1 Features

1• Adjustable Output Down to 1.2 V

• Ensured 100-mA Output Current

• Line Regulation Typically 0.01%/V

• Load Regulation Typically 0.1%

• Current Limit Constant With Temperature

• Eliminates the Need to Stock Many Voltages

• Standard 3-Pin Transistor Package

• 80-dB Ripple Rejection

• Output is Short Circuit Protected

2 Applications

• Industrial Power Supplies

• Factory Automation Systems

• Building Automation Systems

• PLC Systems

• Instrumentation

• IGBT Drive Negative Gate Supplies

• Networking

• Set-Top Boxes

3 Description

The LM337L is an adjustable 3-pin negative voltage

regulator capable of supplying 100 mA over a –1.2-V

to –37-V output range. The LM337L is easy to use

and requires only two external resistors to set the

output voltage. Both line and load regulation are

better than standard fixed regulators. The LM337L is

packaged in a standard, easy-to-use TO-92 transistor

package.

In addition to higher performance than fixed

regulators, the LM337L offers full overload protection.

Included on the chip are current limit, thermal

overload protection, and safe area protection. All

overload protection circuitry remains fully functional

even if the adjustment pin is disconnected.

Normally, only a single 1-μF solid tantalum output

capacitor is required unless the device is situated

more than 6 inches from the input filter capacitors, in

which case an input bypass is required. A larger

output capacitor can be added to improve transient

response. The adjustment pin can be bypassed to

achieve very high ripple rejection ratios, which are

difficult to achieve with standard 3-pin regulators.

Besides replacing fixed regulators, the LM337L is

useful in a wide variety of other applications. Because

the regulator is floating and monitors only the inputto-

output differential voltage, supplies of several

hundred volts can be regulated as long as the

maximum input-to-output differential is not exceeded.

The LM337L makes a simple adjustable switching

regulator, a programmable output regulator, or by

connecting a fixed resistor between the adjustment

and output, the LM337L can be used as a precision

current regulator. Supplies with electronic shutdown

can be achieved by clamping the adjustment pin to

ground, which programs the output to 1.2 V, where

most loads draw little current.

The LM337L is available in a standard TO-92

transistor package and a standard SO-8 surface

mount package. The LM337L is rated for operation

over a –25°C to 125°C range.

For applications requiring output current in excess of

0.5 A and 1.5 A, The LM137 series may be suitable.

For the positive complement, the LM117 and LM317L

series are options.