

CC25

Input Threshold

CCA

V

, V /V Operating Voltage

CC3 CC5 CC25

RST, COMP3, COMP5, COMP25 in Correct Logic State

CCOP

CCOPA

, V /V

CC3 CC5 CC25

Operating Voltage

Minimum Supply Voltage to Guarantee COMPA

in Correct Logic State

2

2.3

17278fb

2

LTC1727/LTC1728

elecTrical cHaracTerisTics ^{All exꢁept LTC±728-±.8/LTC±728-3.3. The}l denotes speꢁiﬁꢁations whiꢁh

apply oꢂer the full operating temperature range, otherwise speꢁiﬁꢁations are at T_A= 25°C. V_CC3= 3.3V, V_CC5= 5V,

V_CC25= 2.5V, V_CCA= V_CC3unless otherwise noted.

SYMBOL PARAMETER

CONDITIONS

MIN

TYP

MAX UNITS

l

I

V

Supply Current

V

/V

> V

CC3

1

10

2

20

µA

VCC3

CC3

CC5 CC25

/V

< V , V

= 3.3V (Note 4)

CC5 CC25

CC3 CC3

l

I

V

Supply Current

V

< V , V = 2.5V (Note 4)

CC3 CC25

1

2

µA

VCC25

VCC5

VCCA

CC25

Supply Current

Input Current

= 5V, V

< V

CC5

10

20

CC5

CCA

CC5

CC3

l

= 1V

–15

–20

0

15

50

nA

CCA

–40°C < T < 125°C

A

l

t

Reset Pulse Width

RST Low with 10k Pull-Up to V (Note 5)

140

200

280

350

ms

RST

CC3

–40°C < T < 125°C

A

V

Undervoltage Detect to RST

V

, V

or V Less Than Reset

CCA

110

µs

UV

CC

CC5 CC25 CC3

or COMPX

Threshold V by More Than 1% (Note 5)

RT

l

V

Output Voltage Low, RST, COMPX

I

= 2.5mA, V

= 100µA, V

= 3V, V /V

CC5 CC25

= 0V

= 1V

0.15

0.05

0.4

0.3

V

OL

OH

SINK

CC3

= 1V, V /V

CC5 CC25

= 0V, V /V

CC5 CC25

= 1V, V /V

CC5 CC25

l

V

Output Voltage High, RST, COMPX (Note 6)

I

= 1µA

V

– 1

CC3

V

SOURCE

LTC1727-5/LTC1728-5 Only

Reset Override Voltage (Note 7)

V

Override V

Ability to Assert RST

V

0.025

CC3

V

OVR

CC5

LTC±728-±.8 The l denotes speꢁiﬁꢁations whiꢁh apply oꢂer the full operating temperature range, otherwise speꢁiﬁꢁations are at

T_A= 25°C. V_CC3= 3V, V_CC±8= ±.8V, V_CCA= V_CC3unless otherwise noted.

SYMBOL

PARAMETER

CONDITIONS

MIN

2.760

1.656

0.985

1

TYP

MAX

2.850

1.710

1.015

7

UNITS

l

V

Reset Threshold V

V

Input Threshold

2.805

1.683

1.000

V

RT3

RT18

RTA

CC3

Input Threshold

CC18

CCA

CC18

Input Threshold

CCA

V

, V Operating Voltage

CC3 CC18

RST in Correct Logic State

CCOP

VCC3

l

I

Supply Current

V

> V

CC3

1

10

2

20

µA

CC3

CC18

< V , V

= 3V (Note 4)

CC3 CC3

l

I

t

V

Supply Current

V

< V , V = 1.8V (Note 4)

CC3 CC18

1

2

µA

nA

ms

µs

VCC18

VCCA

RST

CC18

Input Current

= 1V

CCA

–15

140

0

15

CCA

Reset Pulse Width

Undervoltage Detect to RST

RST Low (Note 5)

, V or V Less Than Reset (Note 5)

CCA

200

110

280

V

UV

CC

CC18 CC3

Threshold V by More Than 1%

RT

l

V

Output Voltage Low, RST

I

= 2.5mA, V

= 100µA, V

= 3V, V

= 1V, V

= 0V, V

= 1V, V

= 0V

= 1V

0.15

0.05

0.4

0.3

V

OL

OH

SINK

CC3

CC18

l

V

Output Voltage High, RST

I

= 1µA (Note 6)

V

– 1

CC3

V

SOURCE

17278fb

3

LTC1727/LTC1728

elecTrical cHaracTerisTics

LTC±728-3.3 The l denotes speꢁiﬁꢁations whiꢁh apply oꢂer the full operating temperature range, otherwise speꢁiﬁꢁations are at

T_A= 25°C. V_CC3= 3.3V, V_CC±8= ±.8V, V_CCA= V_CC3unless otherwise noted.

SYMBOL

PARAMETER

CONDITIONS

MIN

3.036

1.656

0.985

1

TYP

MAX

3.135

1.710

1.015

7

UNITS

l

V

Reset Threshold V

V

Input Threshold

3.086

1.683

1.000

V

RT3

RT18

RTA

CC3

Input Threshold

CC18

CCA

CC18

Input Threshold

CCA

V

, V Operating Voltage

CC3 CC18

RST in Correct Logic State

CCOP

VCC3

l

I

Supply Current

V

> V

CC3

1

10

2

20

µA

CC3

CC18

< V , V

= 3.3V (Note 4)

< V , V = 1.8V (Note 4)

CC3 CC18

CC3 CC3

l

I

t

V

Supply Current

V

1

2

µA

nA

ms

µs

VCC18

VCCA

RST

CC18

Input Current

= 1V

CCA

–15

140

0

15

CCA

Reset Pulse Width

Undervoltage Detect to RST

RST Low (Note 5)

, V or V Less Than Reset (Note 5)

CCA

200

110

280

V

UV

CC

CC18 CC3

Threshold V by More Than 1%

RT

l

V

Output Voltage Low, RST

I

= 2.5mA, V

= 100µA, V

= 3.3V, V = 0V

CC18

0.15

0.05

0.4

0.3

V

OL

SINK

CC3

= 1V, V

= 0V, V

= 1V, V

= 0V

CC18

= 1V

l

V

Output Voltage High, RST

I

= 1µA (Note 6)

V

CC3

– 1

V

OH

SOURCE

Note ±: 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 4: Both V

on which pin has the greatest potential.

Note 5: Measured from when input passes through the input threshold

and V /V

/V

can act as the supply depending

CC3

CC5 CC25 CC18

(V ) until RST or COMPX passes through 1.5V.

RTX

Note 2: All voltage values are with respect to GND.

Note 6: The output pins RST and COMPX have internal pull-ups to V

of

CC3

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.

typically 6µA. However, external pull-up resistors may be used when faster

rise times are required or for V voltages greater than V

.

CC3

OH

Note 7: The V

reset override voltage is valid for an operating range less

CC5

than approximately 4.15V. Above this point the override is turned off and

the V pin functions normally.

CC5

17278fb

4

LTC1727/LTC1728

Typical perForMance cHaracTerisTics

V_CCAInput Current

ꢂs Input Voltage

V_CCAThreshold Voltage

ꢂs Temperature

Typiꢁal Transient Duration

ꢂs Comparator Oꢂerdriꢂe

450

2.0

1.5

1.015

1.010

1.005

1.000

0.995

0.990

0.985

T

= 25°C

T

= 25°C

A

400

350

300

250

200

150

100

50

RESET OCCURS

ABOVE CURVE

1.0

0.5

0

–0.5

–1.0

–1.5

–2.0

0

0.1

40 60

–60 –40 –20

TEMPERATURE (°C)

1

10

100

1

0

20

80 100

0.80 0.85 0.90 0.95

1.05 1.10 1.15 1.20

RESET COMPARATOR OVERDRIVE VOLTAGE (% OF V

)

INPUT VOLTAGE (V)

CC

1727/28 G03

1727/28 G01

1727/28 G02

Reset Pulse Width

ꢂs Temperature

RST, COMPX I_SINK

I_VCC25ꢂs Temperature

(LTC±727-2.5/LT±728-2.5)

1.5

ꢂs Supply Voltage

280

260

10

9

8

7

6

5

4

3

2

1

0

V

= 3.3V

T

= 25°C

CC3

A

1.4

1.3

1.2

1.1

1.0

0.9

0.8

0.7

0.6

0.5

= 2.5V

CC25

CCA

= 3.3V

V

= 0.4V

OL

240

220

200

180

160

V

= 0.2V

OL

140

–20

0

20 40

80 100

–60

80

–60 –40

60

–40 –20

20

TEMPERATURE (°C)

0

40

100

0

1

3

4

(V)

5

6

2

TEMPERATURE (°C)

V

OR V

CC3

CC5

1727/28 G04

1727/28 G06

1727/28 G05

I_VCC3ꢂs Temperature (LTC±727-

2.5/LTC±728-2.5/LTC±728-3.3)

I_VCC3ꢂs Temperature

(LTC±727-5/LTC±728-5)

I_VCC5ꢂs Temperature

(LTC±727-5/LTC±728-5)

15

14

13

12

11

10

9

15

14

13

12

11

10

9

1.5

1.4

1.3

1.2

1.1

1.0

0.9

0.8

0.7

0.6

0.5

V

= 5V

= 3.3V

V

CC5

V

CC3

V

CCA

= 5V

= 3.3V

V

= 3.3V

= 2.5V

CC5

CC3

CCA

CC3

CC25

CCA

= 3.3V

8

7

6

5

–60

20

TEMPERATURE (°C)

60 80

–40 –20

0

40

100

–60

20

TEMPERATURE (°C)

60 80

–60

20

TEMPERATURE (°C)

60 80

–40 –20

0

40

100

–40 –20

0

40

100

1727/28 G09

1727/28 G07

1727/28 G08

17278fb

5

LTC1727/LTC1728

Typical perForMance cHaracTerisTics

V_CC25Threshold Voltage

V_CC3Threshold Voltage

ꢂs Temperature

V_CC5Threshold Voltage

ꢂs Temperature

(LTC±727-5/LTC±728-5)

ꢂs Temperature

(LTC±727-2.5/LTC±728-2.5)

(All But LTC±728-±.8)

2.3750

2.3675

2.3600

2.3525

2.3450

2.3375

2.3300

2.3225

2.3150

2.3075

2.3000

3.135

3.125

3.115

3.105

3.095

3.085

3.075

3.065

3.055

3.045

3.035

4.750

4.725

4.700

4.675

4.650

4.625

4.600

–60

20

TEMPERATURE (°C)

60 80

80

–40 –20

0

40

100

–60

20

TEMPERATURE (°C)

60

20

–40 –20

0

40

100

–60 –40 –20

0

40 60 80 100

TEMPERATURE (°C)

1727/28 G10

1727/28 G11

1727/28 G12

I_VCC±8ꢂs Temperature

(LTC±728-±.8/LTC±728-3.3)

I_VCC3ꢂs Temperature

(LTC±728-±.8)

1.5

1.4

1.3

1.2

1.1

1.0

0.9

0.8

0.7

0.6

0.5

15

14

13

12

11

10

9

V

= 3V

V

= 3V

CC18

= 3V

CCA

CC3

= 1.8V

CC18

= 3V

CCA

8

7

6

5

–60 –40 –20

TEMPERATURE (°C)

20 40 60

80

–60

20

TEMPERATURE (°C)

60 80

0

100

–40 –20

0

40

100

1727/28 G13

1727/28 G14

V_CC±8Threshold Voltage

ꢂs Temperature

(LTC±728-±.8/LTC±728-3.3)

V_CC3Threshold Voltage

ꢂs Temperature (LTC±728-±.8)

2.845

2.835

2.825

2.815

2.805

2.795

2.785

2.775

2.765

1.710

1.700

1.690

1.680

1.670

1.660

1.650

40 60

TEMPERATURE (°C)

–60

20

TEMPERATURE (°C)

60 80

–60 –40 –20

0

20

80 100

–40 –20

0

40

100

1727/28 G16

1727/28 G15

17278fb

6

LTC1727/LTC1728

pin FuncTions ^{(LTC±727/LTC±728)}

V

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

COMPA(Pin5):V ComparatorOutputfortheLTC1727.

CC3

CCA

Pin. (3V Sense Input and Power Supply Pin for LTC1728-

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

1.8.) This pin provides power to the part when the voltage

V

.AssertedwhenV isaboveV .Deassertedwhen

CC3

CCA RTA

or if both the V

on V

is greater than the voltage on V /V

/V

.

is below V

and V

supply

Bypass to ground with a ≥0.1µF ceramic capa^Cc^Ci²t⁵or

.

pins are too low to power the internal bandgap reference

CC3

CC5

CC18

CCA

RTA

CC3

CC5

(typically <2.0V). Can be pulled greater than V

an external pull-up.

using

CC3

V

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

CC5

This pin is used on the LTC1727-5/LTC1728-5 to provide

power to the part when the voltage on V is greater

RST (Pin 6/Pin ±): Reset Logic Output. Active low, open-

CC5

than the voltage on V . Bypass to ground with a ≥0.1µF

drain logic output with weak pull-up to V . Can be pulled

CC3

ceramic capacito

r.

upgreaterthanV wheninterfacingto5Vlogic.Asserted

CC3

when one or all of the supplies are below trip thresholds

V

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

CC25

and held for 200ms after all supplies become valid.

Pin. This pin is used on the LTC1727-2.5/LTC1728-2.5 to

provide power to the part when the voltage on V is

COMP5 (Pin 7): V

Comparator Output for the

CC5

CC25

greater than the voltage on V . Bypass to ground with

LTC1727-5.Activehigh,open-drainlogicoutputwithweak

pull-up to V . Asserted when V is above V . Can

CC3

a ≥0.1µF ceramic capacito

r.

CC3

CC5

RT5

be pulled greater than V

using an external pull-up.

CC3

V

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

CC±8

Pin. This pin is used on the LTC1728-1.8/LTC1728-3.3 to

COMP25 (Pin 7): V

Comparator Output for the

CC25

provide power to the part when the voltage on V is

LTC1727-2.5. Active high, open-drain logic output with

weak pull-up to V . Asserted when V is above

CC18

greater than the voltage on V . Bypass to ground with

CC3

CC25

a ≥0.1µF ceramic capacito

r.

V

. Can be pulled greater than V using an external

RT25 CC3

pull-up.

V

(Pin3/Pin3):1VSense,HighImpedanceInput.Ifun-

CCA

used, it can be tied to either V

or V /V

/V

.

COMP3(Pin8):V ComparatorOutputfortheLTC1727.

CC3

CC5 CC25 CC18

CC3

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

GND (Pin 4/Pin 2): Ground.

V

. Asserted when V

is above V . Can be pulled

CC3

CC3 RT3

using an external pull-up.

greater than V

CC3

17278fb

7

LTC1727/LTC1728

block DiagraMs

LTC±727-5/LTC±727-2.5

V

CC3

6µA

–

+

COMP3

8

7

6

5

V

1

CC3

V

CC3

POWER

DETECT

6µA

V

INTERNAL

CC

COMP25/

COMP5

V

CC25

/

CC5

2

V

–

+

V

CC3

6µA

200ms PULSE GENERATOR

–

+

RST

V

3

4

CCA

200ms

DELAY

GND

V

CC3

6µA

COMPA

BANDGAP

REFERENCE

1727 BD1

17278fb

8

LTC1727/LTC1728

block DiagraMs

LTC±728-5/LTC±728-2.5/LTC±728-±.8/LTC±728-3.3

–

+

V

5

CC3

POWER

DETECT

V

INTERNAL

CC

V

CC3

V

/

CC5

6µA

V

4

CC25

V

CC18

–

+

200ms PULSE GENERATOR

1

RST

200ms

DELAY

–

+

V

3

2

CCA

GND

BANDGAP

REFERENCE

1727 BD2

TiMing DiagraM

V_CCMonitor Timing

V

RTX

V

CCX

t

RST

t

UV

1.5V

RST

COMPX

1727 TD01

17278fb

9

LTC1727/LTC1728

applicaTions inForMaTion

Supply Monitoring

Power-Down

The LTC1727 is a low power, high accuracy triple sup- On power-down, once any of the V inputs drop below

CC

ply monitoring circuit with three monitor outputs and a its threshold, RST is held at a logic low. A logic low of

200ms microprocessor reset output.

0.3V isguaranteed untilbothV and V /V

/V

CC3

CC5 CC25 CC18

drop below 1V.

The LTC1728 is a low power, high accuracy triple supply

monitoring circuit with a single 200ms microprocessor

reset output.

Glitꢁh Immunity

The RST output of the LTC1727/LTC1728 have two forms

ofglitchimmunitybuiltin.First,theinputmonitorsrequire

the input voltage to transition at least 10% of the input

All three V inputs must be above predetermined thresh-

CC

oldsforresetnottobeinvoked.TheLTC1727/LTC1728will

assert reset during power-up, power-down and brownout

threshold (0.1 • V ) below the input threshold for ap-

RTH

conditions on any one or all of the V inputs.

CC

proximately 50µs 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.

Power Deteꢁt

TheLTC1727/LTC1728arepoweredfromthe3.3V/3Vinput

pin (V ), the 1.8V input pin (V

), the 2.5V input pin

CC3

CC18

(V

) or the 5V input pin (V ), whichever pin has the

CC25

CC5

highest potential. This ensures the part pulls the RST pin

low as soon as either input pin is ≥1V.

TheindividualmonitoroutputsoftheLTC1727donothave

hysteresis and will track the monitor inputs relative to the

monitor’s input threshold (V , V

, V and V ). A

RTA RT25 RT3

RT5

Power-Up

veryslowmovinginputvoltagewithrippleridingonitmay

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.

Upon power-up, either the V /V

/

_CC25V

or V pin,

CC5

CC18 CC3

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

when either V /V /V or V reaches 1 . As long

as any one of the V inputs is below its predetermined

V

CC5 CC25 CC18

CC

CC3

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

CC

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

CC

450

400

350

300

250

200

150

100

50

drops below its predetermined threshold and remains

asserted until 200ms after all of the V inputs are above

CC

their thresholds.

On the LTC1727, each of the comparator outputs will be

lowuntiltheV inputthatismonitoredbythatcompara-

CC

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

CC5 CC25

or

CC3

V

/V

greater than 1V. The COMPA output requires

0

0.1

1

10

100

the internal bandgap reference to be valid before the

correct logic state can be output. Therefore, the COMPA

RESET MONITOR OVERDRIVE VOLTAGE (% OF V

)

CC

1727/28 F01

output will be held low until V

is above 1V and V

CCA

CC3

or V /V

is greater than 2V (typ).

Figure ±. Transient Duration ꢂs Comparator Oꢂerdriꢂe

CC5 CC25

17278fb

10

LTC1727/LTC1728

applicaTions inForMaTion

Oꢂerride Funꢁtions (5V Versions Only)

When monitoring either 3.3V or 5V with V

strapped

CC3

to V

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

CC5

The V

pin, if unused, can be tied to either V

or

CC3

CCA

appropriate range. The part handles this situation as

V

. This is an obvious solution since the trip points for

CC5

CC3

for V

shown in Figure 3. Above 1V and below V

, RST is held

RT3

and V

will always be greater than the trip point

CC5

low. From V to approximately 4.15V the part assumes

RT3

.

CCA

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 summa-

rizes the state of RST at various operating voltages with

The V

input trip point is disabled if its voltage is

CC5

equal to the voltage on V

25mV and the voltage on

CC3

V

is less than 4.15V. In this manner, the LTC1727-5/

CC5

LTC1728-5 will behave as a 3.3V monitor and V reset

CC5

capability will be disabled.

V

= V

.

CC3

Table ±. Oꢂerride Truth Table (V_CC3= V_CC5

INPUTS (V = V = V

CC5

The V

CC5

trip point is reenabled when the voltage on

CC5

V

is equal to the voltage on V

25mV and the

CC3

)

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.

)

CC

RST

—

0

CC3

CC5

0V ≤ V ≤ 1V

CC

1V ≤ V ≤ V

CC

RT3

V

RT3

≤ V ≤ 4.15V

1

CC

4.15V ≤ V ≤ V

0

CC

RT5

V

RT5

≤ V

1

CC

V

CC

3.3V OR 5V

LTC1728-5

5

4

3

2

R1

10k

V

CC3

CC5

CCA

1

TO SYSTEM

RESET

RST

GND

1727/28 F02

Figure 2. Single Supply Monitor with Others Disabled

5

V

= V

= 0V TO 5V

CCA

CC3

CC5

10k PULL-UP FROM RST TO V

CC3

4

3

2

1

0

1

2

3

4

5

SUPPLY VOLTAGE (V)

1727/28 F03

Figure 3. RST Voltage ꢂs Supply Voltage

17278fb

11

LTC1727/LTC1728

applicaTions inForMaTion

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

LTC±727-2.5/LTC±728-2.5/LTC±728-±.8/LTC±728-3.3

Oꢂerride Funꢁtions

TheV pin, ifunused, canbetiedtoeitherV orV /

CC25

CCA

CC3

V

. This is an obvious solution since the trip points for

CC18

from the V pin to the V pin. This prevents the part’s

CC5

CC3

and V

/V

will always be greater than the trip

CC3

CC25 CC18

CCA

internal override circuit from being activated. Without the

point for V . Likewise, the V

/V

, if unused, can

CC25 CC18

override circuit active, the RST pin stays low until V

CC5

be tied to V . V

must always be used. Tying V

to

CC3 CC3

CC3

reaches V

≅ 4.675V. (See Figure 5.)

RT5

V

/V

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

CC25 CC18

result in the continuous assertion of RST.

5V

LTC1728-5

D1

5

4

3

2

R1

10k

V

= V

= 0V TO 5V

CCA

CC3

CC5

10k PULL-UP FROM RST TO V

CC5

CCA

T

= 25°C

4

3

2

1

0

A

1

TO SYSTEM

RESET

RST

GND

D1: MMBD914 OR EQUIVALENT

0.1µF

1727/28 F04

Figure 4. LTC±728-5 Monitoring a Single 5V

Supply. D± Used to Aꢂoid RST High Near 3.±V

to 4V (See Figure 3).

0

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

(V)

V

CC5

1727/28 F05

Figure 5. RST Output Voltage

Charaꢁteristiꢁs of the Cirꢁuit in Figure 4

Typical applicaTions

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

LTC1728-5

5

4

3

2

1

SYSTEM RESET

3.3V

5V

V

RST

CC3

CC5

CCA

ADJUSTABLE SUPPLY

OR DC/DC FEEDBACK

DIVIDER

R1*

R2*

GND

1727/28 TA03

*TO PRESERVE THRESHOLD ACCURACY, SET PARALLEL

COMBINATION OF R1 AND R2 ≤ 66.5k

17278fb

12

LTC1727/LTC1728

Typical applicaTions

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

LTC1728-5

5

4

3

2

1

3.3V

5V

V

RST

SYSTEM RESET

CC3

CC5

CCA

GND

1727/28 TA04

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

3.3V OR

5V

LTC1728-5

10k

5

4

3

2

1

SYSTEM RESET

V

RST

CC3

CC5

CCA

R1*

ADJUSTABLE

SUPPLY

R2*

GND

1727/28 TA05

*TO PRESERVE THRESHOLD ACCURACY, SET PARALLEL

COMBINATION OF R1 AND R2 ≤ 66.5k

REFER TO LTC1728-5 OVERRIDE FUNCTIONS IN

THE APPLICATIONS INFORMATION SECTION

Dual Supply Monitor (3.3V Plus Adjustable)

3.3V

LTC1728-2.5

10k

5

4

3

2

1

V

RST

SYSTEM RESET

CC3

CC25

CCA

R1*

ADJUSTABLE

SUPPLY

R2*

GND

1727/28 TA06

*TO PRESERVE THRESHOLD ACCURACY, SET PARALLEL

COMBINATION OF R1 AND R2 ≤ 66.5k

Using V_CCATied to DC/DC Feedbaꢁk Diꢂider

2.9V

35.7k

1%

LTC1728-5

LTC1435

5

4

3

2

1

6

SYSTEM RESET

3.3V

V

RST

V

CC3

CC5

CCA

OSENSE

2.8k

1%

5V

22.1k

1%

GND

ADJUSTABLE

RESET TRIP

THRESHOLD 2.74V

1727/28 TA07

17278fb

13

LTC1727/LTC1728

package DescripTion

MS8 Paꢁkage

8-Lead Plastiꢁ MSOP

(Reference LTC DWG # 05-08-1660)

3.00 0.102

(.118 .004)

(NOTE 3)

0.52

(.0205)

REF

8

7 6

5

3.00 0.102

(.118 .004)

(NOTE 4)

4.90 0.152

(.193 .006)

DETAIL “A”

0.254

0.889 0.127

(.035 .005)

(.010)

0° – 6° TYP

GAUGE PLANE

1

2

3

4

5.23

3.20 – 3.45

(.206)

0.53 0.152

(.021 .006)

1.10

(.043)

MAX

0.86

(.034)

REF

(.126 – .136)

MIN

DETAIL “A”

0.18

(.007)

0.65

(.0256)

BSC

0.42 0.038

(.0165 .0015)

TYP

SEATING

PLANE

0.22 – 0.38

0.127 0.076

(.009 – .015)

RECOMMENDED SOLDER PAD LAYOUT

(.005 .003)

0.65

(.0256)

BSC

TYP

MSOP (MS8) 0204

NOTE:

1. DIMENSIONS IN MILLIMETER/(INCH)

2. DRAWING NOT TO SCALE

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

MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE

4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.

INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE

5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX

S8 Paꢁkage

8-Lead Plastiꢁ Small Outline (Narrow 0.±50)

(Reference LTC DWG # 05-08-1610)

.189 – .197

(4.801 – 5.004)

.045 .005

NOTE 3

.050 BSC

7

5

8

6

.245

MIN

.160 .005

.150 – .157

(3.810 – 3.988)

NOTE 3

.228 – .244

(5.791 – 6.197)

.030 .005

TYP

1

3

4

2

RECOMMENDED SOLDER PAD LAYOUT

.010 – .020

(0.254 – 0.508)

× 45°

.053 – .069

(1.346 – 1.752)

.004 – .010

(0.101 – 0.254)

.008 – .010

(0.203 – 0.254)

0°– 8° TYP

.016 – .050

(0.406 – 1.270)

.050

(1.270)

BSC

.014 – .019

(0.355 – 0.483)

TYP

NOTE:

INCHES

1. DIMENSIONS IN

(MILLIMETERS)

2. DRAWING NOT TO SCALE

3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.

MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)

SO8 0303

17278fb

14

LTC1727/LTC1728

package DescripTion

S5 Paꢁkage

5-Lead Plastiꢁ SOT-23

(Reference LTC DWG # 05-08-1633)

(Reference LTC DWG # 05-08-1635)

2.80 – 3.10

(.110 – .118)

(NOTE 3)

SOT-23

(Original)

SOT-23

(ThinSOT)

.90 – 1.45

1.00 MAX

A

A1

A2

L

(.035 – .057)

(.039 MAX)

.00 – .15

(.00 – .006)

.01 – .10

(.0004 – .004)

2.60 – 3.00

1.50 – 1.75

(.102 – .118) (.059 – .069)

(NOTE 3)

.90 – 1.30

(.035 – .051)

.80 – .90

(.031 – .035)

.35 – .55

(.014 – .021)

.30 – .50 REF

(.012 – .019 REF)

PIN ONE

.95

(.037)

REF

.25 – .50

(.010 – .020)

(5PLCS, NOTE 2)

.20

(.008)

A2

A

DATUM ‘A’

1.90

(.074)

REF

L

.09 – .20

(.004 – .008)

(NOTE 2)

A1

S5 SOT-23 0401

NOTE:

1. CONTROLLING DIMENSION: MILLIMETERS

MILLIMETERS

2. DIMENSIONS ARE IN

(INCHES)

3. DRAWING NOT TO SCALE

4. DIMENSIONS ARE INCLUSIVE OF PLATING

5. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR

6. MOLD FLASH SHALL NOT EXCEED .254mm

7. PACKAGE EIAJ REFERENCE IS:

SC-74A (EIAJ) FOR ORIGINAL

JEDEC MO-193 FOR THIN

17278fb

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 representa-

tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.

15

LTC1727/LTC1728

Typical applicaTion

Triple Supply Monitor with Manual Reset Button

12V ( 5ꢀ%

TRIP

( 0.17V%

V

= 11.2V

5V 3.3V

5

4

3

1

2

V

RST

CC3

100nF

LTC1728-5

R1

1.07M

0.1ꢀ

CC5

CCA

R3*

10k

5ꢀ

100nF

GND

R2

105k

0.1ꢀ

MANUAL

1727/28 TA02

RESET BUTTON

(NORMALLY OPEN%

V

CCA

V

=

(R1 + R2%

TRIP

R2

V

TRIP

– 1

*OPTIONAL RESISTOR RECOMMENDED

TO EXTEND ESD TOLERANCE

R1 = R2

(

%

CCA

relaTeD parTs

PART NUMBER

LTC690

DESCRIPTION

COMMENTS

5V Supply Monitor, Watchdog Timer and Battery Backup

3.3V Supply Monitor, Watchdog Timer and Battery Backup

5V Supply Monitor and Watchdog Timer

4.65V Threshold

2.9V Threshold

4.65V Threshold

LTC694-3.3

LTC699

LTC1232

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

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

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

4.37V/4.62V Threshold

LTC1326

4.725V, 3.118V, 1V Thresholds ( 0.75%)

2.363V, 3.118V, 1V Thresholds ( 0.75%)

LTC1326-2.5

LTC1443/LTC1444 Micropower Quad Comparators with 1% Reference

LTC1445

LTC1443 Has 1.182V Reference, LTC1444/LTC1445

Have 1.221V Reference and Adjustable Hysteresis

LTC1536

Precision Triple Supply Monitor for PCI Applications

Nanopower Comparator with 2% Reference

Meets PCI t

Timing Speciﬁcations

FAIL

LTC1540

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

Adjustable RESET and Watchdog Time Outs

Push-Pull RESET Output, SOT-23

LTC1726-2.5

LTC1726-5

LTC1985-1.8

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

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

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

17278fb

LT 0207 REV B • PRINTED IN USA

LinearTechnology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

16

●

 LINEAR TECHNOLOGY CORPORATION 1999

(408) 432-1900 FAX: (408) 434-0507 www.linear.com


型号：	LTC1727_15
厂家：	Linear
描述：	Micropower Precision Triple Supply Monitors in 8-Lead MSOP and 5-Lead SOT-23 Packages
文件：	总16页 (文件大小：203K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LTC1727_15 [Linear]

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