LTC2938CDE,LTC2938CDE pdf中文资料,LTC2938CDE引脚图,LTC2938CDE电路-Datasheet-电子工程世界

LTC2938/LTC2939

Conﬁgurable 4- and 6-Supply

Monitors with Watchdog Timer

FEATURES

n

DESCRIPTION

The LTC

®

2938/LTC2939 are conﬁgurable supply monitors

for systems with up to four or six supply voltages that need

watchdog supervision. One of sixteen preset or adjustable

voltage monitor combinations can be selected using an

external resistive divider connected to the program input.

The preset voltage thresholds are accurate to ±1.5% over

temperature. The LTC2938 and LTC2939 also feature ad-

justable inputs with a 0.5V nominal threshold.

The reset and watchdog timeout periods are adjustable

using external capacitors. Tight voltage threshold accuracy

and glitch immunity ensure reliable reset operation without

false triggering. The

RST

output is guaranteed to be in the

correct state for V

CC

down to 1V. Each status output has

a weak internal pull-up and may be externally pulled up

to a user-deﬁned voltage.

The 80μA supply current makes the LTC2938 and LTC2939

ideal for power conscious systems. The LTC2939 moni-

tors up to six supplies and the LTC2938 monitors up to

four supplies.

L,

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

Technology Corporation. All other trademarks are the property of their respective owners.

Protected by U.S. Patents, including 6967591, 7239251, 7119714.

n

Simultaneously Monitors Four (LTC2938) or Six

Supplies (LTC2939)

Sixteen User-Selectable Combinations of 5V, 3.3V,

2.5V, 1.8V, 1.5V, 1.2V and/or ± Adjustable Voltage

Thresholds

Guaranteed Threshold Accuracy: ±1.5%

Adjustable Reset and Watchdog Timeout

Low Supply Current: 80μA Typical

Power Supply Glitch Immunity

Guaranteed

RST

for V

CC

> 1V

High Temperature Operation to 125°C

12-Pin 4mm

×

3mm DFN or 12-Lead MSOP

(LTC2938) and 16-Lead MSOP Package (LTC2939)

APPLICATIONS

n

Desktop and Notebook Computers

Multivoltage Systems

Telecom Equipment

Network Servers

Automotive Control Systems

TYPICAL APPLICATION

6-Supply Monitor 12V (ADJ), 5V, 3.3V, 2.5V, 1.8V, 1.2V (ADJ)

12V

5V

3.3V

2.5V

1.8V

1.2V

2150k

1%

124k

1%

V1

V2

V3

V4

V5

V6

V

REF

Voltage Conﬁguration Table

V1 (V)

V2 (V)

3.3

2.5

1.8

2.5

1.8

1.5

1.2

V3 (V)

2.5

1.8

ADJ

1.8

1.5

1.2

ADJ

V4 (V)

1.8

ADJ

–

ADJ

1.5

ADJ

1.2

ADJ

–ADJ

ADJ

–ADJ

ADJ

V5 (V)

ADJ

V6 (V)

ADJ

293839ff

SYSTEM

LOGIC

0.1μF

WDI

LTC2939

WDO

RST

t

RST

= 94ms

t

WD

= 940ms

C

RT

47nF

293839 TA01

100k

1%

100k

1%

R1

59k

1%

R2

40.2k

1%

V

PG

GND

CWT

C

WT

47nF

CRT

5

3.3

1

LTC2938/LTC2939

ABSOLUTE MAXIMUM RATINGS

(Notes 1, 2, 3)

V1, V2, V3, V4, V5, V6, V

PG

......................... –0.3V to 7V

RST

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

CWT,

WDO

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

CRT, V

REF

, WDI ..............................–0.3V to (V

CC

+ 0.3V)

Reference Load Current (I

VREF

) ..............................±1mA

V4 Input Current (–ADJ Mode) ..............................–1mA

RST, WDO

Currents ............................................±10mA

Operating Temperature Range

LTC2939C..................................................... 0°C to 70°C

LTC2939I .................................................. –40°C to 85°C

LTC2939H .............................................. –40°C to 125°C

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

Lead Temperature (Soldering 10 sec)

MS Package Only .............................................. 300°C

PIN CONFIGURATION

LTC2938

V3

V1

CRT

RST

WDO

WDI

1

2

3

4

5

6

13

TOP VIEW

12 V2

11 V4

10 V

REF

9

8

7

V

PG

GND

CWT

MS PACKAGE

12-LEAD PLASTIC MSOP

T

JMAX

= 125°C,

θ

JA

= 130°C/W

V3

V1

CRT

RST

WDO

WDI

1

2

3

4

5

6

LTC2938

TOP VIEW

12

11

10

9

8

7

V2

V4

V

REF

V

PG

GND

CWT

V5

V3

V1

NC

CRT

RST

WDO

WDI

1

2

3

4

5

6

7

8

LTC2939

TOP VIEW

16

15

14

13

12

11

10

9

V6

V2

V4

NC

V

REF

V

PG

GND

CWT

DE PACKAGE

12-LEAD (4mm 3mm) PLASTIC DFN

T

JMAX

= 125°C,

θ

JA

= 43°C/W

EXPOSED PAD (PIN 13) PCB GND CONNECTION OPTIONAL

MS PACKAGE

16-LEAD PLASTIC MSOP

T

JMAX

= 125°C,

θ

JA

= 110°C/W

ORDER INFORMATION

LEAD FREE FINISH

LTC2938CDE#PBF

LTC2938IDE#PBF

LTC2938HDE#PBF

LTC2938CMS#PBF

LTC2938IMS#PBF

LTC2938HMS#PBF

LTC2939CMS#PBF

LTC2939IMS#PBF

LTC2939HMS#PBF

TAPE AND REEL

LTC2938CDE#TRPBF

LTC2938IDE#TRPBF

LTC2938HDE#TRPBF

LTC2938CMS#TRPBF

LTC2938IMS#TRPBF

LTC2938HMS#TRPBF

LTC2939CMS#TRPBF

LTC2939IMS#TRPBF

LTC2939HMS#TRPBF

PART MARKING*

2938

2939

PACKAGE DESCRIPTION

12-Lead (4mm

×

3mm) Plastic DFN

12-Lead (4mm

×

3mm) Plastic DFN

12-Lead (4mm

×

3mm) Plastic DFN

12-Lead Plastic MSOP

16-Lead Plastic MSOP

TEMPERATURE RANGE

0°C to 70°C

–40°C to 85°C

–40°C to 125°C

0°C to 70°C

–40°C to 85°C

–40°C to 125°C

0°C to 70°C

–40°C to 85°C

–40°C to 125°C

Consult LTC Marketing for parts speciﬁed with wider operating temperature ranges. *The temperature grade is identiﬁed by a label on the shipping container.

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/

293839ff

2

LTC2938/LTC2939

ELECTRICAL CHARACTERISTICS

SYMBOL

V

CC

V

CCMINP

V

RT50

V

RT33

V

RT25

V

RT18

V

RT15

V

RT12

V

RTA

V

RTAN

V

REF

V

PG

I

VPG

I

V1

I

V2

I

V3

I

V4

PARAMETER

Minimum Internal Operating Voltage

Minimum Required for Conﬁguration

5V, 5% Reset Threshold

3.3V, 5% Reset Threshold

2.5V, 5% Reset Threshold

1.8V, 5% Reset Threshold

1.5V, 5% Reset Threshold

1.2V, 5% Reset Threshold

ADJ Reset Threshold

–ADJ Reset Threshold

Reference Voltage

Conﬁguration Voltage Range

V

PG

Input Current

V1 Input Current

V2 Input Current

V3 Input Current

V4 Input Current

The

l

denotes the speciﬁcations which apply over the full operating

temperature range, otherwise speciﬁcations are at T

A

= 25°C, V

CC

= 5V unless otherwise speciﬁed. (Note 3)

CONDITIONS

RST

in Correct Logic State

V

CC

Rising

V1 Input Threshold

V1, V2 Input Threshold

V2, V3 Input Threshold

V2, V3, V4 Input Threshold

V3, V4, V5, V6 Input Threshold

V4 Input Threshold

V

CC

> 2.3V, I

VREF

= ±1mA,

C

REF

< 1000pF

V

CC

> V

CCMINP

V

PG

= V

REF

V1 = 5V, I

VREF

= 12μA, (Note 4)

V2 = 3.3V

V3 = 2.5V

V3 = 0.55V (ADJ Mode)

V4 = 1.8V

V4 = 0.55V (ADJ Mode)

V4 = -0.02V (–ADJ Mode)

V5, V6 = 0.55V

V

CRT

= GND

V

CRT

= 1.3V

C

RT

= 1500pF

V

n

Less Than Reset Threshold V

RTX

by

More Than 1%

I

SINK

= 2.5mA; V

CC

= 3V

I

SINK

= 100μA; V

CC

= 1V

I

SINK

= 2.5mA; V

CC

= 3.3V

I

SOURCE

= –1μA; V2 = 3.3V

V

CWT

= GND

V

CWT

= 1.3V

C

WT

= 1500pF

Logic Low

Open

Logic High

l

MIN

TYP

MAX

1

2.6

UNITS

V

mV

V

nA

μA

nA

μA

nA

μA

ms

μs

4.600

3.036

2.300

1.656

1.380

1.104

492.5

–18

1.192

0

4.675

3.086

2.338

1.683

1.403

1.122

500

0

1.210

4.750

3.135

2.375

1.710

1.425

1.140

507.5

18

1.228

V

REF

±20

80

0.8

0.52

0.34

125

2

1.2

±15

0.8

±15

–2.6

30

4

I

V5

, I

V6

I

CRT(UP)

I

CRT(DN)

t

RST

t

UV

V

OL

V

OL

V

OH

I

CWT(UP)

I

CWT(DN)

t

WD

V

WDI

V5, V6 Input Current (LTC2939)

CRT Pull-Up Current

CRT Pull-Down Current

Reset Timeout Period

V

n

Undervoltage Detect to

RST

Voltage Output Low

RST

Voltage Output Low

WDO

Voltage Output High

RST, WDO

(Note 5)

CWT Pull-Up Current

CWT Pull-Down Current

Watchdog Timeout Period

WDI Input Threshold

(V

CC

= 3.3V to 5.5V)

–1.4

10

2

–2

20

3

150

0.15

0.05

0.15

0.4

0.3

0.4

V

V2 – 1

–1.4

10

20

0.7

1.4

–2

20

30

0.9

–2.6

30

40

0.4

1.1

μA

ms

V

293839ff

3

LTC2938/LTC2939

ELECTRICAL CHARACTERISTICS

SYMBOL

I

WDI

PARAMETER

WDI Input Current

The

l

denotes the speciﬁcations which apply over the full operating

temperature range, otherwise speciﬁcations are at T

A

= 25°C, V

CC

= 5V unless otherwise speciﬁed. (Note 3)

CONDITIONS

V

WDI

= GND

V

WDI

= 0.7V

V

WDI

= 1.1V

V

WDI

= 5V

V

CC

= 3.3V or 5.5V

l

MIN

–10

10

2

TYP

MAX

–30

30

UNITS

μA

μs

t

WP

WDI Input Pulse Width

Note 1:

Stresses beyond those listed under Absolute Maximum Ratings

may cause permanent damage to the device. Exposure to any Absolute

Maximum Rating condition for extended periods may affect device

reliability and lifetime.

Note 2:

All currents into pins are positive, all voltages are referenced to

GND unless otherwise noted.

Note 3:

The greater of V1, V2 is the internal supply voltage (V

CC

).

Note 4:

Under static no-fault conditions, V1 will necessarily supply

quiescent current. If at any time V2 is larger than V1, V2 must be capable

of supplying the quiescent current, programming (transient) current and

reference load current.

Note 5:

The outputs

RST

and

WDO

have internal pull-ups to V2 of typically

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

times are required or for V

OH

voltages greater than V2. For V2 conﬁgured

to monitor 1.2V, 1.5V, 1.8V and 2.5V supplies, external pull-up resistors

are required to ensure that the output voltage, high, is above the V

IH

input

threshold of the external circuit.

TYPICAL PERFORMANCE CHARACTERISTICS

Normalized Threshold Voltages

vs Temperature

NORMALIZED THRESHOLD VOLTAGES (V/V)

1.015

1.010

1.005

1.000

0.995

0.990

0.985

–50 –25

THRESHOLD VOLTAGE, V

RTAN

(mV)

18

12

6

0

–6

–12

–18

–50 –25

V

REF

(V)

–ADJ Threshold Voltage

vs Temperature

1.228

1.222

1.216

1.210

1.204

1.198

V

REF

vs Temperature

50

25

75

0

TEMPERATURE (°C)

100

125

50

25

75

0

TEMPERATURE (°C)

100

125

1.192

–50 –25

50

25

75

0

TEMPERATURE (°C)

100

125

29389 G01

29389 G02

29389 G03

293839ff

4

LTC2938/LTC2939

TYPICAL PERFORMANCE CHARACTERISTICS

Supply Current vs Temperature

90

V1 = 5V

V2 = 3.3V

V3 = 2.5V

V4 = 1.8V

85

V5 = V6 = 1V

I

V4

(A)

–100μ

–10μ

–1μ

80

–100n

–10n

75

–1n

70

–50 –25

–100p

–300

25°C

125°C

TYPICAL TRANSIENT DURATION (μs)

I(V4) vs V4 in –ADJ mode

400

350

300

250

200

150

100

50

0

–250

–200

–150 –100

V4 (mV)

–50

0

29389 G05

Transient Duration

vs Comparator Overdrive

T

A

= 25°C

SUPPLY CURRENT, I

V1

(μA)

85°C

RESET OCCURS

ABOVE CURVE

50

25

75

0

TEMPERATURE (°C)

100

125

1

10

100

0.1

RESET COMPARATOR OVERDRIVE (% OF V

RTX

)

29389 G06

29389 G04

RST

Pull-Up Current vs V2

18

15

RST

OUTPUT VOLTAGE (V)

PULL-UP CURRENT (μA)

12

9

V

RT33

6

V

RT18

3

0

0.5

V

RT15

V

RT12

1

1.5

2

2.5 3

V2 (V)

3.5

4

4.5

5

V

RT25

T

A

= 25°C

6

RST

Output Voltage vs V1,

V

PG

= GND

WATCHDOG TIMEOUT PERIOD, t

WD

(ms)

T

A

= 25°C

10k PULL-UP FROM

RST

TO V1

5 V1 = V2

4

3

2

1

0

1

2

V1 (V)

29389 G07

29389 G08

Watchdog Timeout Period

vs Temperature

36

34

32

30

28

26

24

–50 –25

C

WT

= 1500pF

(SILVER MICA)

3

4

5

50

25

75

0

TEMPERATURE (°C)

100

125

29389 G09

Reset Timeout Period

vs Temperature

5

RESET TIMEOUT PERIOD, t

RST

(ms)

WATCHDOG TIMEOUT PERIOD t

WD

(s)

C

RT

= 1500pF

(SILVER MICA)

100

10

1

Watchdog Timeout Period vs C

WT

T

A

= 25°C

RESET TIMEOUT PERIOD t

RST

(s)

10

1

100m

10m

1m

100μ

Reset Timeout Period vs C

RT

T

A

= 25°C

4

3

100m

10m

1m

100μ

10p

2

1

–50

–25

75

0

25

50

TEMPERATURE (°C)

100

125

100p

1n

10n

C

WT

(F)

100n

1μ

29389 G11

10μ

10p

100p

1n

10n

C

RT

(F)

100n

1μ

29389 G12

29389 G10

293839ff

5

LTC2938CDE

LTC2938CDE概述

文档预览

推荐资源