Datasheet LX6431IDM, LX6431CLP, LX6431CDM, LX6431BILP, LX6431BIDM Datasheet (Microsemi Corporation)

LX6431/LX6431A/LX6431B

A

P

RECISION PROGRAMMABLE REFERENCES

T HE I NFINITE P OWER OF I NNOVATION

DESCRIPTION KEY FEATURES

The LX6431 series precision adjustable
three terminal shunt voltage regulators are
pin-to-pin compatible with the industry
standard TL431, but with significant
improvements. The LX6431 design has
eliminated regions of instability common
to older generation shunt regulator
products like the TL431. Designs are
made simpler by eliminating the task of
insuring capacitive loads, and output
voltage and cathode currents don't
combine for unstable operation. The
capacitor value is chosen simply to give
the best load transient response without
the possibility of instability. A lower
reference input current allows the use of
higher value reference divider resistors,

NOTE: For current data & package dimensions, visit our web site: http://www.linfinity.com.

OUTPUT VOLTAGE ERROR DUE TO I

reducing the current drain from batteries
in portable equipment as well as reducing
the voltage programming errors due to
the impedance of the divider network
(See Product Highlight figure below). In
addition, the LX6431B has an improved
initial accuracy of 0.4%, and the output
voltage is programmable by using two
external resistors from 2.5V to 36V.

These devices offer low output
impedance for improved load regulation.
The typical output impedance of these
devices is 100mΩ. The reduced
reference input bias current and minimum
operating currents make these devices
suitable for portable and micropower
applications.

PRODUCT HIGHLIGHT

REF

P RODUCTION DATA SHEET

■ Unconditionally Stable For All Cathode To
Anode Capacitance Values

■ Reduced Reference Input Current Allowing
The Use Of Higher Value Divider Resistors
(0.5µA Max.)

■ Initial Voltage Reference Accuracy Of 0.4%
(LX6431B)

■ Sink Current Capability 0.6mA to 100mA

■ Typical Output Dynamic Impedance Less

Than 100mΩ

■ Adjustable Output Voltage From 2.5V to
36V

% Error

20
18

16
14

12
10

TYPICAL PROGRAMMABLE VOLTAGE

REFERENCE CIRCUIT

V

IN

R1

LX6431

8

6
4

2
0

2.5

3.75

5

6.25

7.5

8.75

10

11.25

12.5

(V ) OutputVoltage - (V)

KA

13.75

15

GND

R2

PACKAGE ORDER INFORMATION

(°C)

T

A

0 to 70 1% LX6431ACDM LX6431ACLP

-40 to 85 1% LX6431AIDM LX6431AILP

Initial

Tolerance

2% LX6431CDM LX6431CLP

0.4% LX6431BCDM LX6431BCLP
2% LX6431IDM LX6431ILP

0.4% LX6431BIDM LX6431BILP

Note: All surface-mount packages are available in Tape & Reel.

Append the letter "T" to part number. (i.e. LX5212CDPT)

TO-92 (LP) package also available in ammo-pack.

Plastic SOIC

DM

8-pin

Plastic TO-92

LP

3-pin

V

K

Copyright © 1999
Rev. 1.4 6/99

L INF INITY MICROELECTRONICS INC.

11861 WESTERN AVENUE, GARDEN GROVE, CA. 92841, 714-898-8121, FAX: [phone]

1

PRODUCT DATABOOK 1996/1997

LX6431/LX6431A/LX6431B

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RECISION PROGRAMMABLE REFERENCES

P RODUCTION DATA SHEET

ABSOLUTE MAXIMUM RATINGS (Note 1)

Cathode to Anode Voltage (VKA) ................................................................... -0.3V to 37V

Reference Input Current (I
Continuous Cathode Current (I
Operating Junction Temperature

) .................................................................... -50µA to 10µA

REF

) ......................................................... -100mA to 150mA

K

Plastic (DM & LP Packages) ................................................................................. 150°C

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

Lead Temperature ..................................................................................................... 300°C

Note 1. Exceeding these ratings could cause damage to the device. All voltages are with respect

to Ground. Currents are positive into, negative out of the specified terminal. Pin
numbers refer to DIL packages only.

THERMAL DATA

DM PACKAGE:

THERMAL RESISTANCE-JUNCTION TO AMBIENT,

LP PACKAGE:

THERMAL RESISTANCE-JUNCTION TO AMBIENT,

Junction Temperature Calculation: TJ = TA + (PD x θJA).
The θJA numbers are guidelines for the thermal performance of the device/pc-board system.
All of the above assume no ambient airflow

θθ

θ

θθ

JA

θθ

θ

θθ

JA

165°C/W

156°C/W

BLOCK DIAGRAM

PACKAGE PIN OUTS

CATHODE

N.C.

ANODE

N.C.

1 8
2 7
3 6
4 5

DM PACKAGE

(Top View)

LP PACKAGE

(Top View)

REF
ANODE
ANODE
N.C.

1. CATHODE

2. ANODE

3. REF

Ref (R)

Cathode (K)

V

REF

Anode (A)

2

Copyright © 1999

Rev. 1.4 6/99

PRODUCT DATABOOK 1996/1997

LX6431/LX6431A/LX6431B

P

RECISION PROGRAMMABLE REFERENCES

P RODUCTION DATA SHEET

ELECTRICAL CHARACTERISTICS (Note 2)

(Unless otherwise specified, these specifications apply over the operating ambient temperatures for LX6431C/LX6431AC/LX6431BC with 0°C ≤ TA ≤
70°C, LX6431I/LX6431AI/LX6431BI with -40°C ≤ TA ≤ 85°C.)

Parameter

Reference Input Voltage LX6431 V

LX6431A I
LX6431B IK = 10mA, VKA = V

Reference Drift LX6431 IK = 10mA, VKA = V

LX6431A I

LX6431B IK = 10mA, VKA = V

Symbol

REFIK

= 10mA, VKA = V
= 10mA, VKA = V

K

= 10mA, VKA = V

I

K

= 10mA, VKA = V

K

IK = 10mA, VKA = V

IK = 10mA, VKA = V

Test Conditions

, TA = 25°C,

REF

, TA = 25°C

REF

, TA = 25°C

REF

, 0°C ≤ TA ≤ 70°C

REF

, -40°C ≤ TA ≤ 85°C

REF

, 0°C ≤ TA ≤ 70°C

REF

, -40°C ≤ TA ≤ 85°C

REF

, 0°C ≤ TA ≤ 70°C

REF

, -40°C ≤ TA ≤ 85°C

REF

Voltage Ratio, Reference to Cathode IK = 10mA, VKA = 2.5V to 36V, TA = 25°C

(Note 3) IK = 10mA, VKA = 2.5V to 36V, TA = Operating Range

Reference Input Current I

Minimum Operating Current I

Off-State Cathode Current I
Dynamic Impedance Z

REF

MIN

OFF

KAVKA

VKA = V

, TA = 25°C

REF

VKA = V

, TA = Operating Range

REF

VKA = V

to 36V, TA = 25°C

REF

VKA = V

to 36V, TA = Operating Range

REF

VKA = 36V, V

= V

= 0V, TA = 25°C

REF

, IK = 0.6mA to 100mA, f ≤ 1kHz, TA = 25°C

REF

Note 2. These parameters are guaranteed by design.

∆V

Note 3. Ratio of change in reference input voltage

REF

∆V

KA

to the change in cathode voltage.

LX6431

Min. Typ. Max.

Units

2440 2550 mV
2470 2520 mV
2490 2510 mV

15 mV
25 mV
15 mV
25 mV
15 mV
20 mV

0.3 1 mV/V

0.3 1 mV/V

0.1 0.5 µA

0.1 0.5 µA

0.4 0.6 mA

0.4 0.6 mA

0.3 1 µA
30 100 mΩ

Copyright © 1999
Rev. 1.4 6/99

3

PRODUCT DATABOOK 1996/1997

LX6431/LX6431A/LX6431B

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P RODUCTION DATA SHEET

GRAPH / CURVE INDEX

Characteristic Curves

FIGURE #

1. REFERENCE VOLTAGE vs. FREE-AIR TEMPERATURE

2. REFERENCE CURRENT vs. FREE-AIR TEMPERATURE

3. CATHODE CURRENT vs. CATHODE VOLTAGE

4. OFF-STATE CATHODE CURRENT vs. FREE-AIR TEMPERATURE

5. RATIO OF DELTA REFERENCE VOLTAGE TO DELTA CATHODE

VOLTAGE vs. FREE-AIR TEMPERATURE

6. EQUIVALENT INPUT NOISE VOLTAGE vs. FREQUENCY

FIGURE INDEX

Application Information

FIGURE #

7. COMPARISON OF REFERENCE RESISTOR VALUES BETWEEN AN

LX6431B AND A TL1431. Resistors used with the LX6431B are 5
times higher in value.

8. COMPARISON OF REFERENCE RESISTOR VALUES BETWEEN AN
LX6431B AND A TL1431. When used as 0.5%, 5V shunt
regulators.

Parameter Measurement Information

FIGURE #

9. TEST CIRCUIT FOR V

10. TEST CIRCUIT FOR VKA > V

11. TEST CIRCUIT FOR I

= V

KA

REF

REF

OFF

Typical Characteristics

FIGURE #

12. EQUIVALENT INPUT NOISE VOLTAGE OVER A 10-SECOND PERIOD

13. SMALL-SIGNAL VOLTAGE AMPLIFICATION vs. FREQUENCY

14. REFERENCE IMPEDANCE vs. FREQUENCY

15. PULSE RESPONSE

16. DIFFERENTIAL VOLTAGE AMPLIFICATION vs. FREQUENCY

4

Copyright © 1999

Rev. 1.4 6/99

PRODUCT DATABOOK 1996/1997

0.2

0

(TA) Ambient Temperature - (°C)

0.8

(I

OFF

) Off-State Cathode Current - (µA)

0.4

-50

-25 0

25

50 75 100 125

0.6

VKA = 36V
V

REF

= 0

0.1

0.3

0.5

0.7

LX6431/LX6431A/LX6431B

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P RODUCTION DATA SHEET

CHARACTERISTIC CURVES

FIGURE 1. — REFERENCE VOLTAGE

vs. FREE-AIR TEMPERATURE

2.52

V

= V

REF

KA

IK = 10mA

2.51

2.50

) Reference Voltage - (V)

2.49

REF

(V

2.48

-50

-25 0

25

(TA) Ambient Temperature - (°C)

50 75 100 125

FIGURE 2. — REFERENCE CURRENT

vs. FREE-AIR TEMPERATURE

0.15

IK = 10mA
R1 = 10k

0.14

0.13

0.12



) Reference Current - (µA)

REF

0.11

(I

0.1

-50

-25 0

25

(TA) Ambient Temperature - (°C)

50 75 100 125

FIGURE 3. — CATHODE CURRENT vs. CATHODE VOLTAGE FIGURE 4. — OFF-STATE CATHODE CURRENT

vs. FREE-AIR TEMPERATURE

800

VKA = V

REF

TA = 25°C

600

400

200

) Cathode Current - (µA)

K

(I

0

-200

-1 0

-2

(VKA) Cathode Voltage - (V)

Copyright © 1999
Rev. 1.4 6/99

1

234

5

PRODUCT DATABOOK 1996/1997

120

100

(f) Frequency - (Hz)

260

(V

N

) Noise Voltage - (nV/ Hz)

140

10 100

1k

10k 100k

200

220

160

180

240

IO = 10mA
T

A

= 25°C

LX6431/LX6431A/LX6431B

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P RODUCTION DATA SHEET

CHARACTERISTIC CURVES

FIGURE 5. — RATIO OF DELTA REFERENCE VOLTAGE TO DELTA

CATHODE VOLTAGE vs. FREE-AIR TEMPERATURE

0

VKA = 3V to 36V

-0.1

-0.2

- (mV/V)

KA

-0.3

V

∆

/

REF

V

-0.4

∆

-0.5

-0.6

-50

-25 0

25

50 75 100 125

(TA) Ambient Temperature - (°C)

FIGURE 6. — EQUIVALENT INPUT NOISE VOLTAGE

vs. FREQUENCY

6

Copyright © 1999

Rev. 1.4 6/99

PRODUCT DATABOOK 1996/1997

%

%

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P RODUCTION DATA SHEET

APPLICATION INFORMATION

Application Hints

The reference input current of the LX6431 series voltage refer­ences is much lower than other similar precision parts. This helps
to design programmable voltage references that can use much
higher value programming resistors while maintaining the same
accuracy as the other precision parts. Figure 7 below shows a 5V,
1% shunt regulator using the LX6431B and a shunt regulator using
the TL1431 (Also available from Linfinity). Figure 8 shows 0.5%
shunt regulators. Noteworthy are the values of the reference
resistors used in the two circuits. With the LX6431B it is possible
to use 25k resistors for setting the output voltage with 1%
precision as opposed to 5k programming resistors when the same
precision needs to be achieved with a TL1431.

V

V

IN

25k

R1

0.1%

LX6431B

25k

R2

0.1%

GND

a)

V

IN

5k

R1

0.1%

TL1431

5k

R2

0.1%

GND

b)

FIGURE 7 — Comparison of reference resistor values between an

LX6431B and an TL1431, resistors used with the

LX6431B are 5 times higher in value.

KA

5V, 1

V

KA

5V, 1

LX6431/LX6431A/LX6431B

V

V

IN

1k

R1

0.1%

LX6431B

1k

R2

0.1%

GND

a)

V

IN

240

R1

0.1%

TL1431

240

R2

0.1%

GND

b)

FIGURE 8 — Comparison of reference resistor values between an

LX6431B and a TL1431, when used as 0.5%, 5V shunt regulators.

The output voltage of the reference can be programmed by using
the formula below:

R1

≅∗+

V2.5 1

KA






R2

If more accuracy is required then the effects of the input bias
current (I
accounts for the error this current produces.

) must be taken into account. The formula below

REF

R1

=∗+

V2.5 1

KA REF






R2






Smaller values of programming resistors tend to minimize bias
current errors. In this respect the low input current characteristics
of the LX6431B helps to reduce the power dissipation on the
programming resistors by a factor of five compared to other
references like the TL1431 and TL431.

The LX6431 series of voltage references have an enhanced
circuit design that can tolerate any value of cathode to anode
capacitance.

KA

5V, 0.5%

V

KA

5V, 0.5%






IR1

+∗

Copyright © 1999
Rev. 1.4 6/99

7

PRODUCT DATABOOK 1996/1997

A

A

A

LX6431/LX6431A/LX6431B

P

RECISION PROGRAMMABLE REFERENCES

P RODUCTION DATA SHEET

PARAMETER MEASUREMENT INFORMATION

Input

V

REF

FIGURE 9 — TEST CIRCUIT FOR VKA = V

I

K

Input

V

K

REF

I

Input

R

1

I

REF

R

FIGURE 10 — TEST CIRCUIT FOR VKA > V

V

OFF

V

2

K

REF

I

K

V

K

REF

FIGURE 11 — TEST CIRCUIT FOR I

8

OFF

Copyright © 1999

Rev. 1.4 6/99

PRODUCT DATABOOK 1996/1997

(t)

)

LX6431/LX6431A/LX6431B

P

RECISION PROGRAMMABLE REFERENCES

P RODUCTION DATA SHEET

TYPICAL CHARACTERISTICS

6
5
4

3
2

1
0

-1

-2

-3

) Input Noise Voltage - (µV)

N

-4

(V

-5

-6
0

2

4

f = 0.1 to 10Hz
I

= 10mA

K

= 25°C

T

A

68

10

500µF

Time - (s

FIGURE 12. — EQUIVALENT INPUT NOISE VOLTAGE OVER A 10-SECOND PERIOD

19.1V

1k



V

910

LX6431
(DUT)



2000µF

2000µF

820



16



0.1µF

CC



160k

V

EE

TLE2027
A

= 10V/mV

V

16k

V

CC

1µF

TLE2027



16k



1µF

33k

33k





AV = 2V/V

V

EE

Test Circuit for 0.1Hz to 10Hz Equivalent Input Noise Voltage

1M

2.2µF



CRO

Copyright © 1999
Rev. 1.4 6/99

9

PRODUCT DATABOOK 1996/1997

(f)

)

(f)

)

t

LX6431/LX6431A/LX6431B

P

RECISION PROGRAMMABLE REFERENCES

P RODUCTION DATA SHEET

TYPICAL CHARACTERISTICS

FIGURE 13. — SMALL-SIGNAL VOLTAGE AMPLIFICATION

vs. FREQUENCY

70

IK = 10mA

= 25°C

60

50

T

A

15k

Output

I

K

230





40

30

20

10

) Voltage Amplification - (dB)

V

(A

0

-10
1k 100k

10k 1M

Frequency - (Hz

FIGURE 14. — REFERENCE IMPEDANCE vs. FREQUENCY

100

)



IK = 1mA to 100mA
T

= 25°C

A

10

10M

9µF

8.25k



Test Circuit for Voltage Amplification

1k



50



GND

Outpu

I

K

10

1

|) Reference Impedance - (

KA

(|z

0.1
1k 100k

10k

Frequency - (Hz

GND

1M 10M

Test Circuit for Reference Impedance

Copyright © 1999

Rev. 1.4 6/99

PRODUCT DATABOOK 1996/1997

t

FIGURE 15. — PULSE RESPONSE

6

5

4

- (V)

3

IN

V

2
1

0

LX6431/LX6431A/LX6431B

P

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P RODUCTION DATA SHEET

TYPICAL CHARACTERISTICS

Pulse

Generator

f = 100kHz

220





50

Outpu

3

)

2

KA

(V

1
0

Output Voltage - (V)

05

2134

(t) Time - (µs)

FIGURE 16. — DIFFERENTIAL VOLTAGE AMPLIFICATION

vs. FREQUENCY

50

30

10

0

-10

Phase Shift

GM/20

GND

Test Circuit for Pulse Response

6

180

10X Probe

+35V

C

10µF

R3

1K

R1
100K

1

R2
100K

C

10µF

2

To Network
Analyzer as
DUT Output Port

R4



2

90

0

-90

To Network

Analyzer as DUT

Input Port with

Phase Shift

- Differential Voltage Amplification - (dB)

VD

A

Copyright © 1999
Rev. 1.4 6/99

-30

-50
1k 10k 100k 1M

Frequency - (Hz)

PRODUCTION DATA - Information contained in this document is proprietary to LinFinity, and is current as of publication date. This document
may not be modified in any way without the express written consent of LinFinity. Product processing does not necessarily include testing of
all parameters. Linfinity reserves the right to change the configuration and performance of the product and to discontinue product at any time.

-180

DUT is bias at 30mA and 5V

Test Setup for Measuring AVD vs. Frequency

11