LM431CCMX - National Semiconductor

LM431

Adjustable Precision Zener Shunt Regulator

General Description

The LM431 is a 3-terminal adjustable shunt regulator with

guaranteed temperature stability over the entire temperature

range of operation. It is now available in a chip sized pack-

age (4-Bump micro SMD) using National’s micro SMD pack-

age technology. The output voltage may be set at any level

greater than 2.5V (V

REF

) up to 36V merely by selecting two

external resistors that act as a voltage divided network. Due

to the sharp turn-on characteristics this device is an excel-

lent replacement for many zener diode applications.

Features

nAverage temperature coefficient 50 ppm/˚C

nTemperature compensated for operation over the full

temperature range

nProgrammable output voltage

nFast turn-on response

nLow output noise

nLM431 in micro SMD package

nSee AN-1112 for micro SMD considerations

Connection Diagrams

TO-92: Plastic Package

01005501

Top View

SO-8: 8-Pin Surface Mount

01005502

Top view

SOT-23: 3-Lead Small Outline

01005528

Top View

4-Bump micro SMD

01005554

Top View

(bump side down)

Note: *NC = Not internally connected. Must be electrically isolated from the rest of the circuit for the microSMD package.

March 2005

LM431 Adjustable Precision Zener Shunt Regulator

Ordering Information

Package Typical Accuracy Order Number/Package

Marking

Temperature

Range

Transport Media NSC

Drawing

0.5% 1% 2%

TO-92 LM431CCZ/

LM431CCZ

LM431BCZ/

LM431BCZ

LM431ACZ/

LM431ACZ 0˚C to +70˚C

Rails Z03A

LM431CIZ/

LM431CIZ

LM431BIZ/

LM431BIZ

LM431AIZ/

LM431AIZ −40˚C to +85˚C

SO-8 LM431CCM/

431CCM

LM431BCM/

431BCM

LM431ACM/

LM431ACM 0˚C to +70˚C

Rails

M08A

LM431CCMX/

431CCM

LM431BCMX/

431BCM

LM431ACMX/

LM431ACM Tape & Reel

LM431CIM/

431CIM

LM431BIM/

431BIM

LM431AIM/

LM431AIM −40˚C to +85˚C

Rails

LM431CIMX/

431CIM

LM431BIMX/

431BIM

LM431AIMX/

LM431AIM Tape &Reel

SOT-23 LM431CCM3/

N1B

LM431BCM3/

N1D

LM431ACM3/

N1F 0˚C to +70˚C

Rails

MF03A

LM431CCM3X/

N1B

LM431BCM3X/

N1D

LM431ACM3X/

N1F Tape & Reel

LM431CIM3

N1A

LM431BIM3

N1C

LM431AIM3

N1E −40˚C to +85˚C

Rails

LM431CIM3X

N1A

LM431BIM3X

N1C

LM431AIM3X

N1E Tape &Reel

micro SMD

––

LM431AIBP

LM431AIBPX

(Note 1) −40˚C to +85˚C

250 Units Tape and

Reel

3k Units Tape and

Reel

BPA04AFB

Note 1: The micro SMD package marking is a 1 digit manufacturing Date Code only

micro SMD Top View Marking Example

01005556

LM431

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Symbol and Functional Diagrams

01005599

01005555

DC Test Circuits

01005506

Test Circuit for Off-State Current

01005504

FIGURE 1. Test Circuit for V

REF

01005505

Note: VZ=V

REF (1 + R1/R2) + IREF•R1

FIGURE 2. Test Circuit for V

REF

LM431

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Absolute Maximum Ratings (Note 2)

If Military/Aerospace specified devices are required,

please contact the National Semiconductor Sales Office/

Distributors for availability and specifications.

Storage Temperature Range −65˚C to +150˚C

Operating Temperature Range

Industrial (LM431xI) −40˚C to +85˚C

Commercial (LM431xC) 0˚C to +70˚C

Soldering Information

Infrared or Convection (20 sec.) 235˚C

Wave Soldering (10 sec.) 260˚C (lead temp.)

Cathode Voltage 37V

Continuous Cathode Current −10 mA to +150

Reference Voltage −0.5V

Reference Input Current 10 mA

Internal Power Dissipation (Notes 3,

TO-92 Package

SO-8 Package

SOT-23 Package

0.78W

0.81W

0.28W

micro SMD Package 0.30W

Operating Conditions

Min Max

Cathode Voltage V

REF

37V

Cathode Current 1.0 mA 100 mA

LM431

Electrical Characteristics

= 25˚C unless otherwise specified

Symbol Parameter Conditions Min Typ Max Units

REF

Reference Voltage V

REF

= 10 mA 2.440 2.495 2.550 V

LM431A (Figure 1 )

REF

= 10 mA 2.470 2.495 2.520 V

LM431B (Figure 1 )

REF

= 10 mA 2.485 2.500 2.510 V

LM431C (Figure 1 )

DEV

Deviation of Reference Input Voltage Over V

REF

= 10 mA, 8.0 17 mV

Temperature (Note 5) T

= Full Range (Figure 1 )

Ratio of the Change in Reference Voltage I

=10mA V

from V

REF

to 10V −1.4 −2.7 mV/V

to the Change in Cathode Voltage (Figure 2 )V

from 10V to 36V −1.0 −2.0

REF

Reference Input Current R

=10kΩ,R

=∞, 2.0 4.0 µA

=10mA(Figure 2 )

∝I

REF

Deviation of Reference Input Current over R

=10kΩ,R

=∞,

Temperature I

= 10 mA, 0.4 1.2 µA

= Full Range (Figure 2 )

Z(MIN)

Minimum Cathode Current for Regulation V

REF

(Figure 1 ) 0.4 1.0 mA

Z(OFF)

Off-State Current V

= 36V, V

REF

=0V(Figure *NO

TARGET FOR fi* )

0.3 1.0 µA

Dynamic Output Impedance (Note 6) V

REF

, LM431A, 0.75 Ω

Frequency=0Hz(Figure 1 )

REF

, LM431B, LM431C 0.50 Ω

Frequency=0Hz(Figure 1 )

Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Electrical specifications do not apply when operating the device

beyond its rated operating conditions.

Note 3: TJ Max = 150˚C.

Note 4: Ratings apply to ambient temperature at 25˚C. Above this temperature, derate the TO-92 at 6.2 mW/˚C, the SO-8 at 6.5 mW/˚C, the SOT-23 at 2.2 mW/˚C

and the micro SMD at 3mW/˚C.

Note 5: Deviation of reference input voltage, VDEV, is defined as the maximum variation of the reference input voltage over the full temperature range.

LM431

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LM431

Electrical Characteristics (Continued)

01005507

The average temperature coefficient of the reference input voltage, ∝VREF, is defined as:

Where:

T2−T

1= full temperature change (0-70˚C).

∝VREF can be positive or negative depending on whether the slope is positive or negative.

Example: VDEV = 8.0 mV, VREF = 2495 mV, T2−T

1= 70˚C, slope is positive.

Note 6: The dynamic output impedance, rZ, is defined as:

When the device is programmed with two external resistors, R1 and R2, (see Figure 2 ), the dynamic output impedance of the overall circuit, rZ, is defined as:

LM431

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Equivalent Circuit

01005503

Typical Performance Characteristics

Input Current vs V

Thermal Information

01005529

01005530

Input Current vs V

Dynamic Impedance vs Frequency

01005531 01005509

LM431

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Typical Performance Characteristics (Continued)

Stability Boundary Conditions

01005511

Note: The areas under the curves represent conditions that may cause the

device to oscillate. For curves B, C, and D, R2 and V+were adjusted to

establish the initial VZand IZconditions with CL=0.V

+and CLwere then

adjusted to determine the ranges of stability.

01005510

Test Circuit for Curve A Above Test Circuit for Curves B, C and D Above

01005512 01005513

Typical Applications

Shunt Regulator

01005514

Single Supply Comparator with

Temperature Compensated Threshold

01005515

LM431

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Typical Applications (Continued)

Series Regulator

01005516

Output Control of a Three

Terminal Fixed Regulator

01005517

Higher Current Shunt Regulator

01005518

Crow Bar

01005519

LM431

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Typical Applications (Continued)

Over Voltage/Under Voltage

Protection Circuit

01005520

Voltage Monitor

01005521

LM431

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Typical Applications (Continued)

Delay Timer

01005522

Current Limiter or Current Source

01005523

Constant Current Sink

01005524

Application Info

1.0 Mounting

To ensure that the geometry of the micro SMD package

maintains good physical contact with the printed circuit

board, pin A1 (NC) must be soldered to the pcb. Please see

AN-1112 for more detailed information regarding board

mounting techniques for the micro SMD package.

2.0 LM431 micro SMD Light Sensitivity

When the LM431 micro SMD package is exposed to bright

sunlight, normal office fluorescent light, and other LED’s and

lasers, it operates within the guaranteed limits specified in

the electrical characteristics table.

LM431

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Physical Dimensions inches (millimeters) unless otherwise noted

8-Pin SOIC

NS Package Number M08A

SOT-23 Molded Small Outline Transistor Package (M3)

NS Package Number MF03A

LM431

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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)

NS Package Number Z03A

LM431

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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)

NOTES: UNLESS OTHERWISE SPECIFIED

1. EPOXY COATING

2. 63Sn/37Pb EUTECTIC BUMP

3. RECOMMEND NON-SOLDER MASK DEFINED LANDING PAD.

4. PIN A1 IS ESTABLISHED BY LOWER LEFT CORNER WITH RESPECT TO TEXT ORIENTATION. REMAINING PINS ARE NUMBERED.

5. XXX IN DRAWING NUMBER REPRESENTS PACKAGE SIZE VARIATION WHERE X1 IS PACKAGE WIDTH, X2 IS PACKAGE LENGTH AND X3 IS

PACKAGE HEIGHT.

6. REFERENCE JEDEC REGISTRATION MO-211, VARIATION BA.

4-Bump micro SMD

X1 = 0.777 X2 = 0.904 X3 = 0.850

NS Package Number BPA04AFB

National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves

the right at any time without notice to change said circuitry and specifications.

For the most current product information visit us at www.national.com.

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LM431 Adjustable Precision Zener Shunt Regulator