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.