Supertex inc.

LR12

Supertex inc.

www.supertex.com

Doc.# DSFP-LR12

C080113

High Input Voltage, Adjustable

3-Terminal Linear Regulator

Features

Applications

General Description

The Supertex LR12 is a high voltage, low output current,

adjustable linear regulator. It has a wide operating input voltage

range of 13.2 - 100V. The output voltage can be adjusted from

1.20 - 88V, provided that the input voltage is at least 12V greater

than the output voltage. The output voltage can be adjusted

by means of two external resistors R

typical application circuits. The LR12 regulates the voltage

difference between VOUT and ADJ pins to a nominal value of

1.20V. The 1.20V is amplified by the external resistor ratio R

1

and R

connected to the ADJ pin. This increases V

voltage of 10µA times R

The LR12 has current limiting and temperature limiting. The

output current limit is 100mA maximum and the minimum

temperature limit is 125°C. An output short circuit current will

therefore be limited to 100mA maximum. When the junction

temperature reaches its temperature limit, the output current

and/or output voltage will decrease to keep the junction

temperature from exceeding its temperature limit. For SMPS

start-up circuit applications, the LR12 turns off when an external

voltage greater than the output voltage of the LR12 is applied

to VOUT of the LR12. To maintain stability, a bypass capacitor

of 100nF or larger and a minimum DC output current of 500µA

are required.

LR12 Typical Application

V

IN

13.2 to 100V

*

* Required for conditions where V

R

1

R

2

C

2

C

1

R

LOAD

V

OUT

1.2 to 88V

LR12

VOUT

ADJ

VIN