LTC1727 [Linear]

Micropower Precision Triple Supply Monitors in 8-Lead MSOP and 5-Lead SOT-23 Packages; 精密微三路电源采用8引脚MSOP监视和5引脚SOT- 23封装


型号：	LTC1727
厂家：	Linear
描述：	Micropower Precision Triple Supply Monitors in 8-Lead MSOP and 5-Lead SOT-23 Packages 精密微三路电源采用8引脚MSOP监视和5引脚SOT- 23封装
文件：	总16页 (文件大小：191K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LTC1727/LTC1728

Micropower Precision

Triple Supply Monitors

in 8-Lead MSOP and

5-Lead SOT-23 Packages

FEATURES

DESCRIPTIO

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.

■

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: 10µA Typ

■

200ms Reset Time Delay

Active Low RESET Output

The LTC1728 is functionally identical to the LTC1727

without the individual monitor outputs.

■

Power Supply Glitch Immunity

■

The RST output is guaranteed to be in the correct state for

_CC5/V_CC25/V_CC18or V_CC3down to 1V. The LTC1727/

LTC1728 may also be configured to monitor any one or

two V_CCinputs instead of three, depending on system

requirements.

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

Verylow(10µAtypical)supplycurrentmakestheLTC1727/

LTC1728 ideal for power conscious systems.

APPLICATIO S

■

The LTC1727 is available in an 8-lead MSOP or SO

package and the LTC1728 is available in a 5-lead SOT-23

package.

Desktop Computers

■

Notebook Computers

■

Intelligent Instruments

■

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

Portable Battery-Powered Equipment

■

Network Servers

TYPICAL APPLICATIO

3.3V

Triple Supply Monitor with Power Good Output

(3.3V, 2.5V and Adjustable)

1.8V

DC/DC

CONVERTER

SYSTEM

LOGIC

LTC1727-2.5

10k 10k

RST

CC3

POWER

GOOD

3.3V

2.5V

COMP3

COMP25

RST

CC3

LTC1728-5

CC25

CCA

CC5

61.9k

0.1µF

ADJUSTABLE

SUPPLY

SYSTEM

RESET

0.1µF

GND

CCA

GND COMPA

1727/28 TA08

1727/28 TA01

100k

LTC1727/LTC1728

W W W

ABSOLUTE AXI U RATI GS ^{(Notes 1, 2)}

Operating Temperature Range

V_CC3, V_CC5/V_CC25/V_CC18, V_CCA................... –0.3V to 7V

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

COMPA, COMP3, COMP25/COMP5

(Note 3) ............................................. – 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

PACKAGE RDER I FOR ATIO

TOP VIEW

COMP3

COMP25/

COMP5

CC3

8 COMP3

7 COMP25/COMP5

6 RST

CC25

RST 1

GND 2

5 V

CC3

CC5

CC3

CC5 CC25

GND

4 V

CCA

RST

CC5

CC25

CC18

CCA

5 COMPA

CCA

GND

COMPA

MS8 PACKAGE

8-LEAD PLASTIC MSOP

S5 PACKAGE

5-LEAD PLASTIC SOT-23

S8 PACKAGE

8-LEAD PLASTIC SO

_JMAX= 125°C, θ_JA= 200°C/W

T_JMAX= 125°C, θ_JA= 250°C/W

T_JMAX= 125°C, θ_JA= 150°C/W

ORDER

MS8

ORDER

PART NUMBER PART MARKING PART NUMBER PART MARKING PART NUMBER PART MARKING

LTHY

LTHX

172725

727I25

17275

LTPH

LTIA

LTHZ

LTC1727EMS8-2.5

LTC1727EMS8-5

LTC1727ES8-2.5

LTC1727IS8-2.5

LTC1727ES8-5

LTC1727IS8-5

LTC1728ES5-1.8

LTC1728ES5-2.5

LTC1728ES5-5

1727I5

Consult factory for Military grade parts.

ELECTRICAL CHARACTERISTICS

otherwise noted.

All except LTC1728-1.8. 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_CC3unless

SYMBOL PARAMETER

CONDITIONS

MIN

3.036

4.600

2.300

0.985

TYP

MAX

3.135

4.750

2.375

1.015

UNITS

Reset Threshold V

Input Threshold

●

3.086

4.675

2.338

1.000

RT3

CC3

Input Threshold (5V Version)

RT5

CC5

Input Threshold (2.5V Version)

RT25

RTA

CC25

Input Threshold

CCA

, 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

2.3

Supply Current

> V

CC3

●

µA

VCC3

CC3

CC5 CC25

< V , V

= 3.3V (Note 4)

CC5 CC25

CC3 CC3

Supply Current

< V , V = 2.5V (Note 4)

CC3 CC25

●

µA

VCC25

VCC5

VCCA

RST

CC25

Supply Current

Input Current

= 5V, V

< V

CC5

CCA

CC5

CCA

CC3

= 1V

–15

140

Reset Pulse Width

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

200

280

CC3

LTC1727/LTC1728

ELECTRICAL CHARACTERISTICS

otherwise noted.

All except LTC1728-1.8. 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_CC3unless

SYMBOL PARAMETER

Undervoltage Detect to RST

CONDITIONS

, V , V

MIN

TYP

MAX

UNITS

or V Less Than Reset

CCA

110

µs

CC5 CC25 CC3

or COMPX

Threshold V by More Than 1% (Note 5)

Output Voltage Low, RST, COMPX

= 2.5mA, V

= 100µA, V

= 3V, V /V

CC5 CC25

= 0V

= 1V

●

0.15

0.05

0.4

0.3

SINK

CC3

= 1V, V /V

CC5 CC25

= 0V, V /V

CC5 CC25

= 1V, V /V

CC5 CC25

Output Voltage High, RST, COMPX (Note 6)

= 1µA

●

CC3

– 1

SOURCE

LTC1727-5/LTC1728-5 Only

Reset Override Voltage (Note 7)

Override V

Ability to Assert RST

±0.025

CC3

OVR

CC5

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_CC3unless otherwise noted.

SYMBOL PARAMETER

CONDITIONS

MIN

2.760

1.656

0.985

TYP

MAX

2.850

1.710

1.015

UNITS

Reset Threshold V

Input Threshold

●

2.805

1.683

1.000

RT3

RT18

RTA

CC3

Input Threshold

CC18

CCA

CC18

Input Threshold

CCA

, V Operating Voltage

CC3 CC18

RST in Correct Logic State

CCOP

VCC3

Supply Current

> V

CC3

●

µA

CC3

CC18

< V , V

= 3V (Note 4)

CC3 CC3

Supply Current

< V , V = 1.8V (Note 4)

CC3 CC18

●

µA

µs

VCC18

VCCA

RST

CC18

Input Current

= 1V

CCA

–15

140

CCA

Reset Pulse Width

Undervoltage Detect to RST

RST Low (Note 5)

, V or V Less Than Reset (Note 5)

CCA

200

110

280

CC18 CC3

Threshold V by More Than 1%

Output Voltage Low, RST

= 2.5mA, V

= 100µA, V

= 3V, V

= 1V, V

= 0V, V

= 1V, V

= 0V

= 1V

●

0.15

0.05

0.4

0.3

SINK

CC3

CC18

Output Voltage High, RST

= 1µA (Note 6)

●

CC3

– 1

SOURCE

Note 1: Absolute Maximum Ratings are those values beyond which the life

of the device may be impaired.

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

(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

CC3

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

rise times are required or for V voltages greater than V

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.

CC3

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.

Note 4: Both V

and V /V

/V can act as the supply depending

CC5

CC3

CC5 CC25 CC18

on which pin has the greatest potential.

LTC1727/LTC1728

U W

TYPICAL PERFOR A CE CHARACTERISTICS

V_CCAThreshold Voltage

vs Temperature

Typical Transient Duration

vs Comparator Overdrive

_CCAInput Current

vs Input Voltage

450

400

350

300

250

200

150

100

2.0

1.5

1.015

1.010

1.005

1.000

0.995

0.990

0.985

T = 25°C

= 25°C

RESET OCCURS

ABOVE CURVE

1.0

0.5

–0.5

–1.0

–1.5

–2.0

0.1

100

–60 –40 –20

20 40 60 80 100

0.80 0.85 0.90 0.95

1.05 1.10 1.15 1.20

TEMPERATURE (°C)

RESET COMPARATOR OVERDRIVE VOLTAGE (% OF V

)

INPUT VOLTAGE (V)

1727/28 G03

1727/28 G01

1727/28 G02

Reset Pulse Width

vs Temperature

RST, COMPX I_SINK

vs Supply Voltage

I_VCC25vs Temperature

(LTC1727-2.5/LT1728-2.5)

1.5

280

260

= 25°C

= 3.3V

CC3

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

= 0.4V

240

220

200

180

160

= 0.2V

140

–20

20 40

80 100

–60

60 80

–60 –40

–40 –20

TEMPERATURE (°C)

100

OR V

(V)

CC5

TEMPERATURE (°C)

CC3

1727/28 G05

1727/28 G06

1727/28 G04

I_VCC3vs Temperature

(LTC1727-2.5/LT1728-2.5)

I_VCC3vs Temperature

(LTC1727-5/LTC1728-5)

I_VCC5vs Temperature

(LTC1727-5/LTC1728-5)

1.5

1.4

1.3

1.2

1.1

1.0

0.9

0.8

0.7

0.6

0.5

CC5

CC3

CCA

= 5V

= 3.3V

= 5V

= 3.3V

= 2.5V

CC5

CC3

CCA

CC3

CC25

CCA

= 3.3V

–60

TEMPERATURE (°C)

60 80

–40 –20

100

–60

60 80

–60

TEMPERATURE (°C)

60 80

–40 –20

TEMPERATURE (°C)

100

–40 –20

100

1727/28 G09

1727/28 G07

1727/28 G08

LTC1727/LTC1728

U W

TYPICAL PERFOR A CE CHARACTERISTICS

_CC3Threshold Voltage

V_CC5Threshold Voltage

vs Temperature

(LTC1727-5/LTC1728-5)

V_CC25Threshold Voltage

vs Temperature

(LTC1727-2.5/LTC1728-2.5)

vs Temperature

(All But LTC1728-1.8)

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

TEMPERATURE (°C)

60 80

–60

TEMPERATURE (°C)

60 80

–40 –20

100

–40 –20

100

–60

20 40

–40 –20

60 80

100

TEMPERATURE (°C)

1727/28 G10

1727/28 G11

1727/28 G12

I_VCC18vs Temperature

(LTC1728-1.8)

I_VCC3vs Temperature

(LTC1728-1.8)

1.5

1.4

1.3

1.2

1.1

1.0

0.9

0.8

0.7

0.6

0.5

= 3V

CC18

= 3V

CCA

CC3

= 1.8V

CC18

= 3V

CCA

–60 –40 –20

TEMPERATURE (°C)

20 40 60

–60

TEMPERATURE (°C)

60 80

100

–40 –20

100

1727/28 G13

1727/28 G14

V_CC18Threshold Voltage

vs Temperature (LTC1728-1.8)

V_CC3Threshold Voltage

vs Temperature (LTC1728-1.8)

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 –40 –20

80 100

–60

TEMPERATURE (°C)

–40 –20

100

1727/28 G15

1727/28 G16

LTC1727/LTC1728

PI FU CTIO S

(LTC1727/LTC1728)

V_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_CC3is greater than the voltage on

COMPA(Pin5):V_CCAComparatorOutputfortheLTC1727.

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

_CC3. Asserted when V_CCAis above V_RTA. Deasserted

when V_CCAis below V_RTAor if both the V_CC3and V_CC5

supply pins are too low to power the internal bandgap

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

V_CC3using an external pull-up.

_CC5/V_CC25/V_CC18. Bypass to ground with a ≥0.1µF

ceramic capacitor.

V_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_CC5is

greater than the voltage on V_CC3. Bypass to ground with

a ≥0.1µF ceramic capacitor.

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_CC3when interfacing to 5V logic. As-

sertedwhenoneorallofthesuppliesarebelowtripthresh-

olds and held for 200ms after all supplies become valid.

_CC25(Pin 2/Pin 4): 2.5V Sense Input and Power Supply

Pin. ThispinisusedontheLTC1727-2.5/LTC1728-2.5to

provide power to the part when the voltage on V_CC25is

greater than the voltage on V_CC3. Bypass to ground with

a ≥0.1µF ceramic capacitor.

COMP5 (Pin 7): V_CC5Comparator Output for the

LTC1727-5. Active high, open-drain logic output with

weak pull-up to V_CC3. Asserted when V_CC5is above V_RT5

CanbepulledgreaterthanV_CC3usinganexternalpull-up.

V_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_CC18is greater

thanthevoltageonV_CC3.Bypasstogroundwitha≥0.1µF

ceramic capacitor.

COMP25 (Pin 7): V_CC25Comparator Output for the

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

weak pull-up to V_CC3. Asserted when V_CC25is above

V_RT25. Can be pulled greater than V_CC3using an external

pull-up.

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

COMP3(Pin8):V_CC3ComparatorOutputfortheLTC1727.

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

V_CC3. Asserted when V_CC3is above V_RT3. Can be pulled

greater than V_CC3using an external pull-up.

unused, it can be tied to either V_CC3or V_CC5/V_CC25/V_CC18

GND (Pin 4/Pin 2): Ground.

LTC1727/LTC1728

BLOCK DIAGRA S

LTC1727-5/LTC1727-2.5

CC3

6µA

–

COMP3

CC3

POWER

DETECT

6µA

INTERNAL

COMP25/

COMP5

CC25

CC5

–

CC3

6µA

200ms PULSE GENERATOR

–

RST

CCA

200ms

DELAY

GND

CC3

6µA

COMPA

BANDGAP

REFERENCE

1727 BD1

LTC1727/LTC1728

BLOCK DIAGRA S

LTC1728-5/LTC1728-2.5/LTC1728-1.8

–

CC3

POWER

DETECT

INTERNAL

CC3

CC5

6µA

CC25

CC18

–

200ms PULSE GENERATOR

RST

200ms

DELAY

–

CCA

GND

BANDGAP

REFERENCE

1727 BD2

W U

TI I G DIAGRA

V_CCMonitor Timing

RTX

CCX

RST

1.5V

RST

COMPX

1727 TD01

LTC1727/LTC1728

W U U

APPLICATIO S I FOR ATIO

Supply Monitoring

Power-Down

The LTC1727 is a low power, high accuracy triple supply

monitoring circuit with three monitor outputs and a

200ms microprocessor reset output.

On power-down, once any of the V_CCinputs drop below

itsthreshold,RSTisheldatalogiclow.Alogiclowof0.3V

is guaranteed until both V_CC3and V_CC5/V_CC25/V_CC18drop

below 1V.

The LTC1728 is a low power, high accuracy triple supply

monitoring circuit with a single 200ms microprocessor

reset output.

Glitch 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

threshold (0.1 • V_RTH) below the input threshold for

approximately 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.

All three V_CCinputs must be above predetermined thresh-

olds for reset not to be invoked. The LTC1727/LTC1728

willassertresetduringpower-up,power-downandbrown-

out conditions on any one or all of the V_CCinputs.

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.

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_RT3and

V_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

tendencytointegratesignalsontheinputsimprovingtheir

immunity to noise and ripple.

Power-Up

Upon power-up, either the V_CC5/V_CC25/V_CC18or V_CC3pin,

canpowerthepart. ThisensuresthatRSTwillbelowwhen

either V_CC5/V_CC25/V_CC18or V_CC3reaches 1V. As long as

any one of the V_CCinputs is below its predetermined

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_CCinputs

drops below its predetermined threshold and remains

asserted until 200ms after all of the V_CCinputs are above

their thresholds.

450

400

350

300

250

200

150

100

On the LTC1727, each of the comparator outputs will be

lowuntiltheV_CCinputthatismonitoredbythatcompara-

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_CC3or

V_CC5/V_CC25greater 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_CCAis above 1V and V_CC3or

V_CC5/V_CC25is greater than 2V (typ).

0.1

100

RESET MONITOR OVERDRIVE VOLTAGE (% OF V

)

1727/28 F01

Figure 1. Transient Duration vs Comparator Overdrive

LTC1727/LTC1728

W U U

APPLICATIO S I FOR ATIO

When monitoring either 3.3V or 5V with V_CC3strapped to

V_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_RT3to 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.

Inmostsystemsthe5Vsupplywillpassthroughthe3.1V

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

Override Functions (5V Versions Only)

The V_CCApin, if unused, can be tied to either V_CC3or V_CC5

This is an obvious solution since the trip points for V_CC3

andV_CC5willalwaysbegreaterthanthetrippointforV_CCA

The V_CC5input trip point is disabled if its voltage is equal

to the voltage on V_CC3±25mV and the voltage on V_CC5is

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

LTC1728-5 will behave as a 3.3V monitor and V_CC5reset

capability will be disabled.

_CC3= V_CC5.

The V_CC5trip point is reenabled when the voltage on V_CC5

is equal to the voltage on V_CC3±25mV and the two inputs

aregreaterthanapproximately4.15V. Inthismanner, the

part can function as a 5V monitor with the 3.3V monitor

disabled.

Table 1. Override Truth Table (V_CC3= V_CC5

)

INPUTS (V = V = V

)

RST

—

CC3

CC5

0V ≤ V ≤ 1V

1V ≤ V ≤ V

RT3

≤ V ≤ 4.15V

RT3

4.15V ≤ V ≤ V

RT5

≤ V

RT5

3.3V OR 5V

LTC1728-5

10k

CC3

CC5

CCA

TO SYSTEM

RESET

RST

GND

1727/28 F02

Figure 2. Single Supply Monitor with Others Disabled

= V

= 0V TO 5V

CCA

CC3

CC5

10k PULL-UP FROM RST TO V

CC3

SUPPLY VOLTAGE (V)

1727/28 F03

Figure 3. RST Voltage vs Supply Voltage

LTC1727/LTC1728

W U U

APPLICATIO S I FOR ATIO

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_CC5pin to the V_CC3pin. 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_RT54.675V. (See Figure 5.)

LTC1727-2.5/LTC1728-2.5/LTC1728-1.8

Override Functions

TheV_CCApin, ifunused, canbetiedtoeitherV_CC3orV_CC25

V_CC18. This is an obvious solution since the trip points for

_CC3and V_CC25/V_CC18will always be greater than the trip

point for V_CCA. Likewise, the V_CC25/V_CC18, if unused, can

be tied to V_CC3. V_CC3must always be used. Tying V_CC3to

_CC25/V_CC18and operating off of a 2.5V/1.8V supply will

result in the continuous assertion of RST.

LTC1728-5

10k

CC3

CC5

CCA

TO SYSTEM

RESET

RST

GND

D1: MMBD914 OR EQUIVALENT

0.1µF

1727/28 F04

Figure 4. LTC1728-5 Monitoring a Single 5V

Supply. D1 Used to Avoid RST High Near 3.1V

to 4V (See Figure 3).

CC5

= V

CCA

= 0V TO 5V

10k PULL-UP FROM RST TO V

CC5

= 25°C

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

(V)

CC5

1727/28 F05

Figure 5. RST Output Voltage

Characteristics of the Circuit in Figure 4

LTC1727/LTC1728

TYPICAL APPLICATIO S

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

LTC1728-5

SYSTEM RESET

3.3V

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

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

LTC1728-5

3.3V

RST

SYSTEM RESET

CC3

CC5

CCA

GND

1727/28 TA04

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

3.3V OR

LTC1728-5

10k

SYSTEM RESET

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

LTC1727/LTC1728

TYPICAL APPLICATIO S

Dual Supply Monitor (3.3V Plus Adjustable)

3.3V

LTC1728-2.5

10k

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 Feedback Divider

2.9V

35.7k

LTC1728-5

LTC1435

SYSTEM RESET

3.3V

RST

CC3

CC5

CCA

OSENSE

2.8k

22.1k

GND

ADJUSTABLE

RESET TRIP

THRESHOLD 2.74V

1727/28 TA07

LTC1727/LTC1728

Dimensions in inches (millimeters) unless otherwise noted.

PACKAGE DESCRIPTIO

MS8 Package

8-Lead Plastic MSOP

(LTC DWG # 05-08-1660)

0.118 ± 0.004*

(3.00 ± 0.102)

0.118 ± 0.004**

(3.00 ± 0.102)

0.193 ± 0.006

(4.90 ± 0.15)

0.040 ± 0.006

(1.02 ± 0.15)

0.034 ± 0.004

(0.86 ± 0.102)

0.007

(0.18)

0° – 6° TYP

SEATING

PLANE

0.012

(0.30)

REF

0.021 ± 0.006

(0.53 ± 0.015)

0.006 ± 0.004

(0.15 ± 0.102)

0.0256

(0.65)

BSC

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

S5 Package

5-Lead Plastic SOT-23

(LTC DWG # 05-08-1633)

2.80 – 3.00

(0.110 – 0.118)

(NOTE 3)

0.95

(0.037)

REF

1.90

(0.074)

REF

2.60 – 3.00

(0.102 – 0.118)

1.50 – 1.75

(0.059 – 0.069)

0.00 – 0.15

(0.00 – 0.006)

0.90 – 1.45

(0.035 – 0.057)

0.35 – 0.55

(0.014 – 0.022)

0.35 – 0.50

(0.014 – 0.020)

FIVE PLACES (NOTE 2)

0.90 – 1.30

(0.035 – 0.051)

S5 SOT-23 0599

0.09 – 0.20

(0.004 – 0.008)

(NOTE 2)

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)

LTC1727/LTC1728

Dimensions in inches (millimeters) unless otherwise noted.

PACKAGE DESCRIPTIO

S8 Package

8-Lead Plastic Small Outline (Narrow 0.150)

(LTC DWG # 05-08-1610)

0.189 – 0.197*

(4.801 – 5.004)

0.150 – 0.157**

(3.810 – 3.988)

0.228 – 0.244

(5.791 – 6.197)

0.010 – 0.020

(0.254 – 0.508)

× 45°

0.053 – 0.069

(1.346 – 1.752)

0.004 – 0.010

(0.101 – 0.254)

0.008 – 0.010

(0.203 – 0.254)

0°– 8° TYP

0.016 – 0.050

(0.406 – 1.270)

0.050

(1.270)

BSC

0.014 – 0.019

(0.355 – 0.483)

TYP

*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

SO8 1298

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

TYPICAL APPLICATIO

Triple Supply Monitor with Manual Reset Button

12V (±5%)

TRIP

= 11.2V

(±0.17V)

5V 3.3V

RST

CC3

100nF

LTC1728-5

CC5

R3*

10k

1.07M

100nF

0.1%

GND

CCA

105k

0.1%

MANUAL

1727/28 TA02

RESET BUTTON

(NORMALLY OPEN)

CCA

(R1 + R2)

TRIP

– 1

*OPTIONAL RESISTOR RECOMMENDED

TO EXTEND ESD TOLERANCE

R1 = R2

(

)

CCA

RELATED PARTS

PART NUMBER

DESCRIPTION

COMMENTS

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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

LTC694-3.3

LTC699

2.9V Threshold

4.65V Threshold

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

Micropower Quad Comparators with 1% Reference

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

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

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

LINEAR TECHNOLOGY CORPORATION 1999

LinearTechnology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

●

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

LTC1727 [Linear]

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