LTC2995_技术文档

LTC2995

Temperature Sensor and

Dual Voltage Monitor with

Alert Outputs

FEATURES

DESCRIPTION

The LTC^®2995 is a high accuracy temperature sensor

and dual supply monitor. It converts the temperature of

an external diode sensor and/or its own die temperature

to an analog output voltage while rejecting errors due to

noise and series resistance. Two supply voltages and the

measured temperature are compared against upper and

lower limits set with resistive dividers. If a threshold is

exceeded, the device communicates an alert by pulling

low the correspondent open drain logic output.

n

Monitors Temperature and Two Voltages

n

Voltage Output Proportional to Temperature

n

Adjustable Thresholds for Temperature and Voltage

n

±±1° Remote Temperature Accuracy

n

±ꢀ1° ꢁnternal Temperature Accuracy

n

1.5% Voltage Threshold Accuracy

n

3.5ms Update Time

n

2.25V to 5.5V Supply Voltage

n

Input Glitch Rejection

n

Adjustable Reset Timeout

The LTC2995 gives 1°C accurate temperature results

using commonly available NPN or PNP transistors or

temperaturediodesbuiltintomoderndigitaldevices. Volt-

ages are monitored with 1.5% accuracy. A 1.8V reference

outputsimplifiesthresholdprogrammingandcanbeused

as an ADC reference input.

n

220μA Quiescent Current

n

Open Drain Alert Outputs

n

Available in 3mm × 3mm QFN Package

APPLICATIONS

TheLTC2995providesanaccurate, lowpowersolutionfor

temperature and voltage monitoring in a compact 3mm ×

3mm QFN package.

n

Network Servers

n

Core, I/O Voltage Monitors

n

Desktop and Notebook Computers

Environmental Monitoring

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.

n

TYPICAL APPLICATION

Dual OV/UV Supply and Single OT/UT Remote Temperature Monitor

V_PTATvs Remote

Diode Temperature

2.5V

1.2V

1.8

1.6

1.4

1.2

ASIC

+

–

V

D

CC

PS

470pF

0.1ꢀF

TEMPERATURE

SENSOR

DS

D

194k

10.2k

45.3k

VH1

LTC2995

VL1

VH2

VL2

4mV/K

V

1.0

0.8

PTAT

64.4k

10.2k

45.3k

OT T > 125°C

UT T < 75°C

+10%

SYSTEM

MONITOR

TO2

TO1

OV

75 100

125 150

REMOTE DIODE TEMPERATURE (°C)

–50 –25

0

25 50

–10%

2995 TA01b

UV

V

VT2

VT1

GND TMR

REF

20k

5nF

20k

140k

2995 TA01a

2995f

1

LTC2995

ABSOLUTE MAXIMUM RATINGS

PIN CONFIGURATION

(Notes ±, ꢀ)

V

.............................................................. –0.3V to 6V

CC

TOP VIEW

+

–

TMR, D , D , DS, PS, V

, V ........ –0.3V to V + 0.3V

PTAT REF

CC

UV, OV, TO1, T02 .......................................... –0.3V to 6V

VH1, VL1, VH2, VL2, VT1, VT2..................... –0.3V to 6V

Operating Ambient Temperature Range

LTC2995C................................................ 0°C to 70°C

LTC2995I .............................................–40°C to 85°C

LTC 2995H......................................... –40°C to 125°C

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

20 19 18 17 16

UV

15

14

13

12

11

VL1

VH2

VL2

VT2

VT1

1

2

3

4

5

OV

TO2

T01

21

8

V

REF

6

7

9 10

UD PACKAGE

20-LEAD (3mm × 3mm) PLASTIC QFN

T

= 150°C, θ = 59°C/W

JA

JMAX

EXPOSED PAD PCB GROUND CONNECTED OPTIONAL

ORDER INFORMATION

LEAD FREE FꢁNꢁSH

LTC2995CUD#PBF

LTC2995IUD#PBF

LTC2995HUD#PBF

TAPE AND REEL

PART MARKꢁNG*

LFQV

PA°KAGE DES°RꢁPTꢁON

TEMPERATURE RANGE

LTC2995CUD#TRPBF

LTC2995IUD#TRPBF

LTC2995HUD#TRPBF

0°C to 70°C

20-Lead (3mm × 3mm) Plastic QFN

LFQV

–40°C to 85°C

–40°C to 125°C

LFQV

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/

ELECTRICAL CHARACTERISTICS ^Thel denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at T_A= ꢀ51°, V_°°= 3.3V, unless otherwise noted.

SYMBOL

PARAMETER

°ONDꢁTꢁONS

MꢁN

2.25

1.7

TYP

MAX

5.5

UNꢁTS

l

V

Supply Voltage

V

CC

UVLO

Supply Undervoltage Lockout Threshold

Average Supply Current

V

CC

Falling

1.9

2.1

I

CC

220

300

ꢀA

Temperature Measurement

Reference Voltage

V

LTC2995

1.797

1.793

1.790

1.787

1.8

1.803

1.804

1.807

1.808

V

REF

l

LTC2995C

LTC2995I

LTC2995H

l

V

Load Regulation

I

=

LOAD

200μA

1.5

mV

ꢀA

REF

Remote Diode Sense Current

–8

–192

2995f

2

LTC2995

ELECTRICAL CHARACTERISTICS ^Thel denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at T_A= ꢀ51°, V_°°= 3.3V, unless otherwise noted.

SYMBOL

PARAMETER

°ONDꢁTꢁONS

MꢁN

TYP

3.5

4

MAX

UNꢁTS

ms

l

T

Temperature Update Interval

5

conv

K

V

Slope

mV/K

mV

Ideality Factor η = 1.004

T

PTAT

Load Regulation

I

=

200μA

1.5

1

LOAD

T

Internal Temperature Accuracy

0.5

2

°C

int

T

AMB

= –40°C to 125°C

0°C to 85°C (Notes 3, 4)

–40°C to 0°C (Notes 3, 4)

85°C to 125°C (Notes 3, 4)

0.25

1

1.5

°C

Remote Temperature Error, η = 1.004

RMT

Temperature Noise

0.15

0.01

°C

RMS

°C

/√Hz

°C/V

°C

RMS

l

T

Temperature Error vs Supply

0.5

1

VCC

RS

Series Resistance Cancellation Error

R

SERIES

= 100Ω

0.25

Temperature and Voltage Monitoring

l

V

Undervoltage/Overvoltage Threshold

VT1, VT2 Offset

492

–3

2

500

–1

5

508

1

mV

°C

UOT

OFF

T

ΔT

VT1, VT2 Temperature Hysteresis

UV, OV

10

2

°C

HYST

t

I

t

Input 5mV Above/Below Threshold

0.5

ms

nA

UOD

VH1, VL1, VH2, VL2, VT1, VT2, Input Current

UV/OV Time-Out-Period

20

IN

C

TMR

C

TMR

= TMR Open

= 1nF

0.5

10

ms

UOTO

l

5

20

I

TMR Current

2.5

ꢀA

TMR

Three State Pins DS, PS

l

V

PS, DS Input High Threshold

PS, DS Input Low Threshold

PS, DS High, Low Input Current

Allowable Leakage Current

V

– 0.4

V – 0.1

CC

V

DS,PS(H,TH)

DS,PS(H,TL)

DS,PS(IN,HL)

DS,PS(IN,Z)

CC

0.1

0.4

4

I

DS, PS at 0V or V

ꢀA

CC

1

Digital Outputs

l

V

OH

High Level Output Voltage,

TO1, TO2, UV, OV

I = –0.5μA

I = 3mA

– 1.2

CC

V

Low Level Output Voltage,

TO1, TO2, UV, OV

0.4

OL

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 3: Remote diode temperature, not LTC2995 temperature.

Note 4: Guaranteed by design and test correlation.

Note ꢀ: All currents into pins are positive; all voltages are referenced to

GND unless otherwise noted.

2995f

3

LTC2995

TIMING DIAGRAMS

VHn Monitor Timing

VLn Monitor Timing

V

VHn

V

VLn

UOT

t

UOTO

t

UOTO

UOD

UV

1V

OV

1V

2995 TD01

2995 TD02

VHn Monitor Timing (TMR Pin Strapped to V_°°

)

VLn Monitor Timing (TMR Pin Strapped to V_°°

)

V

UOT

VHn

VLn

UOT

t

UOD

UV

1V

OV

1V

2995 TD03

2995 TD04

2995f

4

LTC2995

T_A= ꢀ51°, V_°°= 3.3V unless otherwise noted.

TYPICAL PERFORMANCE CHARACTERISTICS

Remote Temperature Error

vs Ambient Temperature

ꢁnternal Temperature Error

vs Ambient Temperature

Temperature Error with LT°ꢀ995 at

Same Temperature as Remote Diode

3

2

3

2

3

2

T

= T

REMOTE

T

= 25°C

INTERNAL

REMOTE

1

0

–1

–2

–3

–1

–2

–3

–1

–2

–3

–50 –25

0

25 50 75 100 125 150

–50 –25

0

25 50 75 100 125 150

(°C)

–50 –25

0

25 50 75 100 125 150

(°C)

T

(°C)

T

A

T

A

2995 G01

2995 G02

2995 G03

Temperature Error vs Supply

Voltage

Remote Temperature Error

vs °_DE°OUPLE(Between D⁺and D^–)

Remote Temperature Error

vs Series Resistance

0.6

0.4

0.2

0

6

4

6

4

2

0

2

0

–0.2

–0.4

–2

–4

–6

–2

–4

–6

–0.6

6

2

3

4

5

0

200

400

600

800 1000 1200

0

2

4

6

8

10

V

(V)

SERIES RESISTANCE (Ω)

DECOUPLE CAPACITOR (nF)

CC

2995 G04

2995 G05

2995 G06

UVLO vs Temperature

V_°°Rising, Falling

Buffered Reference Voltage

vs Temperature

V_PTATNoise vs Averaging Time

0.20

0.15

0.10

0.05

0

2.2

2.0

1.8

1.6

1.810

1.805

1.800

1.795

1.790

V

CC

RISING

FALLING

CC

V

10

AVERAGING TIME (ms)

100

1000

0.01

0.1

1

100 125 150

–50 –25

0

25 50 75

(°C)

100 125 150

–50 –25

0

25 50 75

(°C)

T

A

2995 G07

2995 G08

2995 G09

2995f

5

LTC2995

TYPICAL PERFORMANCE CHARACTERISTICS T_A= ꢀ51°, V_°°= 3.3V unless otherwise noted.

Load Regulation of V_REF

Voltage vs °urrent

–

Single Wire Remote Temperature

Error vs Ground Noise

Load Regulation of V_PTAT

Voltage vs °urrent

–

10

1

1.82

1.81

1.80

1.79

1.78

1.22

1.20

1.18

1.16

1.14

V

= 2.25V

= 3.5V

= 4.5V

= 5.5V

V

= 2.25V

= 3.5V

= 4.5V

= 5.5V

CC

VAC = 50mV

P-P

V

CC

V

CC

V

CC

0.1

0.01

2

4

100

1000

–4

–2

0

2

4

–4

–2

0

0.1

1

10

FREQUENCY (kHz)

LOAD CURRENT (mA)

2995 G10

2995 G11

2995 G12

UV, OV, TO1, TO2 vs Output Sink

°urrent

Delay vs °omparator Overdrive

1

1200

1000

800

600

400

200

0

0.8

0.6

0.4

0.2

0

35

100

0

5

10

15

20

25

30

1

10

I (mA)

OVERDRIVE (mV)

2995 G14

2995 G13

Reset Timeout Period

vs °apacitance

Supply °urrent vs Temperature

10000

1000

100

10

250

240

230

220

210

200

1

75

100 125 150

1000

–50 –25

0

25 50

(°C)

0.1

1

10

100

T

TMR PIN CAPACITANCE (nF)

A

2995 G16

2995 G15

2995f

6

LTC2995

PIN FUNCTIONS

+

D : Diode Sense Current Source. D sources the remote

TO1: Temperature Logic Output 1. Open drain logic output

+

diode sensing current. Connect D to the anode of the re-

thatpullstoGNDwhenV

crossesthethresholdvoltage

PTAT

motesensordevice.Itisrecommendedtoconnecta470pF

on pin VT1 with a polarity set by the PS pin (see Table 3

in Applications Information). When V crosses the

+

–

bypass capacitor between D and D . Larger capacitors

PTAT

may cause settling time errors (see Typical Performance

threshold voltage on pin VT1 with opposite polarity, an

additional hysteresis of 20mV is required to release TO1

high after a delay adjustable by the capacitor on TMR. TO1

+

Characteristics).IfD is tied to V ,theLTC2995measures

CC

+

the internal sensor temperature. Tie D to V if unused.

CC

has a weak 400kΩ pull-up to V and may be pulled above

–

CC

D : Diode Sense Current Sink. Connect D to the cathode

V

CC

using an external pull-up. Leave TO1 open if unused.

–

of the remote sensor device. Tie D to GND for single

wire remote temperature measurement (see Applications

Information) or internal temperature sensing.

TO2: Temperature Logic Output 2. Open drain logic output

thatpullstoGNDwhenV crossesthethresholdvoltage

PTAT

on pin VT2 with a polarity set by the PS pin (see Table 3

in Applications Information). When V crosses the

DS: Diode Select Input. Three state pin that selects tem-

PTAT

perature sensor location. Tie DS to V to monitor the

CC

threshold voltage on pin VT2 with opposite polarity, an

additional hysteresis of 20mV is required to release TO2

high after a delay adjustable by the capacitor on TMR. TO2

temperature of the internal diode or to GND to monitor the

temperature of the external diode. When DS is left uncon-

nected, the LTC2995 monitors both sensors alternately.

has a weak 400kΩ pull-up to V and may be pulled above

+

CC

If D is tied to V , the LTC2995 measures the internal

CC

V

CC

using an external pull-up. Leave TO2 open if unused.

sensor temperature regardless of the state of DS.

UV: Undervoltage Logic Output. Open drain logic output

that pulls to GND when either the voltage at VH1 or VH2

is below 0.5V. Held low for an adjustable delay time set

by the capacitor connected to pin TMR. UV has a weak

Exposed Pad: Exposed pad may be left open or soldered

to GND for better thermal coupling.

GND: Device Ground

400kΩ pull-up to V and may be pulled above V using

CC

OV: Overvoltage Logic Output. Open drain logic output

that pulls to GND when either the voltage at VL1 or VL2

is above 0.5V. Held low for a programmable delay time

set by the capacitor connected to pin TMR. OV has a weak

an external pull-up. Leave pin open if unused.

V : Supply Voltage. Bypass this pin to GND with a 0.1μF

°°

(or greater) capacitor. V operatingrangeis2.25Vto5.5V.

CC

400kΩ pull-up to V and may be pulled above V using

CC

VH±, VHꢀ: Voltage High Inputs 1 and 2. When the voltage

an external pull-up. Leave OV open if unused.

on either pin is below 0.5V, an undervoltage condition is

PS: Polarity Select Input. Selects the polarity of tempera-

triggered. Tie pin to V if unused.

CC

turethresholdsVT1andVT2.ConnectPStoV toconfig-

CC

VL±, VLꢀ: Voltage Low Inputs 1 and 2. When the voltage

on either pin is above 0.5V, an overvoltage condition is

triggered. Tie pin to GND if unused.

ureVT1asundertemperatureandVT2asovertemperature

threshold. Leave PS unconnected to configure both VT1

and VT2 as overtemperature thresholds. Connect PS to

GND to configure both VT1 and VT2 as undertemperature

V

: Proportional to Absolute Temperature Voltage

PTAT

thresholds.TietoV iftemperaturethresholdsareunused.

Output. The voltage on this pin is proportional to the

CC

selected sensor’s absolute temperature. An internal or

external sensor is chosen with the DS pin. V

TMR: Reset Delay Timer. Attach an external capacitor

(CTMR) to GND to set the delay time until alerts on TO1,

TO2, UV and OV are reset. Leaving the pin open generates

a minimum delay of 500μs. Capacitance on this pin adds

can

PTAT

drive up to 200μA of load current and up to 1000pF of

capacitive load. For larger load capacitances insert a 1k

an additional 8ms/nF reset delay time. Tie TMR to V to

CC

bypass the timer.

2995f

7

LTC2995

PIN FUNCTIONS

resistor between V

and the load to ensure stability.

VT±: Temperature Threshold 1. When V

crosses the

PTAT

V

is pulled low when the supply voltage goes below

voltage on VT1 with a polarity set by the PS pin, TO1 is

PTAT

the under voltage lockout threshold.

pulled low. Tie VT1 to GND if unused.

V

: Voltage Reference Output. V

provides a 1.8V

VTꢀ: Temperature Threshold 2. When V

crosses the

REF

PTAT

reference voltage. V

can drive up to 200μA of load

voltage on VT2 with a polarity set by the PS pin, TO2 is

REF

current and up to 1000pF of capacitive load. For larger

load capacitances insert 1kΩ between V

to ensure stability. Leave V

pulled low. Tie VT2 to V if unused.

CC

and the load

REF

open if unused.

REF

BLOCK DIAGRAM

9

16

V

CC

TMR

V

CC

400k

VH1

20

–

CH1

UV

15

UV PULSE

GENERATOR

+

–

CL1

OSCILLATOR

VL1

VH2

+

2V

V

+

–

1

2

UVLO

–

V

CC

CH2

CC

400k

OV

+

14

–

+

CL2

OV PULSE

GENERATOR

200kΩ

VL2

3

+

–

1.2V

V

1.8V

REF

11

1.3MΩ

200k

0.5V

500k

V

CC

400k

TO2

–

VT2

CT2

13

4

TO1/TO2

PULSE

GENERATOR

+

UVLO

V

CC

400k

TO1

–

+

CT1

12

VT1

5

8

3 STATE

DECODE

T TO V

CONVERTER

V

PTAT

1

3 STATE

DECODE

–

+

DS

D

PS

19

GND

18

7

6

17

2995 BD

2995f

8

LTC2995

OPERATION

Overview

on the process depended variable I . Measuring the same

S

diode (with the same value I ) at two different currents

S

The LTC2995 combines the functionality of a temperature

measurement and monitor device with a dual voltage

supervisor. It provides a buffered voltage proportional to

the absolute temperature of either an internal or a remote

(I and I ) yields an expression independent of I :

D1

D2

S

q

η t k

V – V

D2

D1

T =

t

I

⎛

⎞

D2

diode(V

)andcomparesthisvoltagetothresholdsthat

ln

PTAT

⎜

⎝

⎟

⎠

I

D1

can be set by external resistor dividers from the on-board

reference (V ).

REF

Series Resistance °ancellation

The LTC2995 also provides four voltage threshold

inputs that are continuously compared to an internal 0.5V

reference allowing two systems voltages to be monitored

for undervoltage and overvoltage conditions.

Resistanceinserieswiththeremotediodecausesapositive

temperature error by increasing the measured voltage at

each test current. The composite voltage equals:

Diode Temperature Sensor

I

kT

= η t ln

q

⎛ ⎞

D

V + V

+ R tI

S D

⎜ ⎟

D

ERROR

⎝ ⎠

I

Temperature measurements are conducted by measuring

the voltage of either an internal or an external diode with

multiple test currents. The relationship between diode

voltage V and diode current I can be solved for absolute

S

The LTC2995 removes this error term from the sensor

signal by subtracting a cancellation voltage V . A

resistance extraction circuit uses one additional current

measurement to determine the series resistance in the

measurementpath.Oncethecorrectvalueoftheresistoris

D

CANCEL

Temperature in degrees Kelvin T:

q

η t k

V

D

T =

t

I

⎛ ⎞

D

determined,V

equalsV

.Nowthetemperature

CANCEL

ERROR

ln

⎜ ⎟

⎝ ⎠

I

to voltage converter input signal is free from errors due

to series resistance.

S

where I is a process dependent factor on the order of

S

LTC2995cancancelseriesresistancesupseveralhundred

ohms (see Typical Performance Characteristics curves).

Higher series resistances cause the cancelation voltage

to saturate.

–13

10 A, η is the diode ideality factor, k is the Boltzmann

constantandqistheelectroncharge.Thisequationshows

arelationshipbetweentemperatureandvoltagedependent

2995f

9

LTC2995

APPLICATIONS INFORMATION

Temperature Measurements

°hoosing an External Sensor

The LTC2995 continuously measures the sensor diode at

differenttestcurrentsandgeneratesavoltageproportional

The LTC2995 is factory calibrated for an ideality factor of

1.004, which is typical of the popular MMBT3904 NPN

transistor. Semiconductor purity and wafer level process-

ing intrinsically limit device-to-device variation, making

these devices interchangeable between manufacturers

withatemperatureerroroftypicallylessthan0.5°C.Some

recommended sources are listed in Table 2:

to the absolute temperature of the sensor at the V

pin.

PTAT

The voltage at V

is updated every 3.5ms.

PTAT

The gain of V

is calibrated to 4mV/K for the measure-

PTAT

ment of the internal diode as well as for remote diodes

with an ideality factor of 1.004.

Table ꢀ Recommended Transistors for Use As Temperature

Sensors

V

PTAT

T_KELVIN

=

(η = 1.004)

MANUFA°TURER

PART NUMBER

PA°KAGE

4mV/K

Fairchild

Semiconductor

MMBT3904

SOT-23

If an external sensor with an ideality factor different from

1.004 is used, the gain of V

will be scaled by the ratio

Central

Semiconductor

CMBT3904

SOT-23

PTAT

oftheactualidealityfactor(η )to1.004. Inthesecases,

ACT

Diodes Inc.

On Semiconductor

NXP

MMBT3904

MMBT3904LT1

MMBT3904

UMT3904

SOT-23

SC-70

the temperature of the external sensor can be calculated

from V

by:

PAT

V

1.004

PTAT

Infineon

T_KELVIN

=

•

4mV/K

η

Rohm

ACT

Discrete two terminal diodes are not recommended as

remote sensing devices as their ideality factor is typically

much higher than 1.004. Also MOS transistors are not

suitable as they don’t exhibit the required current to tem-

peraturerelationship. Furthermoregolddopedtransistors

(low beta), high frequency and high voltage transistors

should be avoided as remote sensing devices.

Temperature in degrees Celsius can be deduced from

degrees Kelvin by:

T

= T

– 273.15

KELVIN

CELSIUS

The three-state diode select pin (DS) determines whether

the temperature of the external or the internal diode is

measured and displayed at V

as described in Table 1.

PTAT

Table ±. Diode Selection

°onnecting an External Sensor

DꢁODE LO°ATꢁON

Internal

DS PꢁN

The change in sensor voltage per °C is hundreds of

microvolts, so electrical noise must be kept to a mini-

V

CC

External

GND

+

–

mum. Bypass D and D with a 470pF capacitor close to

the LTC2995 to suppress external noise. Recommended

shielding and PCB trace considerations for best noise

immunity are illustrated in Figure 1.

Both

Open

If the DS pin is left open, the LTC2995 measures both

diodesalternatelyandV

changesevery30msfromthe

PTAT

GND SHIELD TRACE

voltage corresponding to the temperature of the internal

LTC2995

+

sensor to the voltage corresponding to the temperature

D

470pF

+

–

D

of the external sensor. If D is tied to V , the LTC2995

CC

GND

measures the internal diode regardless of the state of

2995 F01

NPN SENSOR

the DS pin.

Figure ±. Recommended P°B Layout

2995f

10

LTC2995

APPLICATIONS INFORMATION

Leakage currents at D affect the precision of the remote

temperature measurements. 100nA leakage current leads

to an additional error of 2°C (see Typical Performance

Characteristics).

+

components.Noisearoundoddmultiplesof6kHz( 20%)is

amplified by the measurement algorithm and converted at

a DC offset in the temperature measurement (see Typical

Performance Characteristics).

Note that bypass capacitors greater than 1nF will cause

settling time errors in the different measurement cur-

rents and therefore introduce an error in the temperature

measurement (see Typical Performance Characteristics).

The LTC2995 can withstand up to 4kV of electrostatic

discharge (ESD, human body). ESD beyond this voltage

can damage or degrade the device including lowering the

remote sensor measurement accuracy due to increased

+

–

leakage currents on D or D .

The LTC2995 compensates series resistance in the

measurement path and thereby allows accurate remote

temperature measurements even with several meters of

distance between the sensor and the device. The cable

lengthbetweenthesensorandtheLTC2995isonlylimited

To protect the sensing inputs against larger ESD strikes,

external protection can be added using TVS diodes to

ground (Figure 3). Care must be taken to choose diodes

with low capacitance and low leakage currents in order

nottodegradetheexternalsensormeasurementaccuracy

(see Typical Performance Characteristics curves).

+

by the mutual capacitance introduced between D and

–

D which degrades measurement accuracy (see Typical

Performance Characteristics).

LTC2995

10Ω

For example an AT6 cable with 50pF/m should be kept

shorter than ~20m to keep the capacitance less than 1nF.

+

D

MMBT3904

220pF

–

To save wiring, the cathode of the remote sensor can

GND

–

2995 F03

PESD5Z6.0

also be connected to remote GND and D to local GND

as shown below.

Figure 3. ꢁncreasing ESD Robustness with TVS Diodes

LTC2995

+

D

470pF

2N3904

–

To make the connection of the cable to the IC polarity

insensitive during installation, two sensor transistors

with opposite polarity at the end of a two wire cable can

be used as shown on Figure 4.

D

GND

2995 F02

Figure ꢀ. Single Wire Remote Temperature Sensing

LTC2995

+

The temperature measurement of the LTC2995 relies only

on differences between the diode voltage at multiple test

circuits.ThereforeDCoffsetssmallerthan300mVbetween

remote and local GND do not impact the precision of the

temperature measurement. The cathode of the sensor

can accommodate modest ground shifts across a system

which is beneficial in applications where a good thermal

connectivity of the sensor to a device whose temperature

is to be monitored (shunt resistor, coil, etc.) is required.

Care must be taken if the potential difference between

D

MMBT3904

470pF

–

D

GND

2995 F04

Figure 4. Polarity ꢁnsensitive Remote Diode Sensor

Again, care must be taken that the leakage current of the

second transistor does not degrade the measurement

accuracy.

–

the cathode and D does not only content DC but also AC

2995f

11

LTC2995

APPLICATIONS INFORMATION

Output Noise Filtering

pulledlowifthevoltageV

fallsduringfiveconsecutive

PTAT

conversions below the undertemperature threshold VT1.

Once pulled low, TO1 is released high again if V rises

The V

output typically exhibits 0.6mV RMS (0.25°C

PTAT

RMS) noise. For applications which require lower noise

digital or analog averaging can be applied to the output.

Choose the averaging time according to:

above VT1 plus an additional hysteresis of about 20mV.

Accordingly, T02 is pulled low if the voltage V rises

PTAT

abovetheovertemperaturethresholdVT2and–oncepulled

2

low– TO2 is released high if V falls below VT2 minus

⎛

⎜

⎝

⎞

PTAT

[

]

°

0.01 C Hz

anadditionalhysteresisofabout20mV.LeavingPSuncon-

nected configures both VT1 and VT2 as overtemperature

thresholds and connecting PS to GND configures them

both as undertemperature thresholds. If the internal and

external sensors are monitored alternately by leaving DS

unconnected, VT1 becomes a dedicated threshold for the

internal sensor and VT2 becomes a dedicated threshold

for the external sensor.

⎟

⎠

t_AVG

=

T

NOISE

where t

is the averaging time and T

the desired

NOISE

AVG

temperature noise in °C RMS. For example, if the desired

noiseperformanceis0.015°CRMS,settheaveragingtime

to one second. See Typical Performance Characteristics.

Temperature Monitoring

Temperature Monitor Design Example

The LTC2995 continuously compares the voltage at V

PTAT

The LTC2995 can be configured to give an early warning

if the temperature of the internal sensor rises above 60°C

and an alarm if the temperature passes 90°C. Tie the DS

to the voltages at the pins VT1 and VT2 to detect either an

overtemperature(OT)orundertemperature(UT)condition.

The VT1 comparator output drives the open-drain logic

output pin TO1 and the VT2 comparator output drives the

open-drain logic output pin TO2. The polarity of these

comparisons is configured via the three-state polarity

select pin (PS) (Table 3).

pin to V to select the internal sensor and leave the pin

CC

PS unconnected to configure both input voltages VT1 and

VT2 as overtemperature thresholds. The voltages at VT1

and VT2 are set to:

mV

K

Table 3. Temperature Polarity Selection

VT1 =(60K + 273.15K) • 4

= 1.332V

= 1.452V

PS PꢁN

FUN°TꢁON

°ONDꢁTꢁON OUTPUT

VT1 Undertemperature

Threshold

mV

K

V

PTAT

V

PTAT

V

PTAT

V

PTAT

V

PTAT

V

PTAT

< VT1 TO1 Pulled Low

> VT2 TO2 Pulled Low

> VT1 TO1 Pulled Low

> VT2 TO2 Pulled Low

< VT1 TO1 Pulled Low

< VT2 TO2 Pulled Low

VT2 =(90K + 273.15K) • 4

V

CC

VT2 Overtemperature

Threshold

WhenV

reachesthethresholdvoltageonpinVT1,TO1

PTAT

VT1 Overtemperature

Threshold

is pulled low indicating an overtemperature early warning.

If the temperature reaches 90°C TO2 is also pulled low,

indicating an overtemperature alarm.

Open

GND

VT2 Overtemperature

Threshold

VT1 Undertemperature

Threshold

Once the temperature drops below each threshold, the

corresponding TO pins will return high after a time-out-

VT2 Undertemperature

Threshold

period (t

) set by the capacitor connected to TMR.

UOTO

If pin PS is connected to V , the voltage on VT1 becomes

CC

an undertemperature threshold and the voltage on VT2

an overtemperature threshold. In this configurationTO1 is

2995f

12

LTC2995

APPLICATIONS INFORMATION

Temperature Thresholds

The following design procedure can be used to size the

resistive divider.

The threshold voltages at VT1 and VT2 can be set with

the 1.8V reference voltage (V ) and a resistive divider

1. Calculate Threshold Voltages:

REF

as shown in Figure 5.

mV

K

η

ACT

1.004

VT1 = T1• 4

•

η

mV

K

V

REF

= 1.8V

V

ACT

PTAT

SLOPE =

tꢀꢁꢀ

ꢂꢃꢄꢄꢁ

mV

K

η

ACT

1.004

VT2 = T2 • 4

•

1.8V

VT2

R

TC

R

where η denotes the actual ideality factor if an external

TB

ACT

VT1

sensor is used and T1 and T2 are the desired threshold

O.8V

temperatures in degrees Kelvin.

R

TA

2. Choose R to obtain the desired VT1 threshold for

TA

T

a desired current through the resistive divider

2995 F05

O

200k

T

1

T

ꢁꢅꢄL

2

(I ):

REF

Figure 5. Temperature Thresholds

VT1

R

=

TA

I

REF

3. Choose R to obtain the desired VT2 threshold:

TB

VT2 – VT1

R

=

TB

I

REF

3.3V

+

D

DS

V

PS

LTC2995

CC

V

CC

V

CC

400k

TO2

+

1.2V

1.8V

V

REF

–

OT ALARM

200k

400k

R

TC

V

CC

VT2

VT1

–

+

400k

TO1

TO1/TO2

PULSE

GENERATOR

UVLO

R

TB

OT WARNING

–

+

V

PTAT

T/V

TA

–

D

GND

2995 F06

Figure 6. Monitoring ꢁnternal Temperature with Two Overtemperature Thresholds

2995f

13

LTC2995

APPLICATIONS INFORMATION

V

4. Finally R is determined by:

n

TC

LTC2995

1.8V – VT2

R

C

B

R

=

V

–

+

Hn

TC

I

REF

UV

OV

n

IntheTemperatureMonitorexamplediscussedearlierwith

thresholds at VT1 = 60°C and VT2 = 90°C and a desired

+

–

0.5V

reference current of 10μA, the required values for R ,

TA

–

+

R

and R can be calculated as:

TB

TC

n

V

Ln

1.332V

10ꢀA

R

=

= 133.2k

TA

TB

TC

R

A

2995 F07

1.452V – 1.332V

10ꢀA

Figure 7. 3-Resistor Positive UV/OV Monitoring

R

= 12k

For supply monitoring, V is the desired nominal operat-

n

ing voltage, I is the desired nominal current through the

n

1.8V – 1.452V

resistive divider, V is the desired overvoltage trip point,

= 34.8k

OV

10ꢀA

and V is the desired undervoltage trip point.

UV

1. R is chosen to set the desired trip point for the

A

Voltage Monitoring

overvoltage monitor:

In addition to temperature measurement, the LTC2995

features a low power dual voltage monitoring circuit. Each

voltage monitor has two inputs (VH1/VL1 and VH2/VL2)

for detecting undervoltage and overvoltage conditions. If

either VH1 or VH2 falls below 0.5V (typical), the LTC2995

communicates an undervoltage condition by pulling UV

low. Similar, an overvoltage condition is flagged by pulling

OV low if either VL1 or VL2 rises above 0.5V.

0.5V

V

N

R =

•

(1)

A

I

V

N

OV

2. Once R is known, R is chosen to set the desired

A

B

trip point for the undervoltage monitor:

0.5V

V

N

R =

•

– R

(2)

B

A

I

V

UV

N

When configured to monitor a positive voltage Vn using

the 3-resistor circuit configuration shown in Figure 5,

3. Once, R and R are known, R is determined by:

A

B

C

V

will be connected to the high side tap of the resistive

Hn

V

divider and V will be connected to the low side tap of

N

Ln

R =

– R – R

(3)

C

A

B

the resistive divider.

I

N

Voltage Monitor Design Procedure

Voltage Monitor Example

Thefollowing3-stepdesignprocedureselectsappropriate

resistances to obtain the desired UV and OV trip points

for the voltage monitor circuit in Figure 7.

A typical voltage monitor application is shown in Figure 2.

The monitored voltage is a 5V 10% supply. Nominal

current in the resistive divider is 10ꢀA.

1. Find R to set the OV trip point of the monitor:

A

0.5V 5V

10ꢀA 5.5V

R =

•

≈ 45.3k

A

2995f

14

LTC2995

APPLICATIONS INFORMATION

The two extreme conditions, with a relative accuracy of

1.5% and resistance accuracy of 1%, result in:

2. Find R to set the UV trip point of the monitor:

B

0.5V 5V

10ꢀA 4.5V

R =

•

– 453 ≅ 10k

B

⎛

⎞

⎟

R t 0.99

C

V

= 0.5V t 0.985 t 1+

⎜

UV(MIN)

(R + R ) t 1.01

⎠

⎝

A

B

3. Determine R to complete the design:

C

and

5V

10ꢀA

R =

– 453Ω – 100Ω ≈ 442k

⎛

⎞

C

R t 1.01

C

V

= 0.5V t 1.015 t 1+

⎜

⎟

UV(MAX)

(R + R ) t 0.99

⎠

⎝

A

B

Power-Up and Undervoltage Lockout

R

C

= 8

As soon as V reaches approximately 1V during

For a desired trip point of 4.5V,

Therefore,

CC

R + R

A

B

power-up,theOV aswellasTO1 andTO2 weakly pull to V

CC

while the UV output asserts low indicating an undervolt-

⎛

⎞

0.99

1.01

age lockout condition. Above V = 2V (typical), the VH

CC

V

= 0.5V t 0.985 t 1+ 8

= 4.3545V

= 4.650V

⎜

⎟

UV(MIN)

and VL inputs take control. Once both VH inputs and V

⎠

⎝

CC

are valid, an internal timer is started. After an adjustable

delay time, UV weakly pulls high.

and

⎛

⎞

1.01

0.99

When V falls below 1.9V, the LTC2995 indicates again

CC

V

= 0.5V t 1.015 t 1+ 8

⎜

⎟

UV(MAX)

an undervoltage lockout (UVLO) condition by pulling low

⎠

⎝

UV while OV is cleared.

Glitch ꢁmmunity

Threshold Accuracy

In any supervisory application, noise on the monitored DC

voltage can cause spurious resets. To solve this problem

withoutaddinghysteresistotheVH/VLcomparators,which

would add error to the trip voltage, the LTC2995 lowpass

filters the output of the comparator. This filter causes the

output of the comparator to be integrated before assert-

ing the UV or OV logic. Any transient at the input of the

comparator must be of sufficient magnitude and duration

before the comparator will trigger the output logic. The

TypicalPerformanceCharacteristicssectionshowsagraph

oftheTypicalTransientDurationvsComparatorOverdrive.

Resetthresholdaccuracyisimportantinasupplysensitive

system. Ideally, such a system would only reset if supply

voltages fell outside the exact threshold for a specified

margin. All LTC2995 VHn/VLn inputs have a relative

threshold accuracy of 1.5% over the full operating

temperature range. For example, when the LTC2995 is

configured to monitor a 5V input with a 10% tolerance,

the desired UV trip point is 4.5V. Because of the 1.5%

relative accuracy of the LTC2995, the UV trip point can be

anywherebetween4.433Vand4.567Vwhichis4.5V 1.5%.

Likewise, the accuracy of the resistances chosen for R ,

A

In temperature monitoring, the voltage at V

must

PTAT

R , and R can affect the UV and OV trip points as well.

B

C

exceed a threshold for five consecutive temperature up-

Using the previous example, if the resistances used to set

the UV trip point have 1% accuracy, the UV trip range can

grow to between 4.354V and 4.650V. This is illustrated in

the following calculations.

date intervals before the respective TO pin is pulled low.

Once the V

voltage crosses back the threshold with

PTAT

an additional 20mV of hysteresis, the respective TO pin

is released after a single update interval and an additional

delay adjustable by the capacitor on TMR.

The UV trip point is given as:

⎛

⎞

⎟

⎠

R

C

V

= 0.5V t 1+

⎜

UV

R + R

⎝

A

B

2995f

15

LTC2995

APPLICATIONS INFORMATION

Timing of Alert Outputs

Digital Output °haracteristics

The LTC2995 has an adjustable timeout period (t

)

The DC characteristics of the UV, OV, TO1 and TO2 pull-up

and pull-down strength are shown in the Typical Perfor-

manceCharacteristicssection.Eachpinhasaweak400kΩ

UOTO

that holds UV, OV, TO1 or TO2 asserted after any faults

have cleared. This delay will minimize the effect of input

noise with a frequency above 1/t

.

internal pull-up to V and a strong pull-down to ground

UOTO

CC

and can be pulled above V .

CC

A voltage monitoring example: When any VH drops below

its threshold, the UV pin asserts low. When all VH inputs

recover above their thresholds, the output timer starts. If

all inputs remain above their thresholds when the timer

finishes, the UV pin weakly pulls high. However, if any

input falls below its threshold during this timeout period,

the timer resets and restarts when all inputs are again

above the thresholds.

This arrangement allows these pins to have open-drain

behavior while possessing several other beneficial char-

acteristics. The weak pull-up eliminates the need for an

external pull-up resistor when the rise time on the pin is

notcritical.Ontheotherhand,theopendrainconfiguration

allows for wired-OR connections and can be useful when

more than one signal needs to pull-down on the output.

A temperature monitoring example: Tying PS to V

At V = 1V, the weak pull-up current is barely turned on.

CC

configures TO2 as overtemperature output. In case of

an overtemperature condition pin TO2 asserts low. The

output timer starts when the temperature crosses back

below the threshold minus the temperature hysteresis If

the temperature remains below the threshold, the timer

finishes and pin TO2 releases high.

Therefore, an external pull-up resistor of no more than

100k is recommended on the pin if the state and pull-up

strength of the pin is crucial at very low V .

CC

Note however, by adding an external pull-up resistor, the

pull-up strength on the pin is increased. Therefore, if it

is connected in a wired-OR connection, the pull-down

strength of any single device needs to accommodate this

additional pull-up strength.

Selecting the Timing °apacitor

Thetimeoutperiod(t )fortheLTC2995isadjustablein

UOTO

order to accommodate a variety of applications. Connect-

ing a capacitor, C , between the TMR pin and ground

Output Rise and Fall Time Estimation

TMR

The UV, OV, TO1 and TO2 outputs have strong pull-down

capability. The following formula estimates the output fall

time (90% to 10%) for a particular external load capaci-

sets the timeout period. The value of capacitor needed for

a particular timeout period is:

t

– 0.5ms

8[ms / nF]

tance (C ):

LOAD

UOTO

C

=

TMR

t

≈ 2.2 • R • C

PD LOAD

FALL

The Reset Timeout Period vs Capacitance graph found in

theTypicalPerformanceCharacteristicssectionshowsthe

desired delay time as a function of the value of the timer

capacitor that should be used. Leaving the TMR pin open

with no external capacitor generates a timeout period of

approximately 500μs. For long timeout periods, the only

limitation is the availability of a large value capacitor with

low leakage. Capacitor leakage current must not exceed

the minimum TMR charging current of 1.5μA.

where R is the on-resistance of the internal pull-down

PD

transistor estimated to be typically 40Ω at V > 1V and

DD

at room temperature (25°C), and C

is the external

LOAD

load capacitance on the pin. Assuming a 150pF load

capacitance, the fall time is about 13ns. The rise time on

the UV, OV, TO1 and TO2 pins is limited by a 400k pull-up

resistance to V . A similar formula estimates the output

DD

rise time (10% to 90%):

t

≈ 2.2 • R • C

PU LOAD

RISE

Tying the TMR pin to V will bypass the timeout period

CC

where R is the pull-up resistance.

PU

and no delay will occur.

2995f

16

LTC2995

TYPICAL APPLICATIONS

±±ꢂ0 Voltage Monitor (±.8V and ꢀ.5V) and ꢁnternal/Remote Overtemperature Monitor

2.5V

1.8V

POWER

SUPPLIES

V

CC

+

–

D

PS

0.1ꢀF

470pF

MMBT390

DS

124k

10.2k

45.3k

D

VH1

LTC2995

V

PTAT

OT T > 125°C FOR EXTERNAL SENSOR

VL1

VH2

VL2

TO2

OT T > 75°C FOR INTERNAL SENSOR

194k

TO1

OV

+10%

–10%

10.2k

UV

V

REF

VT2

VT1

GND

TMR

45.3k

5nF

20k

140k

2995 TA02

±ꢀꢂ0 Voltage Monitor (±ꢀV and 5V) and ꢂ1° to 7ꢂ1° ꢁnternal UT/OT Monitoring with °ommon

Temperature and Powergood LED

12V

5V

POWER

SUPPLIES

V

CC

+

–

2.15k

D

PS

0.1ꢀF

DS

113k

2.15k

4.12k

D

VH1

LTC2995

V

PTAT

OT T > 70°C

UT T < 0°C

+20%

VL1

VH2

VL2

TO2

442k

TO1

OV

21.5k

–20%

UV

TEMPERATURE AND

POWER GOOD LED

V

REF

VT2

VT1

GND

TMR

41.2k

2995 TA03

43k

28k

110k

2995f

17

LTC2995

TYPICAL APPLICATIONS

°elsius Thermometer and ±±ꢂ0 Voltage Monitor (±.8V and ꢀ.5V)

2.5V

1.8V

POWER

SUPPLIES

0.1ꢀF

+

–

V

D

CC

150k

1.8k

470pF

100k

MMBT3904

0.1ꢀF

PS

5V

D

DS

124k

10.2k

45.3k

1.8V

+

V

REF

VH1

10mV/°C

0V AT 0°C

LTC1150

LTC2995

1k

62k

4mV/K

V

–

PTAT

VL1

VH2

VL2

194k

143k

1ꢀF

+10%

–10%

–5V

OV

UV

10.2k

VT2

VT1

GND TMR TO2 TO1

45.3k

5nF

2995 TA04

±±ꢂ0 Voltage Monitor (±ꢀV and 5V) and –ꢀꢂ1° to 7ꢂ1° ꢁnternal UT/OT Monitor with

Manual Undervoltage Reset Button

12V

5V

POWER

SUPPLIES

V

CC

+

–

D

PS

0.1ꢀF

DS

115k

1k

D

VH1

MANUAL

RESET BUTTON

LTC2995

V

PTAT

(NORMALLY OPEN)

OT T > 70°C

UT T < –20°C

+10%

VL1

VH2

VL2

TO2

SYSTEM

4.53k

44.2k

1k

TO1

OV

–10%

RESET

UV

V

REF

VT2

VT1

GND

TMR

4.53k

2995 TA05

43k

36k

102k

2995f

18

LTC2995

PACKAGE DESCRIPTION

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

UD Package

ꢀꢂ-Lead Plastic QFN (3mm × 3mm)

(Reference LTC DWG # 05-08-1720 Rev A)

0.70 0.05

3.50 0.05

(4 SIDES)

1.65 0.05

2.10 0.05

PACKAGE

OUTLINE

0.20 0.05

0.40 BSC

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED

BOTTOM VIEW—EXPOSED PAD

PIN 1 NOTCH

R = 0.20 TYP

OR 0.25 × 45°

CHAMFER

R = 0.115

TYP

0.75 0.05

3.00 0.10

(4 SIDES)

R = 0.05

TYP

19 20

PIN 1

TOP MARK

(NOTE 6)

0.40 0.10

1

2

1.65 0.10

(4-SIDES)

(UD20) QFN 0306 REV A

0.200 REF

0.20 0.05

0.40 BSC

0.00 – 0.05

NOTE:

1. DRAWING IS NOT A JEDEC PACKAGE OUTLINE

2. DRAWING NOT TO SCALE

3. ALL DIMENSIONS ARE IN MILLIMETERS

4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE

MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE

5. EXPOSED PAD SHALL BE SOLDER PLATED

6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION

ON THE TOP AND BOTTOM OF PACKAGE

2995f

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However,noresponsibilityisassumedforitsuse.LinearTechnologyCorporationmakesnorepresenta-

t ion th a t the in ter c onne c t ion of i t s cir cui t s a s de s cr ibed her ein w ill not in fr inge on ex is t ing p a ten t r igh t s.

19

LTC2995

TYPICAL APPLICATION

Dual OV/UV ±±ꢂ0 Supply and 751°/±ꢀ51° OT/OT Remote Temperature Monitor

ASIC/

CPU/

FPGA

2.5V

1.2V

+

–

D

470pF

V

CC

D

0.1ꢀF

PS

DS

64.4k

10.2k

45.3k

VH1

LTC2995

A/D

V

PTAT

OT T > 125°C

OT T > 75°C

+10%

VL1

VH2

VL2

TO2

194k

TO1

OV

10.2k

–10%

UV

TMR

GND

5nF

VT1

VT2

V

REF

45.3k

140k

20k

2995 TA06

RELATED PARTS

PART NUMBER DES°RꢁPTꢁON

°OMMENTS

2

LTC2990

LTC2991

LTC2997

LTC2900

LTC2901

LTC2902

LTC2903

LTC2904

LTC2905

LTC2906

Remote/Internal Temperature, Voltage, Current Monitor I C Interface

2

Remote/Internal Temperature Sensor

Programmable Quad Supply Monitor

Precision Quad Supply Monitor

I C Interface, Eight Single-Ended Inputs

Analog V

Output Voltage

PTAT

Adjustable RESET, 10-Lead MSOP and 3mm × 3mm 10-Lead DFN

Adjustable RESET and Watchdog Timer, 16-Lead SSOP Package

Adjustable RESET and Tolerance, 16-Lead SSOP Package, Margining Functions

6-Lead SOT-23 Package, Ultralow Voltage Reset

3-State Programmable Precision Dual Supply Monitor Adjustable Tolerance, 8-Lead SOT-23 Package

3-State Programmable Precision Dual Supply Monitor Adjustable RESET and Tolerance, 8-Lead SOT-23 Package

Precision Dual Supply Monitor 1-Selectable and

One Adjustable

Separate V Pin, RST/RST Outputs

CC

LTC2907

LTC2908

LTC2909

Precision Dual Supply Monitor 1-Selectable and

One Adjustable

Separate V , Adjustable Reset Timer

CC

Precision Six Supply Monitor (Four Fixed and Two

Adjustable)

8-Lead SOT-23 and DDB Packages

Prevision Dual Input UV, OV and Negative Voltage

Monitor

2 ADJ Inputs, Monitors Negative Voltages

LTC2912

LTC2913

LTC2914

Single UV/OV Positive Voltage Monitor

Dual UV/OV Positive Voltage Monitor

Separate V Pin, 8-Lead TSOT and 3mm × 2mm DFN Packages

CC

Separate V Pin, 10-Lead MSOP and 3mm × 3mm DFN Packages

CC

Quad UV/OV Positive/Negative Voltage Monitor

Separate V Pin, 16-Lead SSOP and 5mm × 2mm DFN Packages

CC

2995f

LT 0412 • PRINTED IN USA

LinearTechnology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

20

●

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


型号：	LTC2995
厂家：	Linear Systems
描述：	Temperature Sensor and Dual Voltage Monitor with Alert Outputs 温度传感器和双通道电压监视器与警报输出传感器温度传感器监视器
文件：	总20页 (文件大小：221K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LTC2995 [Linear Systems]

相关型号：

SI9130DB

SI9135LG-T1

SI9135LG-T1-E3

SI9135_11

SI9136_11

SI9130CG-T1-E3

SI9130LG-T1-E3

SI9130_11

SI9137

SI9137DB

SI9137LG

SI9122E