LTC2914IGN-2#PBF_技术文档

LTC2914

Quad UV/OV

Positive/Negative

Voltage Monitor

FeaTures

DescripTion

TheLTC^®2914isaquadinputvoltagemonitorintendedfor

monitoring multiple voltages in a variety of applications.

Dual inputs for each monitored voltage allow monitor-

ing four separate undervoltage (UV) conditions and four

separate overvoltage (OV) conditions. All monitors share

a common undervoltage output and a common overvolt-

age output. The LTC2914-1 has latching capability for the

overvoltage output. The LTC2914-2 has functionality to

disable both the overvoltage and undervoltage outputs.

n

Monitors Four Voltages Simultaneously

n

Adjustable UV and OV Trip Values

n

Guaranteed Threshold Accuracy: ±±1.5 oꢀ

Monitored Voltage over Temperature

n

Input Glitch Rejection

n

Monitors up to Two Negative Voltages

n

Buffered 1V Reference Output

n

Adjustable Reset Timeout with Timeout Disable

n

62µA Quiescent Current

n

Open-Drain OV and UV Outputs

Polarity selection and a buffered reference allow monitor-

ing up to two separate negative voltages. A three-state

input pin allows setting the polarity of two inputs without

requiringanyexternalcomponents.Glitchfilteringensures

reliable reset operation without false or noisy triggering.

n

Guaranteed OV and UV for V ≥ 1V

CC

n

Available in 16-Lead SSOP and 16-Lead

(5mm × 3mm) DFN Packages

applicaTions

The LTC2914 provides a precise, versatile, space-con-

scious, micropower solution for voltage 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

Desktop and Notebook Computers

n

Network Servers

n

Core, I/O Voltage Monitors

Typical applicaTion

Quad UV/OV Supply Monitor,±05 Tolerance, .V, 313V, 21.V, ±18V

5V

3.3V

2.5V

1.8V

P0WER

SUPPLIES

Input Threshold Voltage

0.1μF

vs Temperature

0.505

0.504

0.503

0.502

44.2k

V

CC

VH1

SEL

1k

27.4k

VL1

VH2

OV

SYSTEM

0.501

0.500

0.499

0.498

0.497

0.496

0.495

LTC2914-1

4.53k 1k

4.53k 19.6k

UV

VL2

REF

VH3

LATCH

1k

12.4k

VL3

VH4

–50

–25

25

50

75

100

0

4.53k 1k

TEMPERATURE (°C)

VL4

2914 TA01b

GND TMR

4.53k

2914 TA01a

C

TMR

22nF

TIMEOUT = 200ms

2914fc

1

For more information www.linear.com/LTC2914

LTC2914

absoluTe MaxiMuM raTings _{(Notes ±, 2)}

Terminal Voltages

Operating Temperature Range

V

(Note 3)............................................. –0.3V to 6V

LTC2914C ................................................ 0°C to 70°C

LTC2914I .............................................–40°C to 85°C

LTC2914H.......................................... –40°C to 125°C

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

Lead Temperature (Soldering, 10 sec)

CC

OV, UV ................................................... –0.3V to 16V

TMR..........................................–0.3V to (V + 0.3V)

CC

VLn, VHn, LATCH, DIS, SEL ...................–0.3V to 7.5V

Terminal Currents

I

....................................................................10mA

SSOP ................................................................300°C

VCC

Reference Load Current (I ) ........................... 1mA

REF

I , I ...............................................................10mA

UV OV

pin conFiguraTion

TOP VIEW

VH1

VL1

VH2

VL2

VH3

VL3

VH4

VL4

1

2

3

4

5

6

7

8

16

15

14

13

12

11

10

9

V

CC

VH1

VL1

VH2

VL2

VH3

VL3

VH4

VL4

1

2

3

4

5

6

7

8

16 V

CC

TMR

SEL

15 TMR

14 SEL

LATCH/DIS

UV

13 LATCH/DIS

12 UV

17

OV

11 OV

REF

10 REF

GND

9

GND

GN PACKAGE

16-LEAD PLASTIC SSOP

= 150°C, θ = 110°C/W

DHC PACKAGE

16-LEAD (5mm × 3mm) PLASTIC DFN

T

JMAX

JA

T

= 150°C, θ = 43.5°C/W

JA

JMAX

EXPOSED PAD (PIN 17)

PCB GND CONNECTION OPTIONAL

orDer inForMaTion

LEAD FREE FINISH

TAPE AND REEL

PART MARKING*

29141

PACKAGE DESCRIPTION

TEMPERATURE RANGE

0°C to 70°C

LTC2914CDHC-1#PBF

LTC2914IDHC-1#PBF

LTC2914HDHC-1#PBF

LTC2914CDHC-2#PBF

LTC2914IDHC-2#PBF

LTC2914HDHC-2#PBF

LTC2914CGN-1#PBF

LTC2914IGN-1#PBF

LTC2914HGN-1#PBF

LTC2914CDHC-1#TRPBF

LTC2914IDHC-1#TRPBF

LTC2914HDHC-1#TRPBF

LTC2914CDHC-2#TRPBF

LTC2914IDHC-2#TRPBF

LTC2914HDHC-2#TRPBF

LTC2914CGN-1#TRPBF

LTC2914IGN-1#TRPBF

LTC2914HGN-1#TRPBF

16-Lead Plastic (5mm × 3mm) DFN

16-Lead Plastic SSOP

29141

–40°C to 85°C

–40°C to 125°C

0°C to 70°C

29141

29142

–40°C to 85°C

–40°C to 125°C

0°C to 70°C

29142

29141

2914I1

2914H1

16-Lead Plastic SSOP

–40°C to 85°C

–40°C to 125°C

16-Lead Plastic SSOP

2914fc

2

For more information www.linear.com/LTC2914

LTC2914

orDer inForMaTion

LEAD FREE FINISH

LTC2914CGN-2#PBF

LTC2914IGN-2#PBF

LTC2914HGN-2#PBF

TAPE AND REEL

PART MARKING*

29142

PACKAGE DESCRIPTION

16-Lead Plastic SSOP

TEMPERATURE RANGE

0°C to 70°C

LTC2914CGN-2#TRPBF

LTC2914IGN-2#TRPBF

LTC2914HGN-2#TRPBF

2914I2

–40°C to 85°C

2914H2

–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

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/

The l denotes the speciꢀications which apply over the ꢀull operating

elecTrical characTerisTics

DIS = Open unless otherwise noted1 (Note 2)

temperature range, otherwise speciꢀications are at T_A= 2.°C1 V_CC= 313V, VLn = 014.V, VHn = 01..V, LATCH = V_CC, SEL = V_CC

,

SYMBOL

PARAMETER

CONDITIONS

I = 5mA

CC

MIN

6.2

TYP

6.6

MAX

6.9

UNITS

V

l

V

Shunt Regulator Voltage

SHUNT

CC

–40ºC < T < 125ºC

6.2

6.6

7.0

V

A

V

Shunt Regulator Load Regulation

I

CC

= 2mA to 10mA

200

300

mV

V

ΔV

SHUNT

V

Supply Voltage (Note 3)

2.3

V

SHUNT

CC

Minimum V Output Valid

DIS = 0V

Rising, DIS = 0V

1

V

CCR(MIN)

CC(UVLO)

CC

Supply Undervoltage Lockout

Supply Undervoltage Lockout Hysteresis

Supply Current

V

CC

1.9

5

2

25

62

1

2.1

50

V

DIS = 0V

mV

µA

V

ΔV

CC(UVHYST)

I

CC

V

CC

= 2.3V to 6V

100

V

REF

Reference Output Voltage

I

= 1mA

0.985

492

1.015

1.020

508

VREF

–40ºC < T < 125ºC

1

V

A

V

Undervoltage/Overvoltage Voltage Threshold

500

125

mV

µs

UOT

UOD

t

I

Undervoltage/Overvoltage Voltage Threshold VHn = V

to Output Delay

– 5mV or VLn = V

+ 5mV

50

500

UOT

l

VHn, VLn Input Current

15

30

nA

ms

V

VHL

–40ºC < T < 125ºC

A

t

UV/OV Time-Out Period

C

TMR

= 1nF

6

8.5

12.5

14

UOTO

–40ºC < T < 125ºC

A

V

OV Latch Clear Input High

OV Latch Clear Threshold Input Low

LATCH Input Current

DIS Input High

1.2

LATCH(IH)

LATCH(IL)

LATCH

0.8

1

V

I

V

LATCH

> 0.5V

µA

V

1.2

DIS(IH)

DIS(IL)

DIS

DIS Input Low

0.8

3

V

I

DIS Input Current

V

> 0.5V

1

2

µA

DIS

TMR Pull-Up Current

= 0V

–1.3

–1.2

1.3

–2.1

2.1

–2.8

2.8

TMR(UP)

TMR

–40ºC < T < 125ºC

A

I

TMR Pull-Down Current

V

TMR

= 1.6V

TMR(DOWN)

–40ºC < T < 125ºC

1.2

2.1

A

2914fc

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For more information www.linear.com/LTC2914

LTC2914

The l denotes the speciꢀications which apply over the ꢀull operating

elecTrical characTerisTics

DIS = Open unless otherwise noted1 (Note 2)

temperature range, otherwise speciꢀications are at T_A= 2.°C1 V_CC= 313V, VLn = 014.V, VHn = 01..V, LATCH = V_CC, SEL = V_CC

,

SYMBOL

PARAMETER

CONDITIONS

MIN

–180

1

TYP

MAX

UNITS

mV

l

V

Timer Disable Voltage

Output Voltage High UV/OV

Output Voltage Low UV/OV

Referenced to V

–270

TMR(DIS)

OH

CC

UV/OV

V

= 2.3V, I

= –1µA

V

CC

l

V

CC

V

CC

= 2.3V, I

= 2.5mA

0.1

0.01

0.3

0.15

V

OL

= 1V, I = 100µA

UV

Three-State Input SEL

l

V

Low Level Input Voltage

0.4

V

IL

IH

Z

High Level Input Voltage

1.4

0.7

0.6

Pin Voltage when Left in Hi-Z State

I

= 10µA

0.9

1.1

1.2

25

V

SEL

–40ºC < T < 125ºC

V

A

I

t

SEL High, Low Input Current

Maximum SEL Input Current

Latch Clear Pulse Width

µA

µs

SEL

SEL Tied to Either V or GND

30

SEL(MAX)

PW

CC

(Note 4)

2

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: V maximum pin voltage is limited by input current. Since the

CC

V

pin has an internal 6.5V shunt regulator, a low impedance supply that

CC

exceeds 6V may exceed the rated terminal current. Operation from higher

voltage supplies requires a series dropping resistor. See Applications

Information.

Note 2: All currents into pins are positive; all voltages are referenced to

GND unless otherwise noted.

Note 4: Guaranteed by design, not subject to test.

2914fc

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LTC2914

TiMing DiagraMs

VHn Monitor Timing

VLn Monitor Timing

V

UOT

VHn

VLn

UOT

t

UOTO

UOD

UOTO

UOD

UV

1V

OV

1V

2914 TD01

2914 TD02

VHn Monitor Timing (TMR Pin Strapped to V_CC

)

VLn Monitor Timing (TMR Pin Strapped to V_CC

)

V

UOT

VHn

VLn

UOT

t

UOD

UV

1V

OV

1V

2914 TD03

2914 TD04

NOTE: WHEN AN INPUT IS CONFIGURED AS A NEGATIVE SUPPLY MONITOR, VHn WILL TRIGGER AN OV CONDITION AND VLn WILL TRIGGER A UV CONDITION

Typical perForMance characTerisTics

Speciꢀications are at T_A= 2.°C, V_CC= 313V unless otherwise noted1

Input Threshold Voltage

vs Temperature

V_CCShunt Voltage

vs Temperature

Supply Current vs Temperature

75

70

65

60

55

50

45

40

6.8

6.7

6.6

6.5

6.4

6.3

6.2

0.505

0.504

0.503

0.502

0.501

0.500

0.499

0.498

0.497

0.496

0.495

V

= 5V

CC

10mA

5mA

V

= 3.3V

2mA

1mA

V

= 2.3V

CC

200μA

–50

–25

25

50

75

100

–50

0

25

50

75

100

0

–50

–25

0

25

50

75

100

–25

TEMPERATURE (°C)

2914 G01

2914 G03

2914 G02

2914fc

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LTC2914

Typical perForMance characTerisTics

Speciꢀications are at T_A= 2.°C, V_CC= 313V unless otherwise noted1

Buꢀꢀered Reꢀerence Voltage

vs Temperature

Transient Duration

vs Comparator Overdrive

V_CCShunt Voltage vs I_CC

6.75

6.65

6.55

6.45

6.35

6.25

1.005

1.004

1.003

1.002

1.001

1.000

0.999

0.998

0.997

0.996

0.995

700

600

500

400

300

200

100

0

RESET OCCURS

ABOVE CURVE

25°C

–40°C

85°C

V

= 6V

CC

V

= 2.3V

CC

–50

–25

25

50

75

100

–2

0

2

4

6

8

10

12

0

0.1

1

10

100

TEMPERATURE (°C)

I

(mA)

COMPARATOR OVERDRIVE PAST THRESHOLD (%)

CC

2914 G06

2914 G05

2914 G04

Reset Timeout Period

vs Temperature

UV Output Voltage vs V_CC

12

11

10

9

0.8

0.6

0.4

0.2

0

5

C

= 1nF

VHn = 0.55V

SEL = V

TMR

CC

V

CC

4

3

2

1

0

UV WITH

10k PULL-UP

8

UV WITHOUT

10k PULL-UP

7

6

–50

0

25

50

75

100

–25

0

0.2

0.4

0.6

0.8

1.0

0

1

2

3

4

5

TEMPERATURE (°C)

SUPPLY VOLTAGE, V (V)

CC

2914 G07

2914 G08

2914 G09

UV/OV Voltage Output Low

Reset Timeout Period

vs Capacitance

UV, I_SINKvs V_CC

vs Output Sink Current

1.0

0.8

0.6

0.4

10000

1000

100

5

4

3

2

1

0

VHn = 0.45V

SEL = V

CC

85°C

25°C

UV AT 150mV

–40°C

UV AT 50mV

10

1

0.2

0

10

15

(mA)

20

25

30

5

0.1

1

10

100

(nF)

1000

0

1

2

3

4

5

I

TMR PIN CAPACITANCE, C

SUPPLY VOLTAGE, V (V)

TMR

UV/OV

CC

2914 G12

2914 G11

2914 G10

2914fc

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LTC2914

pin FuncTions

UV(Pin±2):UndervoltageLogicOutput.Assertslowwhen

any positive polarity input voltage is below threshold or

any negative polarity input voltage is above threshold.

Held low for an adjustable delay time after all voltage

DIS (Pin ±3, LTC29±4-2): Output Disable Input. Disables

the OV and UV output pins. When DIS is pulled high, the

OV and UV pins are not asserted except during a UVLO

condition.Pinhasaweak(2µA)internalpull-downtoGND.

Leave pin open if unused.

inputs are valid. Pin has a weak pull-up to V and may

CC

be pulled above V using an external pull-up. Leave pin

CC

Exposed Pad (Pin ±7, DFN Package): Exposed Pad may

be left open or connected to device ground.

open if unused.

V

CC

(Pin ±6): Supply Voltage. Bypass this pin to GND with

GND (Pin 9): Device Ground

a 0.1µF (or greater) capacitor. Operates as a direct supply

input for voltages up to 6V. Operates as a shunt regula-

tor for supply voltages greater than 6V and must have a

resistance between the pin and the supply to limit input

current to no greater than 10mA. When used without a

current-limitingresistance,pinvoltagemustnotexceed6V.

LATCH(Pin±3,LTC29±4-±):OVLatchClear/BypassInput.

When pulled low, OV is latched when asserted. When

pulled high, OV latch is cleared. While held high, OV has

the same delay and output characteristics as UV.

OV (Pin ±±): Overvoltage Logic Output. Asserts low when

any positive polarity input voltage is above threshold or

any negative polarity input voltage is below threshold.

Latched low (LTC2914-1). Held low for an adjustable

delay time after all inputs are valid (LTC2914-2). Pin has

VH±/VH2(Pin±/Pin3):VoltageHighInputs1and2.When

the voltage on this pin is below 0.5V, an undervoltage

condition is triggered. Tie pin to V if unused.

CC

VH3/VH4 (Pin ./Pin 7): Voltage High Inputs 3 and 4. The

polarity of the input is selected by the state of the SEL pin

(refer to Table 1). When the monitored input is configured

as a positive voltage, an undervoltage condition is trig-

gered when the pin is below 0.5V. When the monitored

input is configured as a negative voltage, an overvoltage

condition is triggered when the pin is below 0.5V. Tie pin

a weak pull-up to V and may be pulled above V using

CC

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

REF (Pin ±0): Buffered Reference Output. 1V reference

used for the offset of negative-monitoring applications.

The buffered reference sources and sinks up to 1mA. The

referencedrivescapacitiveloadsup to 1nF. Largercapaci-

tive loads may cause instability. Leave pin open if unused.

to V if unused.

CC

SEL (Pin ±4): Input Polarity Select Three-State Input.

VL±/VL2 (Pin 2/Pin 4): Voltage Low Inputs 1 and 2. When

thevoltageonthispinisabove0.5V,anovervoltagecondi-

tion is triggered. Tie pin to GND if unused.

Connect to V , GND or leave unconnected in open state

CC

to select one of three possible input polarity combinations

(refer to Table 1).

VL3/VL4 (Pin 6/Pin 8): Voltage Low Inputs 3 and 4. The

polarity of the input is selected by the state of the SEL pin

(refer to Table 1). When the monitored input is configured

as a positive voltage, anovervoltage condition is triggered

when the pin is above 0.5V. When the monitored input is

configured as a negative voltage, an undervoltage condi-

tion is triggered when the pin is above 0.5V. Tie pin to

GND if unused.

T

MR (Pin ±.): Reset Delay Timer. Attach an external

capacitor (C

) of at least 10pF to GND to set a reset

TMR

delay time of 9ms/nF. A 1nF capacitor will generate an

8.5ms reset delay time. Tie pin to V to bypass timer.

CC

2914fc

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LTC2914

block DiagraM

16

15

TMR

V

CC

V

CC

VH1

–

+

400k

OSCILLATOR

1

UV

12

–

+

UV PULSE

GENERATOR

VL1

VH2

2

3

–

+

V

UVLO

CC

+

–

2V

V

400k

–

+

CC

OV PULSE

VL2

VH3

UVLO

GENERATOR

OV

4

5

11

DISABLE

–

+

OV LATCH

CLEAR/BYPASS

LATCH

–

+

–

13

VL3

VH4

1V

6

7

LTC2914-1

LTC2914-2

–

+

DIS

+

–

2μA

–

+

VL4

8

GND

9

0.5V

REF

THREE-STATE

POLARITY

DECODER

10

1V

SEL

14

BUFFER

2914 -1 BD

2914fc

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LTC2914

applicaTions inForMaTion

Voltage Monitoring

The three-state input pin SEL is connected to GND, V or

CC

left unconnected during normal operation. When the pin

is left unconnected, the maximum leakage allowed from

the pin is 10µA to ensure it remains in the open state.

Table 1 shows the three possible selections of polarity

based on the SEL pin connection.

The LTC2914 is a low power quad voltage monitoring cir-

cuit with four undervoltage and four overvoltage inputs. A

timeout period that holds OV or UV asserted after all faults

have cleared is adjustable using an external capacitor and

is externally disabled.

Table ±1 Voltage Polarity Programming (V_UOT= 01.V Typical)

Each voltage monitor has two inputs (VHn and VLn) for

detectingundervoltageandovervoltageconditions.When

SEL

V3 INPUT

V4 INPUT

V

Positive

CC

configured to monitor a positive voltage V using the

n

VH3 < V

→ UV

→ OV

VH4 < V

→ UV

→ OV

UOT

3-resistor circuit configuration shown in Figure 1, VHn is

connected to the high-side tap of the resistive divider and

VLnisconnectedtothelow-sidetapoftheresistivedivider.

If an input is configured as a negative voltage monitor, the

VL3 > V

VL4 > V

Open

GND

Positive

Negative

VH3 < V

→ UV

→ OV

VH4 < V

→ OV

→ UV

UOT

VL3 > V

VL4 > V

outputsUV andOV inFigure1areswappedinternally.V

n

Negative

is then connected as shown in Figure 2. Note, VHn is still

connected to the high-side tap and VLn is still connected

to the low-side tap.

VH3 < V

→ OV

VH4 < V

→ OV

→ UV

UOT

VL3 > V

→ UV

VL4 > V

3-Step Design Procedure

Polarity Selection

The following 3-step design procedure allows selecting

appropriateresistancestoobtainthedesiredUVandOVtrip

points for the positive voltage monitor circuit in Figure 1

and the negative voltage monitor circuit in Figure 2. 1%

resistor tolerances are suggested to maintain the 1.5%

threshold accuracy.

Thethree-statepolarity-selectpin(SEL)selectsoneofthree

possible polarity combinations for the input thresholds,

as described in Table 1. When an input is configured for

negativesupplymonitoring,VHnisconfiguredtotriggeran

overvoltage condition and VLn is configured to trigger an

undervoltagecondition.Withthisconfiguration,anOVcon-

ditionoccurswhenthesupplyvoltageismorenegativethan

the configured threshold and a UV condition occurs when

thevoltageislessnegativethantheconfiguredthreshold.

LTC2914

+

REF

+

1V

–

V

n

LTC2914

VHn

R

C

–

+

R

A

VHn

–

+

UV

OV

n

OV

UV

n

+

–

R

0.5V

B

+

0.5V

B

–

+

–

+

n

VLn

n

VLn

R

A

R

C

2914 F01

2914 F02

V

n

Figure ±1 3-Resistor Positive UV/OV Monitoring Conꢀiguration

Figure 21 3-Resistor Negative UV/OV Monitoring Conꢀiguration

2914fc

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LTC2914

applicaTions inForMaTion

V1

V

CC

5V

For positive supply monitoring, V is the desired nomi-

n

5V ±10%

nal operating voltage, I is the desired nominal current

nd

R

C

through the resistive divider, I is the resistive divider

V

CC

na

442k

VH1

OV

current calculated using the 1% resistor R . V is the

A

OV

R

B

LTC2914

10k

desired overvoltage trip point and V is the desired

UV

VL1

UV

undervoltage trip point.

R

A

45.3k

SEL

GND

For negative supply monitoring, to compensate for the 1V

2914 F03

reference, 1V must be subtracted from V , V and V

n

OV

UV

before using each in the following equations.

Figure 31 Positive Supply Monitor

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

±A1Choose R to obtain the desired OV trip point

A

R is chosen to set the desired trip point for the over-

0.5V 5V

10µA 5.5V

A

R_A=

•

≈ 45.3k

voltage monitor.

0.5V V_n

1B.Calculate I

na

R_A=

•

(1)

I_nV_OV

±B1Calculate I

0.5V 5V

•

I_na=

=10.034µA

na

45.3k 5.5V

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

0.5V V_n

•

B

I_na=

R_AV_OV

0.5V

5V

R_B=

•

–45.3k ≅10k

10.034µA 4.5V

21 Choose R to obtain the desired UV trip point

B

3. Determine R to complete the design.

Once R is known, R is chosen to set the desired trip

C

A

B

point for the undervoltage monitor.

5V

10.034µA

R_C=

–45.3k−10k ≈ 442k

0.5V V_n

R_B=

•

–R_A

(2)

I_naV_UV

31 Choose R to Complete the Design

Negative Voltage Monitor Example ±

C

AnegativevoltagemonitorapplicationisshowninFigure 4.

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

current in the resistive divider is 10µA. For the negative

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

A

B

C

V_n

I_na

R_C=

–R_A–R_B

(3)

case, 1V is subtracted from V , V and V .

n

OV

UV

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

A

If any of the variables V , I , I , V or V change, then

n

na nd UV

OV

each step must be recalculated.

0.5V –5V –1V

R_A=

•

≈ 46.4k

10µA –5.5V –1V

1B. Calculate I

Positive Voltage Monitor Example

na

ApositivevoltagemonitorapplicationisshowninFigure 3.

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

current in the resistive divider is 10µA.

0.5V –5V –1V

46.4k –5.5V –1V

I_no

•

= 9.947µA

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

B

0.5V

–5V –1V

R_B=

•

−46.4k ≅ 8.45k

9.947µA –4.5V –1V

2914fc

10

For more information www.linear.com/LTC2914

LTC2914

applicaTions inForMaTion

3. Determine R to complete the design.

2. Calculate R

based on the desired undervoltage trip

V_UV

C

CUV

point of –6V.

–5V –1V

9.947µA

R_C=

−46.4k−8.45k ≈549k

R_CUV=(R_AUV+R_BUV)•

=

V

V_REF

CC

5V

–6V –1V

(49.9k+49.9k)•

3. Calculate R and I

≈698k

V

CC

1V

REF

OV

UV

R

A

LTC2914

46.4k

AOV

na

VH3

VL3

R

B

8.45k

V

_REF–0.5V 1V –0.5V

SEL

R_AOV

=

≈ 49.9k

R

C

I_nd

10µA

GND

549k

2914 F04

V3

–5V ±10%

I_na≈10.020µA

4. Calculate R

for a desired overvoltage trip point of

Figure 41 Negative Supply Monitor

BOV

–30V.

Negative Voltage Monitoring Example 2

0.5V – V_OV0.5V –30–1

R_BOV

=

≈3.01M

I_na

10.020µA

Negativevoltagemonitoringapplicationswithwideoperat-

ing voltage ranges such that:

V

CC

5V

2•V_UV< V_OV

V

CC

create situations where the VH or VL pins exceeds the

–0.3V absolute maximum voltage ratings. To ensure that

the LTC2914 operates within its design specifications,

utilize the equations shown below to determine proper

resistor sizing for the circuit in Figure 5. In the following

example, the undervoltage trip point is –6V. The overvolt-

age trip point is –30V.

REF

VH3

VL3

OV

UV

R

AOV

LTC2914

49.9k

R

AUV

49.9k

R

BOV

3.01M

SEL

R

BUV

GND

D1

49.9k

A

2914 F05

R

CUV

698k

1A. Find R

and R

and let node A be a virtual ground,

AUV

BUV

V3

which ensures that the diode current will not affect the

voltage monitor threshold accuracy. Let the resistive

Figure .1 Negative Supply Monitor ꢀor Wide Operating Range

divider current I = 10µA.

nd

Power-Up/Power-Down

V

_REF–0.5V 1V –0.5V

R_AUV

=

≈ 49.9k

AssoonasV reaches1Vduringpower-up,theUVoutput

I_nd

R_AUV=R_BUV

1B. Calculate I using the resistor values chosen above.

10µA

CC

asserts low and the OV output weakly pulls to V .

CC

The LTC2914 is guaranteed to assert UV low and OV high

under conditions of low V , down to V = 1V. Above V

na

CC

= 2V (2.1V maximum) the VH and VL inputs take control.

V

_REF–0.5V 1V –0.5V

R_AUV

I_na=

=

≈10.020µA

Once all VH inputs and V become valid an internal timer

CC

R_AUV

is started. After an adjustable delay time, UV weakly pulls

high.

2914fc

11

For more information www.linear.com/LTC2914

LTC2914

applicaTions inForMaTion

Threshold Accuracy

Glitch Immunity

Resetthresholdaccuracyisimportantinasupply-sensitive

system.Ideally,suchasystemresetsonlyifsupplyvoltages

fall outside the exact thresholds for a specified margin.

All LTC2914 inputs have a relative threshold accuracy of

1.5% over the full operating temperature range.

In any supervisory application, noise riding on the moni-

tored DC voltage causes spurious resets. To solve this

problem without adding hysteresis, which causes a new

error term in the trip voltage, the LTC2914 lowpass filters

the output of the first stage comparator at each input. This

filter integrates the output of the comparator before as-

serting the UV or OV logic. A transient at the input of the

comparator of sufficient magnitude and duration triggers

the output logic. The Typical Performance Characteristics

section shows a graph of the Transient Duration vs Com-

parator Overdrive.

For example, when the LTC2914 is programmed to moni-

tor a 5V input with a 10% tolerance, the desired UV trip

point is 4.5V. Because of the 1.5% relative accuracy of

the LTC2914, the UV trip point is between 4.433V and

4.567V which is 4.5V 1.5%.

Likewise, the accuracy of the resistances chosen for R ,

A

R and R affect the UV and OV trip points as well. Us-

UV/OV Timing

B

C

ing the example just given, if the resistances used to set

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

is between 4.354V and 4.650V. This is illustrated in the

following calculations.

TheLTC2914hasanadjustabletimeoutperiod(t

)that

UOTO

holds OV or UV asserted after all faults have cleared. This

assures a minimum reset pulse width allowing a settling

time delay for the monitored voltage after it has entered

the valid region of operation.

The UV trip point is given as:

When any VH input drops below its designed threshold,

the UV pin asserts low. When all inputs recover above

their designed thresholds, the UV output timer starts. If

all inputs remain above their designed thresholds when

the timer finishes, the UV pin weakly pulls high. However,

if any input falls below its designed threshold during this

time-out period, the timer resets and restarts when all

inputs are above the designed thresholds. The OV output

behavesastheUVoutputwhenLATCHishigh(LTC2914-1).





_B

R_C

R_A+R

V_UV= 0.5V 1+







The two extreme conditions, with a relative accuracy of

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







R_C•0.99

V_UV(MIN)= 0.5V •0.985• 1+



R +R •1.01

(

)





A

B

and

Selecting the UV/OV Timing Capacitor





R_C•1.01

V_UV(MAX)= 0.5V •1.015• 1+





The UV and OV timeout period (t ) for the LTC2914

UOTO

R +R •0.99

(

)





A

B

is adjustable to accommodate a variety of applications.

Connecting a capacitor, C , between the TMR pin and

R_C

R_A+R_B

For a desired trip point of 4.5V,

= 8

TMR

ground sets the timeout period. The value of capacitor

needed for a particular timeout period is:

Therefore,

–9

C

TMR

= t

• 115 • 10 (F/s)

UOTO

0.99

1.01





V_UV(MIN)= 0.5V •0.985• 1+8•

= 4.354V

= 4.650V







The Reset Timeout Period vs Capacitance graph found in

theTypicalPerformanceCharacteristicsshowsthedesired

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

that must be used. The TMR pin must have a minimum of



and

V_UV(MAX)= 0.5V •1.015• 1+8•

1.01

0.99











10pF or be tied to V . For long timeout periods, the only



CC

limitation is the availability of a large value capacitor with

2914fc

12

For more information www.linear.com/LTC2914

LTC2914

applicaTions inForMaTion

low leakage. Capacitor leakage current must not exceed

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

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

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

strength of any single device must accommodate this

additional pull-up strength.

the minimum TMR charging current of 1.3µA. Tying the

TMR pin to V bypasses the timeout period.

CC

Undervoltage Lockout

When V falls below 2V, the LTC2914 asserts an under-

CC

Output Rise and Fall Time Estimation

voltage lockout (UVLO) condition. During UVLO, UV is

asserted and pulled low while OV is cleared and blocked

The UV and OV outputs have strong pull-down capability.

from asserting. When V rises above 2V, UV follows the

The following formula estimates the output fall time (90%

CC

same timing procedure as an undervoltage condition on

to 10%) for a particular external load capacitance (C

):

LOAD

any input.

t

≈ 2.2 • R • C

PD LOAD

FALL

Shunt Regulator

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

PD

transistor, typically 50Ω at V > 1V and at room tem-

CC

The LTC2914 has an internal shunt regulator. The V pin

CC

perature (25°C). C

is the external load capacitance

on the pin. Assuming a 150pF load capacitance, the fall

LOAD

operates as a direct supply input for voltages up to 6V.

Under this condition, the quiescent current of the device

time is 16.5ns.

remains below a maximum of 100µA. For V voltages

CC

higher than 6V, the device operates as a shunt regulator

The rise time on the UV and OV pins is limited by a 400k

and must have a resistance R between the supply and

pull-up resistance to V . A similar formula estimates the

Z

CC

the V pin to limit the current to no greater than 10mA.

output rise time (10% to 90%) at the UV and OV pins:

CC

Whenchoosingthisresistancevalue,chooseanappropriate

locationontheI-VcurveshownintheTypicalPerformance

t

≈ 2.2 • R • C

RISE PU LOAD

where R is the pull-up resistance.

PU

Characteristics section to accommodate variations in V

CC

OV Latch (LTC29±4-±)

due to changes in current through R .

Z

With the LATCH pin held low, the OV pin latches low

when an OV condition is detected. The latch is cleared by

raising the LATCH pin high. If an OV condition changes

while LATCH is held high, the latch is bypassed and the

OV pin behaves the same as the UV pin with a similar

timeout period at the output. If LATCH is pulled low while

the timeout period is active, the OV pin latches as before.

UV and OV Output Characteristics

The DC characteristics of the UV and OV pull-up and

pull-down strength are shown in the Typical Performance

Characteristics section. Each pin has a weak internal

pull-up to V and a strong pull-down to ground. This ar-

CC

rangement allows these pins to have open-drain behavior

while possessing several other beneficial characteristics.

The weak pull-up eliminates the need for an external pull-

up resistor when the rise time on the pin is not critical.

On the other hand, the open-drain configuration allows

for wired-OR connections and is useful when more than

Disable (LTC29±4-2)

TheLTC2914-2allowsdisablingtheUVandOVoutputsvia

theDISpin. PullingDIShighforcesbothoutputstoremain

weakly pulled high, regardless of any faults that occur on

the inputs. However, if a UVLO condition occurs, UV as-

serts and pulls low, but the timeout function is bypassed.

UV pulls high as soon as the UVLO condition is cleared.

one signal needs to pull down on the output. V of 1V

CC

guarantees a maximum V = 0.15V at UV.

OL

AtV =1V,theweakpull-upcurrentonOVisbarelyturned

CC

on. Therefore, an external pull-up resistor of no more

DIS has a weak 2µA (typical) internal pull-down current

guaranteeing normal operation with the pin left open.

than 100k is recommended on the OV pin if the state and

pull-up strength of the OV pin is crucial at very low V .

CC

2914fc

13

For more information www.linear.com/LTC2914

LTC2914

Typical applicaTions

Quad UV/OV Supply Monitor, ±05 Tolerance, .V, 313V, 21.V, ±18V

5V

3.3V

2.5V

1.8V

P0WER

SUPPLIES

C

0.1μF

BYP

1

16

R

C1

V

CC

44.2k

14

11

12

VH1

SEL

R

C2

B1

LTC2914-1

27.4k

1k

2

3

VL1

OV

SYSTEM

VH2

R

A1

R

B2

UV

4.53k

1k

4

VL2

REF

VH3

10

5

R

C3

A2

19.6k

4.53k

13

LATCH

R

C4

12.4k

B3

1k

6

7

VL3

VH4

R

B4

1k

A3

4.53k

8

VL4

GND TMR

R

A4

4.53k

2914 TA02

9

15

C

TMR

TIMEOUT = 200ms

22nF

Dual Positive and Dual Negative UV/OV Supply Monitor,

±05 Tolerance, .V, 313V, –.V, –313V

5V

P0WER

SUPPLIES

3.3V

C

BYP

0.1μF

16

R

C1

V

CC

44.2k

1

VH1

R

B1

C2

1k

27.4k

2

3

VL1

VH2

11

12

OV

R

B2

A1

LTC2914-1

1k

4.53k

4

VL2

UV

LATCH

SEL

10

REF

VH3

SYSTEM

R

4.53k

R

A2

A3

4.64k

13

14

5

R

A4

B3

845Ω 4.64k

6

7

VL3

VH4

R

C3

54.9k

R

B4

768Ω

8

VL4

GND TMR

R

C4

37.4k

9

15

C

TMR

2.2nF

TIMEOUT = 20ms

–3.3V

–5V

2914 TA03

2914fc

14

For more information www.linear.com/LTC2914

LTC2914

Typical applicaTions

Triple UV/OV Supply Monitor Powered ꢀrom 48V, ±05 Tolerance, 48V, .V, 21.V

48V

R

Z

P0WER

SUPPLIES

8.25k

5V

2.5V

C

0.1μF

BYP

16

R

C1

V

475k

CC

1

14

VH1

SEL

R

C2

B1

1k

44.2k

2

3

15

11

VL1

VH2

TMR

SYSTEM

OV

R

A1

R

B2

LTC2914-1

4.53k 1k

12

13

4

10

5

VL2

REF

VH3

UV

R

A2

C3

4.53k

19.6k

LATCH

R

B3

1k

6

7

VL3

VH4

R

4.53k

A3

8

VL4

GND

2914 TA04

9

2914fc

15

For more information www.linear.com/LTC2914

LTC2914

package DescripTion

Please reꢀer to http://www1linear1com/designtools/packaging/ ꢀor the most recent package drawings1

DHC Package

16-Lead Plastic DFN (5mm × 3mm)

(Reference LTC DWG # 05-08-1706 Rev Ø)

R = 0.115

TYP

0.40 0.10

5.00 0.10

(2 SIDES)

9

16

R = 0.20

TYP

0.65 0.05

3.50 0.05

PIN 1

TOP MARK

(SEE NOTE 6)

1.65 0.05

3.00 0.10 1.65 0.10

2.20 0.05 (2 SIDES)

(2 SIDES)

PIN 1

NOTCH

PACKAGE

OUTLINE

(DHC16) DFN 1103

8

1

0.25 0.05

0.50 BSC

0.75 0.05

0.200 REF

0.25 0.05

0.50 BSC

4.40 0.10

(2 SIDES)

4.40 0.05

(2 SIDES)

0.00 – 0.05

BOTTOM VIEW—EXPOSED PAD

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

NOTE:

1. DRAWING PROPOSED TO BE MADE VARIATION OF VERSION (WJED-1) IN JEDEC

PACKAGE OUTLINE MO-229

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

2. DRAWING NOT TO SCALE

3. ALL DIMENSIONS ARE IN MILLIMETERS

GN Package

16-Lead Plastic SSOP (Narrow .150 Inch)

(Reference LTC DWG # 05-08-1641 Rev B)

.189 – .196*

(4.801 – 4.978)

.045 .005

.009

(0.229)

REF

16 15 14 13 12 11 10 9

.254 MIN

.150 – .165

.229 – .244

.150 – .157**

(5.817 – 6.198)

(3.810 – 3.988)

.0165 .0015

.0250 BSC

RECOMMENDED SOLDER PAD LAYOUT

1

2

3

4

5

6

7

8

.015 .004

(0.38 0.10)

× 45°

.0532 – .0688

(1.35 – 1.75)

.004 – .0098

(0.102 – 0.249)

.007 – .0098

(0.178 – 0.249)

0° – 8° TYP

.016 – .050

(0.406 – 1.270)

.0250

(0.635)

BSC

.008 – .012

GN16 REV B 0212

(0.203 – 0.305)

TYP

NOTE:

1. CONTROLLING DIMENSION: INCHES

INCHES

2. DIMENSIONS ARE IN

(MILLIMETERS)

3. DRAWING NOT TO SCALE

4. PIN 1 CAN BE BEVEL EDGE OR A DIMPLE

*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

2914fc

16

For more information www.linear.com/LTC2914

LTC2914

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

REV

DATE

DESCRIPTION

PAGE NUMBER

B

10/10 Added t and Note 4 to Electrical Characteristics section

4

9-13

2

PW

Updated equations and added Negative Voltage Monitoring Example 2 to Applications Information section

12/13 Corrected LATCH/DIS label in Pin Configuration section

C

2914fc

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.

For more information www.linear.com/LTC2914

17

LTC2914

Typical applicaTion

Quad UV/OV Supply Monitor with LED Undervoltage and Overvoltage Indicator

and Manual Undervoltage Reset Button, ±05 Tolerance, ±2V, .V, 313V, 21.V

12V

5V

3.3V

2.5V

P0WER

SUPPLIES

0.1μF

510Ω

44.2k

1k

V

CC

VH1

SEL

LED

27.4k

VL1

VH2

SYSTEM

OV

4.53k 1k

4.53k 19.6k

LTC2914-1

VL2

UV

REF

VH3

LATCH

1k

2.05M

10k

VL3

VH4

4.53k 100k

VL4

GND TMR

2914 TA06

C

TMR

TIMEOUT = 200ms

22nF

MANUAL

RESET BUTTON

(NORMALLY OPEN)

relaTeD parTs

PART NUMBER

DESCRIPTION

COMMENTS

LTC1326/

Micropower Precision Triple Supply Monitor for 5V/2.5V, 3.3V

and ADJ

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

Adjustable RESET and Watchdog Time-Outs

Individual Monitor Outputs in MSOP

5-Lead SOT-23 Package

LTC1326-2.5

LTC1726-2.5/

LTC1726-5

LTC1727-2.5/

LTC1727-5

LTC1728-1.8/

LTC1728-3.3

LTC1728-2.5/

LTC1728-5

Micropower Triple Supply Monitor for 2.5V/5V, 3.3V and ADJ

Micropower Triple Supply Monitor with Open-Drain Reset

5-Lead SOT-23 Package

LTC1985-1.8

LTC2900

Micropower Triple Supply Monitor with Push-Pull Reset

Programmable Quad Supply Monitor

5-Lead SOT-23 Package

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

Package

LTC2901

LTC2902

Programmable Quad Supply Monitor

Adjustable RESET and Watchdog Timer, 16-Lead SSOP Package

Adjustable RESET and Tolerance, 16-Lead SSOP Package,

Margining Functions

LTC2903

LTC2904

LTC2905

LTC2906

LTC2907

LTC2908

LTC2909

Precision Quad Supply Monitor

6-Lead SOT-23 Package, Ultralow Voltage Reset

Adjustable Tolerance, 8-Lead SOT-23 Package

Adjustable RESET and Tolerance, 8-Lead SOT-23 Package

Three-State Programmable Precision Dual Supply Monitor

Precision Dual Supply Monitor 1 Selectable and 1 Adjustable

Precision Six Supply Monitor

Separate V Pin, RST/RST Outputs

CC

Separate V , Adjustable Reset Timer

CC

8-Lead TSOT-23 and 3mm × 2mm DFN Packages

Precision Dual Input UV, OV and Negative Voltage Monitor

Separate V Pin, Adjustable Reset Timer, 8-Lead TSOT-23 and

CC

3mm × 2mm DFN Packages

2914fc

LT 1213 REV C • PRINTED IN USA

18 ^{LinearTechnology Corporation}

1630 McCarthy Blvd., Milpitas, CA 95035-7417

For more information www.linear.com/LTC2914

●

 LINEAR TECHNOLOGY CORPORATION 2006

(408)432-1900 FAX: (408) 434-0507 www.linear.com/LTC2914


型号：	LTC2914IGN-2#PBF
厂家：	Linear
描述：	LTC2914 - Quad UV/OV Positive/Negative Voltage Monitor; Package: SSOP; Pins: 16; Temperature Range: -40°C to 85°C
文件：	总18页 (文件大小：253K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LTC2914IGN-2#PBF [Linear]

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