NIKO L431VB, L431NB, L431M5B, L431M3B Datasheet

1

2.5V Low-Voltage Adjustable
Precision Shunt Regulator

NIKO-SEM

L431

JAN-08-Y02

GENERAL DESCRIPTION

The L431 is a three-terminal adjustable shunt
regulator utilizing an accurate 2.5V band-gap
reference. The output voltage can be set to any
value between 2.5V (V

REF

) to 29V with two
external resistors as shown in the typical
application circuit. The device exhibit a wide
operating current range of 0.4 to 100 mA with a
typical dynamic impedance of 0.25Ω. The cha-

racteristics of these reference make it exce­llent replacements for zener diodes in many
applications such as digital voltmeters, power
supplies, and op amp circuitry. The 2.5V volt
reference makes it convenient to obtain a
stable reference from 5.0V logic supplies.
The L431 shunt regulator is available in three
voltage tolerances (0.5%, 1.0% and 2%) and
three package options (TO-92, SOT-23-3,
SOT-23-5 and SOIC-8).

FEATURES

z Internal amplifier with 70 mA capability
z Programmable output voltage to 29V
z 0.25Ωtypical output impedance

z Pin to pin compatible with TL431, LM431

, SC431 & AS431

z Trimmed band-gap design 0.5%, 1.0%

and 2% with three package options

z Low cost solution

APPLICATIONS

z Linear regulator controller
z Precision voltage reference
z Switching power supplies
z Battery operating equipment
z Instrumentation
z PCs, Computer disk drives

SYMBOL & BLOCK DIAGRAM

Anode (A)

Cathod

Reference

-

+

Cathode (K)

Anode (A)

Reference (R)

2.5 Vref

FUNCTIONAL BLOCK DIAGRAM

SYMBOL

(R) (K)

2

2.5V Low-Voltage Adjustable
Precision Shunt Regulator

NIKO-SEM

L431

JAN-08-Y02

ABSOLUTE MAXIMUM RATINGS

PARAMETER VALUE

Cathode-Anode Reverse Breakdown Voltage - VKA 30V
Anode-Cathode Forward Current - IAK 70 mA
Reference Input Current - I

REF

10 mA

Storage Temperature Range - T

STG

-65 to +150 °C
Junction Temperature - TJ 150 °C
Lead Temperature (Soldering, 10 Seconds) - TL 300 °C
Continuous Power at 25 °C - P

D

TO-92
SOIC-8
SOT-23

700 mW
650 mW
200 mW

RECOMMENDED CONDITIONS TYPICAL THERMAL RESISTANCES

Parameter Rating Package

θJA θJC

Typ. Derating

Cathode Voltage (VKA) V

REF

to 29V TO-92 160 °C/W 80 °C/W 6.3 mW/°C

Cathode Current (IK) 10 mA SOIC-8 175 °C/W 45 °C/W 5.7 mW/°C

SOT-23 575 °C/W 150 °C/W 1.7 mW/°C

ELECTRICAL SPECIFICATIONS

(Ambient temperature must be derated base on power dissipation and package thermal characteristics. The conditions are: VKA = V

REF

and

I

K

= 10 mA unless otherwise stated)

PARAMETER TEST CONDITIONS MIN TYP MAX

UNITS

TEST

CIRCUIT

TA = 25 °C, L431 (0.5%) 2.482 2.495 2.507
TA = 25 °C, L431 (1%) 2.470 2.495 2.520

Reference Voltage

TA = 25 °C, L431 (2%) 2.445 2.495 2.550

V

1

∆V

REF

with Temp. 0.07 0.2

mV/°C

1

V

REF

to 10V -2.7 -1.0 Ration of Change in V

REF

to

Cathode Voltage

10V to 30V -2.0 -0.4 0.3

mV/V

2

Reference Input Current 0.7 4

µA

2

I

REF

Temp. Deviation Over Temp. 0.4 1.2

µA

2

Min. IK for Regulation 0.4 1

mA

1

Off State Leakage V

REF

= 0V, VKA = 30V 0.04 250

nA

3

Dynamic Output Impedance

f ≤ 1KHz, IK = 1 to 70 mA

0.25 0.5

Ω

1

3

2.5V Low-Voltage Adjustable
Precision Shunt Regulator

NIKO-SEM

L431

JAN-08-Y02

TEST CIRCUITS

IN

VV

KA

K

I

REF

I

V

REF

R1

R2

- TEST CIRCUIT 2 ­>(V

KA

V

REF

)

REF

I

)V

KA

V

=

- TEST CIRCUIT 1 -

KA

V

REF

(V

IN

- TEST CIRCUIT 3 -

KA

VV

IN

K (OFF)

I

(OFF STATE CURRENT)

I

K

The areas under the curves represent conditions that may

cause the device to oscillate. For curves B, C and D, R

1 and

V

BATT were adjusted to establish the initial VKA and IKA

conditions with C

L = 0. VBATT and CL then were adjusted

to determine the ranges of stability.

Stability Boundary Condition For Shunt Regulation

VS. Cathode Current and Load Capacitance

1023 4 56

CL

Ik

150

12

L431

2 3

1

Test Circuit for Vka = Vref

150

L431

2 3

1

10K

R2

Test Circuit for Vka > Vref

Ik

R1

CLVBATT

12

4

2.5V Low-Voltage Adjustable
Precision Shunt Regulator

NIKO-SEM

L431

JAN-08-Y02

Small-Signal Gain and Phase Shift

VS. Frequency

VS. Cathode Voltage

Cathode Current

Cathode Current

VS. Cathode Voltage

VS. Junction Temperature

r

z

(

Ω

)

Reference Impedance

VS. Junction Temperature

Ratio of Delta Reference Voltage to Delta Cathode Voltage

Δ

V

r

e

f

/

Δ

V

z

(

-

m

V

/

V

)

ΔVz = 3V to 30V

8.25K

OUT

Ik

GND

15K

12

L431

2 3

1

10uF

232

12

Test Circuit for Small Signal Gain and Phas

e