LTC6652AHMS8-3.3-PBF

LTC6652

Precision Low Drift

Low Noise

Buffered Reference

FEATURES

DESCRIPTION

The LTC^®6652 family of precision, low drift, low noise

references is fully speciﬁed over the temperature range

of –40°C to 125°C. High order curvature compensation

allows these references to achieve a low drift of less than

5ppm/°Cwithapredictabletemperaturecharacteristicand

an output voltage accuracy of 0.05ꢀ. The performance

over temperature should appeal to automotive, high-

performance industrial and other high temperature

applications.

n

Low Drift: A Grade 5ppm/°C Max

B Grade 10ppm/°C Max

n

High Accuracy: A Grade 0ꢀ05ꢁ% B Grade 0ꢀ1ꢁ

n

Low Noise: 2ꢀ1ppm (0ꢀ1Hz to 10Hz)

p-p

n

100ꢁ Tested at –40°C% 25°C and 125°C

n

Sinks and Sources Current: 5mA

n

Low Power Shutdown: <2μA Maximum

n

Thermal Hysteresis: 105ppm for –40°C to 125°C

Range

n

Low Dropout: 300mV

The LTC6652 voltage references can be powered from a

13.2Vsupplyoraslittleas300mVabovetheoutputvoltage

or 2.7V; whichever is higher. The LTC6652 references

are offered in an 8-Lead MSOP package. They boast low

noise, excellentloadregulation, sourceandsinkcapability

and exceptional line rejection, making them a superior

choice for demanding precision applications. A shutdown

mode allows power consumption to be reduced when the

reference is not needed. The optional output capacitor can

be left off when space constraints are critical.

n

No External Load Capacitor Required

n

Wide Supply Range to 13.2V

n

Available Output Voltage Options: 1.25V, 2.048V,

2.5V, 3V, 3.3V, 4.096V, 5V

8-Lead MSOP Package

n

APPLICATIONS

n

Automotive Control and Monitoring

n

High Temperature Industrial

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

All other trademarks are the property of their respective owners.

n

High Resolution Data Acquisition Systems

Instrumentation and Process Control

Precision Regulators

Medical Equipment

n

TYPICAL APPLICATION

Output Voltage Temperature Drift

0.050

Basic Connection

0.025

0

V

OUT

V

OUT

LTC6652-2.5

GND

2.8V b V b 13.2V

IN

2.5V

C

OUT

C

IN

SHDN

1MF

0.1MF

(OPTIONAL)

6652 TA01a

–0.025

–0.050

–40 –20

0

20 40 60 80 100 125

TEMPERATURE (°C)

6652 TA01b

6652fb

1

LTC6652

ABSOLUTE MAXIMUM RATINGS

PIN CONFIGURATION

(Note 1)

TOP VIEW

Input Voltage

DNC

IN

SHDN

GND

1

2

3

4

8 GND*

7 GND*

V to GND..........................................–0.3V to 13.2V

IN

V

SHDN to GND ............................–0.3V to (V + 0.3V)

IN

6 V

OUT

5 GND*

Output Voltage

V

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

MS8 PACKAGE

8-LEAD PLASTIC MSOP

= 150°C, θ = 200°C/W

OUT

IN

Output Short-Circuit Duration...................... Indeﬁnite

Operating Temperature Range................ –40°C to 125°C

Storage Temperature Range (Note 2) ..... –65°C to 150°C

Lead Temperature Range (Soldering, 10 sec)

T

JMAX

JA

DNC: DO NOT CONNECT

*CONNECT THE PINS TO DEVICE GND (PIN 4)

(Note 9)............................................................. 300°C

ORDER INFORMATION

LEAD FREE FINISH

TAPE AND REEL

PART MARKING*

LTCVH

LTCVJ

LTCQV

LTCVK

LTCVM

LTCVN

LTCVP

PACKAGE DESCRIPTION

8-Lead Plastic MSOP

TEMPERATURE RANGE

LTC6652AHMS8-1.25#PBF

LTC6652BHMS8-1.25#PBF

LTC6652AHMS8-2.048#PBF

LTC6652BHMS8-2.048#PBF

LTC6652AHMS8-2.5#PBF

LTC6652BHMS8-2.5#PBF

LTC6652AHMS8-3#PBF

LTC6652BHMS8-3#PBF

LTC6652AHMS8-3.3#PBF

LTC6652BHMS8-3.3#PBF

LTC6652AHMS8-4.096#PBF

LTC6652BHMS8-4.096#PBF

LTC6652AHMS8-5#PBF

LTC6652BHMS8-5#PBF

LTC6652AHMS8-1.25#TRPBF

LTC6652BHMS8-1.25#TRPBF

LTC6652AHMS8-2.048#TRPBF

LTC6652BHMS8-2.048#TRPBF

LTC6652AHMS8-2.5#TRPBF

LTC6652BHMS8-2.5#TRPBF

LTC6652AHMS8-3#TRPBF

LTC6652BHMS8-3#TRPBF

LTC6652AHMS8-3.3#TRPBF

LTC6652BHMS8-3.3#TRPBF

LTC6652AHMS8-4.096#TRPBF

LTC6652BHMS8-4.096#TRPBF

LTC6652AHMS8-5#TRPBF

LTC6652BHMS8-5#TRPBF

–40°C to 125°C

LTCVP

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/

AVAILABLE OPTIONS

OUTPUT VOLTAGE

INITIAL ACCURACY

TEMPERATURE COEFFICIENT

PART NUMBER**

1.250

0.05ꢀ

0.1ꢀ

5ppm/°C

10ppm/°C

LTC6652AHMS8-1.25

LTC6652BHMS8-1.25

2.048

2.500

3.000

3.300

4.096

5.000

0.05ꢀ

0.1ꢀ

0.05ꢀ

0.1ꢀ

0.05ꢀ

0.1ꢀ

0.05ꢀ

0.1ꢀ

0.05ꢀ

0.1ꢀ

0.05ꢀ

0.1ꢀ

5ppm/°C

LTC6652AHMS8-2.048

LTC6652BHMS8-2.048

LTC6652AHMS8-2.5

LTC6652BHMS8-2.5

LTC6652AHMS8-3

LTC6652BHMS8-3

LTC6652AHMS8-3.3

LTC6652BHMS8-3.3

LTC6652AHMS8-4.096

LTC6652BHMS8-4.096

LTC6652AHMS8-5

LTC6652BHMS8-5

10ppm/°C

5ppm/°C

10ppm/°C

5ppm/°C

10ppm/°C

5ppm/°C

10ppm/°C

5ppm/°C

10ppm/°C

5ppm/°C

10ppm/°C

**See Order Information section for complete part number listing.

6652fb

2

LTC6652

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

temperature range% otherwise speciﬁcations are at T_A= 25°C% V_IN= V_OUT+ 0ꢀ5V% unless otherwise notedꢀ

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Output Voltage

LTC6652A

LTC6652B

–0.05

–0.1

0.05

0.1

ꢀ

l

Output Voltage Temperature Coefﬁcient

(Note 3)

LTC6652A

LTC6652B

2

4

5

10

ppm/°C

Line Regulation

V

+ 0.5V ≤ V ≤ 13.2V, SHDN = V

IN

2

50

80

ppm/V

OUT

IN

l

Load Regulation (Note 4)

I

= 5mA, LTC6652-1.25, LTC6652-2.048,

20

75

200

ppm/mA

SOURCE

LTC6652-2.5, LTC6652-3, LTC6652-3.3, LTC6652-

4.096, LTC6652-5

I

= 1mA, LTC6652-1.25, LTC6652-2.048

80

50

250

600

ppm/mA

SINK

l

I

= 5mA, LTC6652-2.5, LTC6652-3,

150

450

ppm/mA

SINK

LTC6652-3.3, LTC6652-4.096, LTC6652-5

= 5mA, V Error ≤ 0.1ꢀ

Minimum Operating Voltage (Note 5)

I

SOURCE

OUT

l

LTC6652-1.25, LTC6652-2.048

LTC6652-2.5, LTC6652-3, LTC6652-3.3,

LTC6652-4.096, LTC6652-5

2.7

OUT

V

+ 0.3V

Output Short-Circuit Current

Short V

to GND

16

mA

OUT

to V

IN

l

Shutdown Pin (SHDN)

Logic High Input Voltage

Logic High Input Current

2

V

μA

0.1

1

l

Logic Low Input Voltage

Logic Low Input Current

0.8

1

V

μA

0.1

Supply Current

No Load

350

μA

l

560

2

Shutdown Current

SHDN Tied to GND

0.1

μA

Output Voltage Noise (Note 6)

0.1Hz ≤ f ≤ 10Hz

LTC6652-1.25

2.4

2.1

2.2

2.3

2.8

3

ppm

P-P

LTC6652-2.048, LTC6652-2.5, LTC6652-3

LTC6652-3.3

LTC6652-4.096

LTC6652-5

10Hz ≤ f ≤ 1kHz

ppm

RMS

Turn-On Time

0.1ꢀ Settling, C

= 0

100

60

μs

LOAD

Long Term Drift of Output Voltage (Note 7)

Hysteresis (Note 8)

ppm/√khr

Δ = –40°C to 125°C

T

105

ppm

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: If the parts are stored outside of the speciﬁed temperature range,

the output may shift due to hysteresis.

Note 3: Temperature coefﬁcient is measured by dividing the maximum

change in output voltage by the speciﬁed temperature range.

Note 4: Load regulation is measured on a pulse basis from no load to the

speciﬁed load current. Output changes due to die temperature change

must be taken into account separately.

removed to determine the actual noise of the device.

Note 7: Long term stability typically has a logarithmic characteristic and

therefore, changes after 1000 hours tend to be much smaller than before that

time. Total drift in the second thousand hours is normally less than one third

that of the ﬁrst thousand hours with a continuing trend toward reduced drift

with time. Long-term stability will also be affected by differential stresses

between the IC and the board material created during board assembly.

Note 8: Hysteresis in output voltage is created by package stress that differs

depending on whether the IC was previously at a higher or lower temperature.

Output voltage is always measured at 25°C, but the IC is cycled to the hot

or cold temperature limit before successive measurements. Hysteresis

is roughly proportional to the square of the temperature change. For

instruments that are stored at well controlled temperatures (within 20 or 30

degrees of operational temperature) it’s usually not a dominant error source.

Note 5: Excludes load regulation errors.

Note 6: Peak-to-peak noise is measured with a 3-pole highpass at 0.1Hz

and 4-pole lowpass ﬁlter at 10Hz. The unit is enclosed in a still-air

environment to eliminate thermocouple effects on the leads. The test

time is 10 seconds. RMS noise is measured on a spectrum analyzer in

a shielded environment where the intrinsic noise of the instrument is

Note 9: The stated temperature is typical for soldering of the leads during

manual rework. For detailed IR reﬂow recommendations, refer to the

Applications section.

6652fb

3

LTC6652

TYPICAL PERFORMANCE CHARACTERISTICS

Characteristic curves are similar for most

LTC6652sꢀ Curves from the LTC6652-1ꢀ25% LTC6652-2ꢀ5 and the LTC6652-5 represent the extremes and typical of the voltage optionsꢀ

Characteristic curves for other output voltages fall between these curves and can be estimated based on their outputꢀ

1ꢀ25V Output Voltage

Temperature Drift

1ꢀ25V Line Regulation

1ꢀ25V Load Regulation (Sourcing)

1.2510

1.2505

1.2500

1.2495

1.2490

1.2506

1.2504

1.2502

1.2500

0

–50

3 TYPICAL PARTS

–40oC

125°C

25oC

–100

–150

–200

–250

125oC

25°C

1.2498

1.2496

1.2494

–40°C

10

80

TEMPERATURE (°C)

–80

–40

0

40

120

160

8

12

14

0

2

4

6

0.1

1

10

INPUT VOLTAGE (V)

OUTPUT CURRENT (mA)

6652 G17

6652 G18

6652 G19

1ꢀ25V Low Frequency 0ꢀ1Hz to

10Hz Transient Noise

1ꢀ25V Output Voltage Noise

Spectrum

1ꢀ25V Load Regulation (Sinking)

400

350

300

250

200

150

100

50

400

300

200

100

0

125°C

25°C

–40°C

0

0.1

1

10

TIME (1 SECOND/DIV)

0.01

0.1

1

10

OUTPUT CURRENT (mA)

FREQUENCY (kHz)

6652 G22

6652 G20

6652 G21

1ꢀ25 Sinking Current Without

Output Capacitor

1ꢀ25 Sinking Current with Output

Capacitor

1ꢀ25V Stability with Output

Capacitance

10μF

1μF

1mA

0mA

1mA

0mA

I

OUT

0.1μF

10nF

V

OUT

500mV/DIV

REGION OF

MARGINAL

STABILITY

OUT

500mV/DIV

1nF

100pF

6652 G23

6652 G24

500μs/DIV

C

= 0μF

C

= 1μF

OUT

NO CAP

–5

–1

0

5

LOAD CURRENT (mA)

6652 G16

6652fb

4

LTC6652

TYPICAL PERFORMANCE CHARACTERISTICS

Characteristic curves are similar for most

LTC6652sꢀ Curves from the LTC6652-1ꢀ25% LTC6652-2ꢀ5 and the LTC6652-5 represent the extremes and typical of the voltage optionsꢀ

Characteristic curves for other output voltages fall between these curves and can be estimated based on their outputꢀ

2ꢀ5V Output Voltage

Temperature Drift

2ꢀ5V Line Regulation

2ꢀ5V Load Regulation (Sourcing)

0

–20

2.5010

2.5005

2.5000

2.4995

2.4990

2.4985

2.5010

2.5005

2.5000

2.4995

3 TYPICAL PARTS

–40°C

–40

–60

125°C

25°C

–80

125°C

–100

–120

–140

–160

–180

–200

–40°C

2.4990

2.4985

2.4980

50

0.1

1

10

–50 –25

0

25

75 100 125 150

8

12

14

0

2

4

6

10

OUTPUT CURRENT (mA)

TEMPERATURE (°C)

INPUT VOLTAGE (V)

6652 G01

6652 G03

6652 G02

2ꢀ5V Supply Current

vs Input Voltage

2ꢀ5V Shutdown Current

vs Input Voltage

2ꢀ5V Load Regulation (Sinking)

1000

900

800

700

600

500

400

300

200

100

0

700

600

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

500

400

125°C

25°C

125°C

25°C

200

100

0

–40°C

25°C

–40°C

0

4

6

8

10

12

14

0.1

1

10

2

0

4

6

8

10

12

14

2

INPUT VOLTAGE (V)

OUTPUT CURRENT (mA)

INPUT VOLTAGE (V)

6652 G05

6652 G04

6652 G06

2ꢀ5V Minimum V_IN-V_OUT

Differential (Sourcing)

2ꢀ5V Minimum V_OUT-V_IN

Differential (Sinking)

10

1

25°C

0.1

0.01

25°C

125°C, –40°C

125°C

–40°C

0.1

0.001

0.01

0.1

1

0.001

0.01

0.1

1

OUTPUT-INPUT VOLTAGE (V)

INPUT-OUTPUT VOLTAGE (V)

6652 G10

6652 G09

6652fb

5

LTC6652

TYPICAL PERFORMANCE CHARACTERISTICS

Characteristic curves are similar for most

LTC6652sꢀ Curves from the LTC6652-1ꢀ25% LTC6652-2ꢀ5 and the LTC6652-5 represent the extremes and typical of the voltage optionsꢀ

Characteristic curves for other output voltages fall between these curves and can be estimated based on their outputꢀ

2ꢀ5V Low Frequency 0ꢀ1Hz to

10Hz Transient Noise

2ꢀ5V Output Voltage Noise

Spectrum

600

500

400

300

200

100

0

TIME (1 SECOND/DIV)

0.01

0.1

1

10

FREQUENCY (kHz)

6652 G12

6652 G11

Stability with Output Capacitance

(LTC6652-2ꢀ5% LTC6652-3%

LTC6652-3ꢀ3% LTC6652-4ꢀ906%

LTC6652-5)

Typical V_OUTDistribution for

LTC6652-2ꢀ5

180

160

140

120

80

10μF

1μF

1004 UNITS

LTC6652A LIMITS

0.1μF

10nF

REGION OF

MARGINAL STABILITY

60

1nF

100pF

40

20

0

NO CAP

2.4985

2.4995

2.5005

2.5015

–5

0

5

OUTPUT VOLTAGE (V)

LOAD CURRENT (mA)

6652 G15

6652 G14

6652fb

6

LTC6652

TYPICAL PERFORMANCE CHARACTERISTICS

Characteristic curves are similar for most

LTC6652sꢀ Curves from the LTC6652-1ꢀ25% LTC6652-2ꢀ5 and the LTC6652-5 represent the extremes and typical of the voltage optionsꢀ

Characteristic curves for other output voltages fall between these curves and can be estimated based on their outputꢀ

5V Output Voltage

Temperature Drift

5V Supply Current

vs Input Voltage

5V Line Regulation

5.005

5.003

5.000

4.998

4.995

5.002

5.001

5.000

4.999

4.998

1000

900

800

700

600

500

400

300

200

100

0

3 TYPICAL PARTS

25°C

125°C

–40°C

125°C

25°C

–40°C

50

0

2

4

6

8

10

12

14

–50 –25

0

25

75 100 125 150

0

4

6

8

10

12

14

2

TEMPERATURE (°C)

INPUT VOLTAGE (V)

6652 G25

6652 G26

6652 G27

5V Shutdown Current

vs Input Voltage

5V Minimum V_INto V_OUT

Differential (Sourcing)

5V Low Frequency 0ꢀ1Hz to 10Hz

Transient Noise

10

1

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

125°C

25°C

0.1

0.01

–40°C

125°C

25°C

10

12

INPUT VOLTAGE (V)

0.001

0.01

0.1

1

0

4

6

8

14

TIME (1 SECOND/DIV)

2

INPUT-OUTPUT VOLTAGE (V)

6652 G30

6652 G31

6652 G29

5V Start-Up Response Without

Output Capacitor

5V Start-Up Response with Output

Capacitor

5V Output Voltage Noise Spectrum

1000

800

600

400

200

0

V

IN

2V/DIV

V

OUT

2V/DIV

OUT

2V/DIV

6652 G33

6652 G34

100μs/DIV

C

= 0μF

C

= 1μF

OUT

0.01

0.1

1

10

FREQUENCY (kHz)

6652 G32

6652fb

7

LTC6652

TYPICAL PERFORMANCE CHARACTERISTICS

Characteristic curves are similar for most

LTC6652sꢀ Curves from the LTC6652-1ꢀ25% LTC6652-2ꢀ5 and the LTC6652-5 represent the extremes and typical of the voltage optionsꢀ

Characteristic curves for other output voltages fall between these curves and can be estimated based on their outputꢀ

Power Supply Rejection Ratio

vs Frequency

SHDN Input Voltage Thresholds

Output Impedance vs Frequency

vs V_IN

100

0

–10

–20

–30

2.5

2.0

1.5

1.0

0.5

0

C

OUT

= 0μF

C

OUT

= 0μF

V

TH(UP)

10

1

C

OUT

= 1μF

–40

–50

V

TH(DN)

C

OUT

= 1μF

C

OUT

= 10μF

–60

–70

C

OUT

= 10μF

–80

–90

0.1

–100

8

12

14

0.01

0.1

1

10

100

1000

0.01

0.1

1

10

100

2

4

6

10

FREQUENCY (kHz)

V

IN

(V)

6652 G13

6652 G08

6652 G07

PIN FUNCTIONS

DNC (Pin 1): Do Not Connect.

GND (Pin 4): Device Ground.

(Pin 6): Output Voltage. An output capacitor is not

required.Forsomeapplications,acapacitorbetween0.1μF

to 10μF can be beneﬁcial. See the graphs in the Typical

Performance Characteristics section for further details.

V (Pin 2): Power Supply. The minimum supply input is

V

OUT

IN

OUT

V

+300mVor2.7V;whicheverishigher.Themaximum

supply is 13.2V. Bypassing V with a 0.1μF capacitor to

GND will improve PSRR.

IN

SHDN (Pin 3): Shutdown Input. This active low input

GND (Pins 5%7%8): Internal function. Ground these pins.

powers down the device to <2μA. For normal operation

tie this pin to V .

IN

6652fb

8

LTC6652

BLOCK DIAGRAM

V

IN

2

+

–

V

OUT

SHDN

BANDGAP

3

6

GND

4

6652 BD

APPLICATIONS INFORMATION

Bypass and Load Capacitors

The LTC6652 references with an output of 2.5V and above

are guaranteed to source and sink 5mA. The 1.25V and

2.048V versions are guaranteed to source 5mA and sink

1mA. The test circuit for transient load step response is

shown in Figure 1. Figures 4 and 5 show a 5mA source

and sink load step response without a load capacitor,

respectively.

The LTC6652 voltage references do not require an input

capacitor, but a 0.1μF capacitor located close to the part

improves power supply rejection.

The LTC6652 voltage references are stable with or without

acapacitiveload. Forapplicationswhereanoutputcapaci-

tor is beneﬁcial, a value of 0.1μF to 10μF is recommended

depending on load conditions. The Typical Performance

Characteristics section includes a plot illustrating a region

of marginal stability. Either no or low value capacitors for

anyloadcurrentareacceptable. Forloadsthatsinkcurrent

orlightloadsthatsourcecurrent,a0.1μFto10μFcapacitor

has stable operation. For heavier loads that source current

a 0.5μF to 10μF capacitor range is recommended.

Start-Up

The start-up characteristic of the LTC6652 is shown in

Figures 8 and 9. Note that the turn-on time is affected by

the value of the output capacitor.

100Ω

2, 3

6

V

IN

LTC6652-2.5

3V

C

IN

C

The transient response for a 0.5V step on V with and

OUT

1μF

IN

0.5V

V

GEN

0.1μF

without an output capacitor is shown in Figures 2 and 3,

4, 5, 7, 8

6652 F01

respectively.

Figure 1ꢀ Transient Load Test Circuit

6652fb

9

LTC6652

APPLICATIONS INFORMATION

3.5V

5mA

0mA

V

IN

I

3V

OUT

V

OUT

500mV/DIV

V

OUT

200mV/DIV

6652 F05

6652 F02

C

OUT

= 0μF

250μs/DIV

C

= 0μF

500μs/DIV

OUT

Figure 2ꢀ Transient Response Without Output Capacitor

Figure 5ꢀ LTC6652-2ꢀ5 Sinking

Current Without Output Capacitor

0mA

3.5V

I

OUT

V

IN

–5mA

3V

V

OUT

500mV/DIV

V

OUT

200mV/DIV

6652 F03

6652 F06

C

= 1μF

500μs/DIV

C

OUT

= 1μF

250μs/DIV

OUT

Figure 6ꢀ LTC6652-2ꢀ5 Sourcing Current

with Output Capacitor

Figure 3ꢀ Transient Response with 1μF Output Capacitor

5mA

0mA

I

OUT

0mA

–5mA

V

OUT

V

OUT

50mV/DIV

200mV/DIV

6652 F07

6652 F04

C

OUT

= 1μF

250μs/DIV

C

= 0μF

250μs/DIV

OUT

Figure 7ꢀ LTC6652-2ꢀ5 Sinking

Current with Output Capacitor

Figure 4ꢀ LTC6652-2ꢀ5 Sourcing

Current Without Output Capacitor

6652fb

10

LTC6652

APPLICATIONS INFORMATION

2.8V b V b 13.2V

IN

C1

1μF

R1

20k

V

IN

2V/DIV

V

IN

LTC6652-2.5

SHDN

V

OUT

V

OUT

GND

V

TO μC

6652 F10

OUT

C2

1μF

2N7002

1V/DIV

Figure 10ꢀ Open-Drain Shutdown Circuit

6652 F08

C

= 0μF

100μs/DIV

OUT

Figure 8ꢀ Start-Up Response Without Output Capacitor

SHDN

1V/DIV

V

IN

2V/DIV

V

OUT

1V/DIV

V

OUT

1V/DIV

6652 F11

I

= 5mA

1ms/DIV

LOAD

6652 F09

Figure 11ꢀ Shutdown Response with 5mA Load

C

= 1μF

100μs/DIV

OUT

Figure 9ꢀ Start-Up Response with 1μF Output Capacitor

The trip thresholds on SHDN have some dependence

on the voltage applied to V as shown in the Typical

IN

InFigure8,ripplemomentarilyappearsjustaftertheleading

edge of powering on. This brief one time event is caused

bycalibrationcircuitryduringinitialization.Whenanoutput

capacitor is used, the ripple is virtually undetectable as

shown in Figure 9.

Performance Characteristics section. Be careful to avoid

leaving SHDN at a voltage between the thresholds as

this will likely cause an increase in supply current due to

shoot-through current.

Long-Term Drift

Shutdown Mode

Long-term drift cannot be extrapolated from acceler-

atedhightemperaturetestingꢀThiserroneoustechnique

gives drift numbers that are wildly optimisticꢀ The only

way long-term drift can be determined is to measure it

overthetimeintervalofinterestꢀTheLTC6652long-term

drift data was collected on more than 100 parts that were

solderedintoPCboardssimilartoa“realworld”application.

The boards were then placed into a constant temperature

ShutdownmodeisenabledbytyingSHDNlowwhichplaces

the part in a low power state (i.e., <2μA). In shutdown

mode, the output pin takes the value 20k • (rated output

voltage). For example, an LTC6652-2.5 will have an output

impedance of 20k • 2.5 = 50kΩ. For normal operation,

SHDN should be greater than or equal to 2.0V. For use

with a microcontroller, use a pull-up resistor to V and

IN

an open-drain output driver as shown in Figure 10. The

LTC6652’s response into and out of shutdown mode is

shown in Figure 11.

oven with T = 35°C, their outputs were scanned regularly

A

and measured with an 8.5 digit DVM. Long-term drift is

shown below in Figure 12.

6652fb

11

LTC6652

APPLICATIONS INFORMATION

80

35

30

25

20

15

10

5

LTC6652-2.5 MS8 PACKAGE

3 TYPICAL PARTS

125°C TO 25°C

–40°C TO 25°C

T

= 35oC

60

40

A

20

0

–20

–40

0

300

600

900

1200

1500

–250

–150

–50

50

150

HOURS

DISTRIBUTION (ppm)

6652 F12

6652 F13

Figure 12ꢀ Long Term Drift

Figure 13ꢀ Hysteresis Plot –40°C to 125°C

Hysteresis

IR Reﬂow Shift

The hysteresis data shown in Figure 13 represents the

worst-case data collected on parts from –40°C to 125°C.

The output is capable of dissipating relatively high power,

Thedifferentexpansionandcontractionratesofthemateri-

als that make up the lead-free LTC6652 package cause the

output voltage to shift after undergoing IR reﬂow. Lead-

free reﬂow proﬁles reach over 250°C, considerably more

than their leaded counterparts. The lead-free IR reﬂow

proﬁle used to experimentally measure output voltage

shift in the LTC6652-2.5 is shown in Figure 14. Similar

results can be expected using a convection reﬂow oven.

In our experiment, the serialized parts were run through

the reﬂow process twice. The results indicate that the

standard deviation of the output voltage increases with a

slight positive mean shift of 0.003ꢀ as shown in Figure

15. While there can be up to 0.016ꢀ of output voltage

shift, the overall drift of the LTC6652 after IR reﬂow does

not vary signiﬁcantly.

i.e., for the LT6652-2.5, P = 10.7V • 5.5mA = 58.85mW.

D

ThethermalresistanceoftheMS8packageis200°C/Wand

this dissipation causes a 11.8°C internal rise. This could

increase the junction temperature above 125°C and may

cause the output to shift due to thermal hysteresis.

PC Board Layout

The mechanical stress of soldering a surface mount volt-

age reference to a PC board can cause the output voltage

to shift and temperature coefﬁcient to change. These two

changes are not correlated. For example, the voltage may

shift, but the temperature coefﬁcient may not.

To reduce the effects of stress-related shifts, mount the

reference near the short edge of the PC board or in a

corner. In addition, slots can be cut into the board on two

sides of the device.

Power Dissipation

Power dissipation in the LTC6652 is dependent on V ,

IN

load current, and package. The LTC6652 package has

a thermal resistance, or θ , of 200°C/W. A curve that

JA

The capacitors should be mounted close to the package.

illustrates allowed power dissipation vs temperature for

The GND and V

traces should be as short as possible

this package is shown in Figure 16.

OUT

to minimize I • R drops. Excessive trace resistance directly

impacts load regulation.

The power dissipation of the LTC6652-2.5V as a function

of input voltage is shown in Figure 17. The top curve

showspowerdissipationwitha5mAloadandthebottom

6652fb

12

LTC6652

APPLICATIONS INFORMATION

curve shows power dissipation with no load.

rent will be slightly higher and the power consumption

increases to just over 60mW. The power-derating curve

in Figure 16 shows the LTC6652-2.5 can safely dissipate

125mW at 125°C about half the maximum power con-

sumption of the package.

When operated within its speciﬁed limits of V = 13.2V

IN

andsourcing5mA,theLTC6652-2.5consumesjustunder

60mW at room temperature. At 125°C the quiescent cur-

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

300

380s

T

= 260°C

P

RAMP

DOWN

T

= 217°C

L

225

150

75

T

= 200°C

S(MAX)

t

T

= 190°C

P

S

30s

T = 150°C

t

L

RAMP TO

150°C

130s

40s

120s

4

0

20

40

60

140

0

2

6

8

10

80 100 120

MINUTES

TEMPERATURE (°C)

6652 F16

6652 F14

Figure 14ꢀ Lead-Free Reﬂow Proﬁle

Figure 16ꢀ Maximum Recommended Dissipation for LTC6652

10

0.06

T

= 25°C

A

0.05

0.04

0.03

0.02

0.01

0

8

6

4

2

0

5mA LOAD

NO LOAD

–0.014 –0.006

0.002

0.010

0.018

2

4

6

8

14

10

12

OUTPUT VOLTAGE SHIFT DUE TO IR REFLOW (ꢀ)

V

IN

(V)

6652 F17

6652 F15

Figure 17ꢀ Typical Power Dissipation of the LTC6652

Figure 15ꢀ Output Voltage Shift Due to IR Reﬂow

6652fb

13

LTC6652

TYPICAL APPLICATIONS

Extended Supply Range Reference

6V TO 160V

4V TO 30V

R1

330k

R2

4.7k

ON SEMI

R1

MMBT5551

V

OUT

V

OUT

LTC6652-2.5

GND

IN

V

IN

SHDN

C1

0.1μF

BZX84C18

C2

OPTIONAL

6652 TA02

V

LTC6652-2.5

GND

OUT

BZX84C18

C2

OPTIONAL

C1

0.1μF

6652 TA03

Negative Rail Circuit

Boosted Output Current

+

V

r (V

+ 1.8V)

OUT

R1

2207

C1

1μF

2, 3, 6

LTC6652-2.5

2N2905

V

SHDN

IN

6652 TA06

4, 5, 7, 8

100Ω

–3.5V

V

OUT

–2.5V

1μF

V

OUT

LTC6652-2.5

GND

C2

1μF

6652 TA04

6652fb

14

LTC6652

PACKAGE DESCRIPTION

MS8 Package

8-Lead Plastic MSOP

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

0.889 ± 0.127

(.035 ± .005)

5.23

(.206)

MIN

3.20 – 3.45

(.126 – .136)

3.00 ± 0.102

(.118 ± .004)

(NOTE 3)

0.52

(.0205)

REF

0.65

(.0256)

BSC

0.42 ± 0.038

(.0165 ± .0015)

TYP

8

7 6 5

RECOMMENDED SOLDER PAD LAYOUT

3.00 ± 0.102

(.118 ± .004)

(NOTE 4)

4.90 ± 0.152

(.193 ± .006)

DETAIL “A”

0.254

(.010)

0° – 6° TYP

GAUGE PLANE

1

2

3

4

0.53 ± 0.152

(.021 ± .006)

1.10

(.043)

MAX

0.86

(.034)

REF

DETAIL “A”

0.18

(.007)

SEATING

PLANE

0.22 – 0.38

0.1016 ± 0.0508

(.009 – .015)

(.004 ± .002)

0.65

(.0256)

BSC

TYP

MSOP (MS8) 0307 REV F

NOTE:

1. DIMENSIONS IN MILLIMETER/(INCH)

2. DRAWING NOT TO SCALE

3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.

MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE

4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.

INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE

5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX

6652fb

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.

15

LTC6652

TYPICAL APPLICATION

Improved Reference Supply Rejection in a Data Converter Application

LTC1657

16

D/A

REF

DATA

VDAC

V

CC

GND

V

IN

R1

50k

V

OUT

LTC6652

REF

A/D

LTC1605

SHDN

V1

16

C1

0.1μF

V2

V3

V4

D

OUT

C2

C

OUT

10μF

1μF

GND

6652 TA05

RELATED PARTS

PART NUMBER DESCRIPTION

COMMENTS

LT1460

LT1461

LT1790

LT6650

LT6660

Micropower Series References

Micropower Series Low Dropout

Micropower Precision Series References

0.075ꢀ Max, 10ppm/°C Max, 20mA Output Current

0.04ꢀ Max, 3ppm/°C Max, 50mA Output Current

0.05ꢀ Max, 10ppm/°C Max, 60μA Supply, SOT23 Package

0.5ꢀ Max, 5.6μA Supply, SOT23 Package

Micropower Reference with Buffer Ampliﬁer

Tiny Micropower Series Reference

0.2ꢀ Max, 20ppm/°C Max, 20mA Output Current, 2mm × 2mm DFN

6652fb

LT 1208 REV B • PRINTED IN USA

LinearTechnology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

16

●

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


型号：	LTC6652AHMS8-3.3-PBF
厂家：	Linear
描述：	Precision Low Drift Low Noise Buffered Reference 精密，低漂移，低噪声缓冲基准
文件：	总16页 (文件大小：332K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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