LTC1726ES8-5#PBF_技术文档

LTC1726

Triple Supply Monitor and

µP Supervisor with Adjustable

Reset and Watchdog Timer

FeaTures

DescripTion

The LTC^®1726 is a triple supply monitor and microproces-

sorsupervisorycircuitwithadjustableresetandwatchdog

functions intended for systems with multiple supply volt-

ages. The part has a common open-drain reset output

withanadjustabledelay. Theresetandwatchdogtime-out

periods are both adjustable using external capacitors.

n

Monitors Three Inputs Simultaneously

LTC1726-5: 5V, 3.3V and ADJ

LTC1726-2.5: 2.5V, 3.3V and ADJ

n

1.5ꢀ Threshold Accuracy Over Temperature

n

Low Supply Current: 16µA Typ

n

Adjustable Reset Timeout

n

Adjustable Watchdog Timeout

Tight 1.5% accuracy specifications and glitch immunity

ensure reliable reset operation without false triggering.

n

Active Low Open-Drain Reset Output

n

Power Supply Glitch Immunity

Guaranteed RESET for V

MS8 and SO-8 Packages

n

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

≥ 1V or V

/V

≥ 1V

CC3

CC25 CC5

V

/V

or V down to 1V. The LTC1726 may also be

CC5 CC25 CC3

configured to monitor any one or two V inputs instead

CC

of three, depending on system requirements.

applicaTions

The low (16µA typical) supply current makes the LTC1726

ideal for power-conscious systems.

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and

ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property

of their respective owners.

n

Desktop Computers

n

Notebook Computers

n

Intelligent Instruments

Portable Battery-Powered Equipment

Network Servers

n

Typical applicaTion

A 3.3V, 5V and 1.8V Monitor

A 3.3V, 2.5V and 1.8V Monitor

1.8V

TRIP

1.8V

TRIP

(V

= 1.665V)

(V

= 1.665V)

3.3V

2.5V

R1

66.5k

1%

R1

66.5k

1%

3.3V

5V

0.1µF

R2

100k

1%

R2

100k

1%

2

1

3

2

1

3

C

RT

47nF

C

RT

V

CC25 CC3 CCA

47nF

CC5 CC3 CCA

8

7

6

5

8

7

6

5

RT

RST

RESET

µP

RT

RST

LTC1726-5

WDI

RESET

µP

C

WT

LTC1726-2.5

47nF

WT

WDI

I/O

WT

I/O

GND

4

GND

4

1726 TA02

1726 TA01

t

= 155ms

= 1s

t

= 155ms

= 1s

RT

WT

RT

WT

1726fd

1

For more information www.linear.com/LTC1726

LTC1726

(Notes 1, 2)

absoluTe MaxiMuM raTings

Terminal Voltage

Operating Temperature Range (Note 3)

V

, V /V

, V

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

LTC1726E, LTC1726I............................–40°C to 85°C

LTC1726H.......................................... –40°C to 125°C

Storage Temperature Range .................. –65°C to 150°C

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

CC3 CC5 CC25 CCA

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

WDI ......................................................... –0.3V to 7V

RT, WT..................................................... –0.3V to 7V

pin conFiguraTion

TOP VIEW

V

1

2

3

4

8

7

6

5

RT

CC3

V

1

2

3

4

8 RT

CC3

V

/V

WT

RST

WDI

CC25 CC5

V

/V

7 WT

6 RST

5 WDI

CC25 CC5

V

GND

CCA

V

CCA

GND

MS8 PACKAGE

8-LEAD PLASTIC MSOP

= 125°C, θ = 200°C/W

S8 PACKAGE

8-LEAD PLASTIC SO

= 125°C, θ = 150°C/W

T

JMAX

JA

T

JMAX

JA

orDer inForMaTion

LEAD FREE FINISH

TAPE AND REEL

PART MARKING

LTKZ

PACKAGE DESCRIPTION

8-Lead Plastic MSOP

8-Lead Plastic SO

TEMPERATURE RANGE

–40°C to 85°C

–40°C to 125°C

–40°C to 85°C

LTC1726EMS8-2.5#PBF

LTC1726EMS8-5#PBF

LTC1726HMS8-5#PBF

LTC1726ES8-2.5#PBF

LTC1726ES8-5#PBF

LTC1726IS8-2.5#PBF

LTC1726IS8-5#PBF

LTC1726EMS8-2.5#TRPBF

LTC1726EMS8-5#TRPBF

LTC1726HMS8-5#TRPBF

LTC1726ES8-2.5#TRPBF

LTC1726ES8-5#TRPBF

LTC1726IS8-2.5#TRPBF

LTC1726IS8-5#TRPBF

LTLA

172625

17265

8-Lead Plastic SO

726I25

1726I5

8-Lead Plastic SO

Consult LTC Marketing for parts specified with wider operating temperature ranges.

Consult LTC Marketing for information on non-standard lead based finish parts.

For more information on lead free part marking, go to: http://www.linear.com/leadfree/

For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/

1726fd

2

For more information www.linear.com/LTC1726

LTC1726

elecTrical characTerisTics ^Thel denotes the 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 otherwise noted.

SYMBOL PARAMETER

CONDITIONS

Input Threshold

MIN

TYP

MAX

UNITS

V

Reset Threshold V

V

CC3

RT3

CC3

CC5

l

3.036

3.023

3.085

3.135

3.147

V

H-Grade

Input Threshold (5V Version)

V

RT5

Reset Threshold V

V

CC5

l

4.600

4.582

4.675

4.750

4.769

V

H-Grade

l

V

Reset Threshold V

V

Input Threshold (2.5V Version),

CC25

2.300

2.337

2.375

V

RT25

CC25

Input Threshold

RTA

CCA

l

0.985

0.978

1.000

1.015

1.022

V

H-Grade

l

V

or V Operating Voltage

CC5

RST in Correct Logic State

1

7

V

CC

CC3

l

I

Supply Current

V

/V

> V

CC3

1

16

2

30

µA

VCC3

CC5 CC25

/V

< V , V

= 3.3V

CC5 CC25

CC3 CC3

l

I

V

Supply Current

V

= 5V

16

1

30

2

µA

nA

VCC5

VCC25

VCCA

CC5

Supply Current

< V , V

= 2.5V (Note 4)

CC25

CC3 CC25

Input Current

= 1V

CCA

–15

0

15

CCA

RT Charge Current Out

= 0V

RT

l

1.4

1.3

2

2.6

µA

H-Grade

V = 0V

WT

WT Charge Current Out

l

1.4

1.3

2

2.6

µA

H-Grade

V = 1.3V

RT

RT Discharge Current Out

WT Discharge Current Out

Reset Time-Out Period Variation

l

14

13

20

26

28

µA

H-Grade

= 1.3V

V

WT

l

14

13

20

26

28

µA

H-Grade

C = 1500pF Deviation from t = 5ms (Note 5)

RT

∆t

RT

l

–30

–45

0

30

45

%

H-Grade

/V , V

t

UV

V

Undervoltage Detect to RST

V

or V Less Than Reset

CCA

130

µs

CC

CC25 CC5 CC3

Threshold V by More Than 1%

RT

l

V

RST Output Voltage High (Note 6)

RST Output Voltage Low

I

= 1µA

V

CC3

– 1

V

OH

SOURCE

l

I

= 2.5mA, V /V

= 0V

CC5 CC25

0.15

0.05

0.4

0.3

V

OL

SINK

CC5 CC25

= 100µA, V

= 1V, V /V

= 0V

= 1V

CC3

= 0V, V /V

CC5 CC25

= 1V, V /V

CC5 CC25

l

V

WDI Input Threshold High

WDI Input Threshold Low

WDI Pulse Width

0.7 • V

V

IH

CC3

0.3 • V

IL

CC3

t

WP

40

ns

∆t

Watchdog Time-Out Period Variation

C

= 1500pF Deviation from t = 33ms (Note 5)

WT WT

WT

l

–30

–45

0

30

45

%

H-Grade

l

WDI Leakage Current

1

µA

LTC1726-5 Only

V

OVR

V

Reset Override Voltage (Note 7) Override V

Ability to Assert RST

V

CC3

0.025

V

CC5

1726fd

3

For more information www.linear.com/LTC1726

LTC1726

elecTrical characTerisTics

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 4: Both V

and V

/V

can act as the supply depending on

CC3

CC25 CC5

which pin has the greatest potential.

Note 5: Timing measured with respect to RST passing through 1.5V.

Note 6: The output pin RST has a weak internal pull-up to V of typically

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

times are required or for V voltages greater than V

CC3

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

Note 3: The LTC1726E is guaranteed to meet performance specifications

from 0°C to 70°C. Specifications over the –40°C to 85°C operating

temperature range are assured by design, characterization and correlation

with statistical process controls.

.

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

Typical perForMance characTerisTics

V_CC5Threshold Voltage

vs Temperature (LTC1726-5)

V_CC3Threshold Voltage

vs Temperature

V_CCAThreshold Voltage

vs Temperature

3.135

3.125

3.115

3.105

3.095

3.085

3.075

3.065

3.055

3.045

3.035

1.015

1.010

1.005

1.000

0.995

0.990

0.985

4.750

4.725

4.700

4.675

4.650

4.625

4.600

40 60

TEMPERATURE (°C)

–60 –40 –20

0

20

80 100

20

TEMPERATURE (°C)

–60 –40 –20

0

40 60 80 100

–60

20

TEMPERATURE (°C)

60 80

–40 –20

0

40

100

1726 G01

1726 G03

1726 G02

V_CC25Threshold Voltage

vs Temperature (LTC1726-2.5)

I_VCC5vs Temperature (LTC1726-5)

I_VCC3vs Temperature (LTC1726-5)

2.375

2.360

2.345

2.330

2.315

2.300

20

19

18

17

16

15

14

13

12

11

10

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

= 5V

= 3.3V

CC5

CC3

CC5

CC3

–60 –40 –20

0

20

40 60 80 100

–60

20

TEMPERATURE (°C)

60 80

80

–40 –20

0

40

100

–60

20

TEMPERATURE (°C)

60

–40 –20

0

40

100

TEMPERATURE (°C)

1726 G04

1726 G05

1726 G06

1726fd

4

For more information www.linear.com/LTC1726

LTC1726

Typical perForMance characTerisTics

I_VCC25vs Temperature

(LTC1726-2.5)

I_VCC3vs Temperature

(LTC1726-2.5)

Typical Transient Duration

vs Comparator Overdrive

1.5

1.4

1.3

1.2

1.1

1.0

0.9

0.8

0.7

0.6

0.5

20

19

18

17

16

15

14

13

12

11

10

700

600

500

400

300

200

100

0

V

= 3.3V

= 2.5V

T = 25°C

A

V

= 3.3V

= 2.5V

CC3

CC25

CC3

CC25

RESET OCCURS

ABOVE CURVE

–60

20

TEMPERATURE (°C)

60 80

0.1

1

10

100

–40 –20

0

40

100

80

–60

20

TEMPERATURE (°C)

60

–40 –20

0

40

100

RESET COMPARATOR OVERDRIVE VOLTAGE (% OF V

)

CC

1726 G07

1726 G08

1726 G09

V_CCAInput Current

vs Input Voltage

Watchdog Time-Out Period

vs Temperature

Reset Pulse Width vs

Temperature

40

38

6.0

2.0

1.5

C

= 1500pF

C

= 1500pF

RT

WT

T

= 25°C

A

5.8

5.6

5.4

5.2

5.0

4.8

4.6

4.4

4.2

4.0

(SILVER MICA)

1.0

36

0.5

34

32

30

28

0

–0.5

–1.0

–1.5

–2.0

26

–20

0

20 40

100

–60 –40

60 80

1

80

0.80 0.85 0.90 0.95

1.05 1.10 1.15 1.20

–60

20

TEMPERATURE (°C)

60

–40 –20

0

40

100

TEMPERATURE (°C)

INPUT VOLTAGE (V)

1726 G10

1726 G14

1726 G11

Watchdog Time-Out Period vs

Capacitance

Reset Time-Out Period vs

Capacitance

RST Output Voltage vs

Supply Voltage (LTC1726-2.5)

100

10

1000

100

10

V

= V

CC25 CCA

T

= 25°C

T

= 25°C

CC3

A

10k PULL-UP FROM V

TO RST

CC3

3

T

= 25°C

A

1

100m

10m

1m

1

2

1

100m

10m

1m

100

10

0

100

2

3

0

1

100n

10

1p 10p 100p 1n

10n

1

100n

1

1p 10p 100p 1n

10n

1

V

(V)

C

(FARAD)

C

(FARAD)

CC3

RT

WT

1726 F13

1726 G15

1726 G12

1726fd

5

For more information www.linear.com/LTC1726

LTC1726

pin FuncTions

V

(Pin 1): 3.3V Sense Input. This pin also supplies

pin should be connected to either V or ground and WT

CC3

power to the part when the voltage on this pin is greater

must be grounded.

than the voltage on V /V . Bypass this pin to ground

with a 0.1µF or larger ceramic capacitor.

CC25 CC5

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

logic outputwith weak pull-up to V . Asserted whenone

CC3

V

(Pin 2): 5V Sense Input (LTC1726-5). This pin also

or more of the supplies are below trip thresholds. After all

supplies become valid, the reset remains asserted for the

period set by the capacitor on the RT pin. The watchdog

timer can also trigger the reset whenever the watchdog

time-out period is exceeded. This pin can be pulled up

CC5

supplies power to the part when the voltage on this pin is

greaterthanthevoltageonV .Bypassthispintoground

with a 0.1µF or larger ceramic capacitor.

CC3

V

(Pin 2): 2.5V Sense Input (LTC1726-2.5). This pin

CC25

greater than V

when interfacing to 5V logic.

CC3

also supplies power to the part when the voltage on this

pin is greater than the voltage on V . Bypass this pin to

ground with a 0.1µF or larger ceramic capacitor.

WT (Pin 7): Watchdog Time-Out Input. Place a capacitor

between this pin and ground to adjust the watchdog time-

out period. To determine the watchdog time-out period:

CC3

V

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

CCA

it can be tied to either V , V

or V

.

t = 21.8 • C

WT WT

CC3 CC5

CC25

GND (Pin 4): Ground.

with t in µs and C in pF. As an example, a 47nF

WT WT

capacitor will generate a 1s watchdog time-out period.

The watchdog function can be disabled by connecting

this pin to ground.

WDI (Pin 5): Watchdog Input. A logic input whose rising

or falling edge must occur on this pin within the selected

watchdog time-out period or a reset pulse will occur.

The watchdog time-out period is set by the value of the

capacitor that is placed on the WT pin. The rising or falling

edge of this pin clears the voltage on the WT capacitor,

preventing a reset pulse from occurring. If the watchdog

timerisnotcleared, aresetpulsewilloccur. Thewatchdog

timer is cleared during a reset and restarts when the reset

is deasserted. When disabling the watchdog function, this

RT (Pin8):ResetTime-OutInput.Placeacapacitorbetween

this pin and ground to adjust the reset time-out period.

To determine the reset time-out period:

t

= 3.30 • C

RT

with t in µs and C in pF. As an example, a 47nF capaci-

RT

tor will generate a 155ms reset time-out period.

1726fd

6

For more information www.linear.com/LTC1726

LTC1726

block DiagraM

2µA

WT

WDI

5

WATCHDOG

TIMER

TRANSITION DETECT

7

+

C

WT

V

CC3

–

+

22µA

1

2

V

CC3

POWER

DETECT

V

CC

INTERNAL

V

/V

CC5 CC25

–

+

V

/V

CC5 CC25

V

CC3

6µA

RST

CCA

–

6

ADJUSTABLE

RESET

PULSE

GENERATOR

3

4

GND

1V

+

2µA

22µA

BANDGAP

REFERENCE

RT

8

1726 BD

+

C

RT

TiMing DiagraM

V_CCMonitor Timing

Watchdog Timing Diagram

V

RTX

t

WT

WDI

RST

V

WP

WT

CCX

t

RT

t

RT

t

UV

1.5V

RST

1726 TD02

1726 TD01

1726fd

7

For more information www.linear.com/LTC1726

LTC1726

applicaTions inForMaTion

Supply Monitoring

are greater than approximately 4.15V. In this manner, the

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

disabled.

The LTC1726 is a low power, high accuracy triple supply

monitor and watchdog timer. The watchdog and reset

periods are both adjustable using external capacitors.

When monitoring either 3.3V or 5V with V strapped to

CC3

V

CC5

, (see Figure 1) the part determines which is the ap-

All three V inputs must be above predetermined thresh-

CC

propriate range. The part handles this situation as shown

in Figure 2. Above 1V and below V , RST is held low.

olds for reset not to be asserted. The LTC1726 will assert

RT3

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

From V

to approximately 4.15V, the part assumes

RT3

tions on any one or all of the V inputs.

CC

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

outputwillbehaveasdesired.Table1summarizesthestate

Upon power-up, either the V /V

or V

pin can

CC3

CC5 CC25

power the drive circuits for the RST pin. This ensures that

RST will be low when either V /V

or V

reaches

CC5 CC25

CC3

1V. As long as any one of the V inputs is below its pre-

CC

determinedthreshold, RSTwillstayalogiclow. Onceallof

of RST at various operating voltages with V

= V

.

CC3

CC5

the V inputs rise above their thresholds, the adjustable

CC

Table 1. Override Truth Table (V_CC3= V_CC5

)

reset timer is started and RST is released after the reset

INPUTS (V

= V

= V )

CC

RST

—

0

CC3

CC5

time-out period.

0V ≤ V ≤ 1V

CC

On power-down, once any of the V inputs drops below

CC

1V ≤ V ≤ V

CC

RT3

its threshold, RST is held at a logic low. A logic low of

V

≤ V ≤ 4.15V

1

RT3

CC

0.3V is guaranteed until both V

below 1V.

and V /V

drop

CC3

CC5 CC25

4.15V ≤ V ≤ V

0

CC

RT5

V

≤ V

1

RT5

CC

3V or 5V/2.5V Power Detect

V

CC

3.3V OR 5V

LTC1726-5

Since the LTC1726 is a multisupply monitor, it will be

required to assert reset as soon as there is power on any

one of the monitor inputs. Therefore, the part derives its

1

2

3

4

R1

10k

V

CC3

CC5

CCA

6

TO SYSTEM

RESET

RST

powerfromeithertheV orV /V

input,whichever

CC3

CC5 CC25

GND

1726 F01

pin has the greatest potential. This ensures the part pulls

the RST pin low as soon as either input pin is ≥1V. The

adjustable input is excluded from being a potential supply

pin because of its 1V nominal operating range.

PINS 5, 7 AND 8 NOT SHOWN FOR CLARITY

Figure 1. Single Supply Monitor with Others Disabled

5

V

= V

= 0V TO 5V

CCA

CC3

CC5

10k PULL-UP FROM RST TO V

CC3

Override Functions (5V Versions Only)

T

= 25°C

4

3

A

The V

pin, if unused, can be tied to either V or V

CC5

.

CCA

CC3

This is an obvious solution since the trip points for V

CC3

andV willalwaysbegreaterthanthetrippointforV

.

CC5

CCA

2

1

0

The V

input trip point is disabled if its voltage is equal

CC5

to the voltage on V

25mV and the voltage on V

is

CC3

CC5

less than 4.15V. In this manner the LTC1726-5 behaves

as a 3.3V monitor and the 5V reset function is disabled.

0

1

2

3

4

5

The V trip point is re-enabled when the voltage on V

SUPPLY VOLTAGE (V)

CC5

1726 F02

is equal to the voltage on V

25mV and the two inputs

CC3

Figure 2. RST Voltage vs Supply Voltage

1726fd

8

For more information www.linear.com/LTC1726

LTC1726

applicaTions inForMaTion

Figure 3 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 LTC1726-5 while dropping ≈0.6V

Watchdog Timer

The watchdog circuit monitors a µP’s activity. The µP is

required to change the logic state of the WDI pin on a

periodic basis in order to clear the watchdog timer and

prevent the LTC1726 from issuing a reset.

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

CC5

CC3

internal override circuit from being activated. Without the

During power-up, the watchdog timer remains cleared

while reset is asserted. As soon as the reset timer times

out, the watchdog timer is started. The watchdog timer

will continue to run until a transition is detected on the

WDI input or until the watchdog timer times out. Once the

watchdog timer times out, the internal circuitry asserts

the reset and starts the reset timer. When the reset timer

times out and reset is deasserted, the watchdog timer is

again started. If no WDI transition is received within the

watchdog time-out period, the reset will be reasserted at

the end of the watchdog time-out period. If a transition is

received on the WDI input during the watchdog time-out

period, the watchdog timer will be restarted and reset will

remain deasserted.

override circuit active, the RST pin stays low until V

CC5

reaches V

≅ 4.675V. (See Figure 4.)

RT5

5V

LTC1726-5

D1

1

2

3

4

R1

10k

V

CC3

CC5

CCA

6

TO SYSTEM

RESET

RST

GND

0.1µF

1726 F03

D1: MMBD914 OR EQUIVALENT

PINS 5, 7 AND 8 NOT SHOWN FOR CLARITY

Figure 3. LTC1726-5 Monitoring a Single 5V

Supply. D1 Used to Avoid RST High Near 3.1V

to 4V (See Figure 2).

5

V

= V

= 0V TO 5V

CCA

CC5

Selecting the Reset and Watchdog

Time-Out Capacitors

10k PULL-UP FROM RST TO V

CC5

T

= 25°C

4

3

2

1

0

A

The reset time-out period is adjustable in order to accom-

modate a variety of µP applications. The reset time-out

period, t , is adjusted by connecting a capacitor, C ,

RT

betweentheRT pinandground. Thevalueofthiscapacitor

is determined as follows:

C

= t /3.30

RT

0

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

(V)

with C in pF and t in µs (i.e., 1500pF ⇒ 4.95ms).

RT

V

CC5

The capacitor should be a low leakage type. A ceramic

1726 F04

capacitor is recommended.

Figure 4. RST Output Voltage

Characteristics of the Circuit in Figure 3

Thewatchdogperiodisalsoadjustablesothatthewatchdog

time-out period can be optimized for software execution.

LTC1726-2.5 Override Functions

The V pin, if unused, can be tied to either V

Thewatchdogtime-outperiod,t ,isadjustedbyconnect-

WT

ingacapacitor,C ,betweentheWT pinandground.Once

WT

or

CCA

CC3

theoptimumwatchdogtime-outperiod(t )isdetermined,

WT

V

. This is an obvious solution since the trip points for

CC25

CC3

the value of the capacitor is calculated as follows:

and V

CCA

CC3 CC3

will always be greater than the trip point

CC25

for V . Likewise, the V

, if unused, can be tied to

C

WT

= t /21.8

WT

CC25

V

. V must always be used. Tying V to V

and

CC25

CC3

with C in pF and t in µs (i.e., 1500pF ⇒ 32.7ms).

WT

operating off of a 2.5V supply will result in the continuous

The capacitor should be a low leakage type. A ceramic

assertion of RST.

capacitor is recommended.

1726fd

9

For more information www.linear.com/LTC1726

LTC1726

Typical applicaTions

Disabling the Watchdog Timer

LTC1726-5/LTC1726-2.5

C

RT

1

8

7

6

5

3.3V

V

RT

WT

CC3

2

3

4

5V/2.5V

/V

CC5 CC25

R1*

SYSTEM

RESET

ADJUSTABLE

SUPPLY

RST

WDI

CCA

R2*

GND

1726 TA03

*TO PRESERVE THRESHOLD ACCURACY, SET PARALLEL

COMBINATION OF R1 AND R2 ≤ 66.5k

THE WATCHDOG TIMER CAN BE DISABLED BY CONNECTING

THE WDI AND WT PINS TO GROUND. THE PART WILL ACT

STRICTLY AS A TRIPLE SUPPLY MONITOR WITH AN

ADJUSTABLE RESET TIME-OUT PERIOD

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

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

LTC1726-5

C

RT

1

2

3

4

1

2

3

4

8

7

6

5

8

7

6

5

3.3V

5V

V

RT

WT

3.3V

5V

V

RT

CC3

CC5

CCA

CC3

CC5

CCA

C

WT

RST

WDI

ADJUSTABLE SUPPLY

OR DC/DC FEEDBACK

DIVIDER

R1*

SYSTEM RESET

WDI

SYSTEM RESET

WDI

RST

WDI

R2*

GND

1726 TA05

1726 TA04

*TO PRESERVE THRESHOLD ACCURACY, SET PARALLEL

COMBINATION OF R1 AND R2 ≤ 66.5k

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

3.3V OR

5V

REFER TO LTC1726-X OVERRIDE FUNCTIONS IN

THE APPLICATIONS INFORMATION SECTION

LTC1726-5

C

RT

10k

1

2

3

4

8

7

6

5

V

RT

CC3

CC5

CCA

C

WT

RST

WDI

R1*

ADJUSTABLE

SUPPLY

SYSTEM RESET

WDI

R2*

GND

1726 TA06

*TO PRESERVE THRESHOLD ACCURACY, SET PARALLEL

COMBINATION OF R1 AND R2 ≤ 66.5k

Dual Supply Monitor (3.3V Plus Adjustable)

Using V_CCATied to DC/DC Feedback Divider

2.9V

3.3V

35.7k

1%

LTC1726-2.5

C

LTC1435

V

LTC1726-5

C

RT

10k

RT

1

2

3

4

1

2

3

4

8

7

6

5

8

7

6

5

6

V

RT

WT

3.3V

V

RT

CC3

CC5

CCA

OSENSE

C

WT

2.8k

1%

5V

WT

RST

WDI

CC25

CCA

R1*

ADJUSTABLE

SUPPLY

SYSTEM RESET

WDI

SYSTEM RESET

WDI

RST

WDI

22.1k

1%

R2*

GND

ADJUSTABLE

RESET TRIP

THRESHOLD 2.74V

1726 TA07

1726 TA08

*TO PRESERVE THRESHOLD ACCURACY, SET PARALLEL

COMBINATION OF R1 AND R2 ≤ 66.5k

1726fd

10

For more information www.linear.com/LTC1726

LTC1726

package DescripTion

Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.

MS8 Package

8-Lead Plastic MSOP

(Reference LTC DWG # 05-08-1660 Rev F)

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)

0.889 ± 0.127

(.035 ± .005)

DETAIL “A”

0.254

(.010)

0° – 6° TYP

GAUGE PLANE

5.23

(.206)

MIN

1

2

3

4

3.20 – 3.45

(.126 – .136)

0.53 ± 0.152

(.021 ± .006)

1.10

(.043)

MAX

0.86

(.034)

REF

DETAIL “A”

0.18

(.007)

0.65

(.0256)

BSC

0.42 ± 0.038

(.0165 ± .0015)

SEATING

PLANE

TYP

0.22 – 0.38

0.1016 ± 0.0508

RECOMMENDED SOLDER PAD LAYOUT

(.009 – .015)

(.004 ± .002)

0.65

(.0256)

BSC

TYP

NOTE:

MSOP (MS8) 0307 REV F

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

1726fd

11

For more information www.linear.com/LTC1726

LTC1726

package DescripTion

Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.

S8 Package

8-Lead Plastic Small Outline (Narrow .150 Inch)

(Reference LTC DWG # 05-08-1610 Rev G)

.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)

4. PIN 1 CAN BE BEVEL EDGE OR A DIMPLE

SO8 REV G 0212

1726fd

12

For more information www.linear.com/LTC1726

LTC1726

revision hisTory ^{(Revision history begins at Rev C)}

REV

DATE

10/10 Added H-grade to Absolute Maximum Ratings and Electrical Characteristics sections.

4/13 Clarified ∆t conditions.

DESCRIPTION

PAGE NUMBER

C

2, 3

3

D

RT

1726fd

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.

13

For more information www.linear.com/LTC1726

LTC1726

Typical applicaTion

Triple Supply Monitor with Watchdog Timer and Manual Reset Button

12V ( 5ꢀ%

= 11.2V

V

TRIP

( 0.17V%

5V 3.3V

47nF

V

RT

CC3

CC5

CCA

100nF

47nF

LTC1726-5

R1

WT

RST

WDI

R3*

10k

5ꢀ

1.07M

100nF

0.1ꢀ

RESET

µP

R2

105k

0.1ꢀ

MANUAL

RESET BUTTON

(NORMALLY OPEN%

GND

I/O

1726 TA09

V

CCA

R2

V

=

(R1 + R2%

t

= 155ms

= 1s

*OPTIONAL RESISTOR RECOMMENDED

TO EXTEND ESD TOLERANCE

TRIP

RT

WT

V

TRIP

– 1

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

4.37V/4.62V Threshold

LTC1326

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

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

Precision Triple Supply Monitor for PCI Applications

Micropower Triple Supply Monitor with Individual Outputs

Micropower Triple Supply Monitor in 5-Pin SOT-23 Package

Micropower Triple Supply Monitor for 3V, 1.8V and ADJ

Quad Supply Monitor

4.725V, 3.118V, 1V Thresholds ( 0.75%) 5V, 3.3V, ADJ

2.363V, 3.118V, 1V Thresholds ( 0.75%) 2.5V, 3.3V, ADJ

LTC1326-2.5

LTC1536

Meets PCI t

Timing Specifications

FAIL

LTC1727-5

LTC1727-2.5

LTC1728-5

LTC1728-2.5

LTC1728-1.8

LTC1985-1.8

LTC2900

4.675V, 3.086V, 1V Thresholds ( 1.5%) 5V, 3.3V, ADJ

2.338V, 3.086V, 1V Thresholds ( 1.5%) 2.5V, 3.3V, ADJ

4.675V, 3.086V, 1V Thresholds ( 1.5%) 5V, 3.3V, ADJ

2.338V, 3.086V, 1V Thresholds ( 1.5%) 2.5V, 3.3V, ADJ

2.805V, 1.683V, 1V Thresholds ( 1.5%) 3V, 1.8V, ADJ

Push-Pull RESET Output, SOT-23

Adjustable Reset Timer

LTC2901

Quad Supply Monitor with Watchdog Timer

Adjustable Watchdog and Reset Timers

LTC2902

Quad Supply Monitor with Selectable Supply Tolerance

Precision Quad Supply Monitor in SOT-23

Reset Disable for Margining Applications

LTC2903

Fixed and Adjustable Threshold Combinations

8-Lead ThinSOT™ and 3mm × 2mm DFN Packages

8 Low Voltage Adjustable Inputs (0.5V)

LTC2908

Precision Six Supply Monitor

LTC2910

Octal Positive/Negative Voltage Monitor

1726fd

LT 0413 REV D • PRINTED IN USA

LinearTechnology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

14

For more information www.linear.com/LTC1726

(408)432-1900 FAX: (408) 434-0507 www.linear.com/LTC1726

●

 LINEAR TECHNOLOGY CORPORATION 2000


型号：	LTC1726ES8-5#PBF
厂家：	Linear
描述：	LTC1726 - Triple Supply Monitor and µP Supervisor with Adjustable Reset and Watchdog Timer; Package: SO; Pins: 8; Temperature Range: -40°C to 85°C 光电二极管
文件：	总14页 (文件大小：221K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LTC1726ES8-5#PBF [Linear]

相关型号：

LTC1726HMS8-5#PBF

LTC1726IS8-2.5

LTC1726IS8-2.5#PBF

LTC1726IS8-2.5#TR

LTC1726IS8-2.5#TRPBF

LTC1726IS8-5

LTC1726IS8-5#PBF

LTC1726IS8-5#TR

LTC1726_1

LTC1727

LTC1727

LTC1727-2.5