8.1 Application Information

The LM337-N-MIL is a versatile, high performance, negative output linear regulator with high accuracy and a wide temperature range. An output capacitor can be added to further improve transient response, and the ADJ pin can be bypassed to achieve very high ripple-rejection ratios. The functionality of the device can be utilized in many different applications that require negative voltage supplies, such as bipolar amplifiers, operational amplifiers, and constant current regulators.

8.2 Typical Applications

8.2.1 Adjustable Negative Voltage Regulator

The LM337-N-MIL can be used as a simple, negative output regulator to enable a variety of output voltages needed for demanding applications. By using an adjustable R2 resistor, a variety of negative output voltages can be made possible as shown in Figure 14.

Full output current not available at high input-output voltages
†C1 = 1-μF solid tantalum or 10-μF aluminum electrolytic required for stability
*C2 = 1-μF solid tantalum is required only if regulator is more than 4 inches from power-supply filter capacitor
Output capacitors in the range of 1 μF to 1000 μF of aluminum or tantalum electrolytic are commonly used to provide improved output impedance and rejection of transients

Figure 14. Adjustable Negative Voltage Regulator

Equation 2.

8.2.1.1 Design Requirements

The device component count is very minimal, employing two resistors as part of a voltage divider circuit and an output capacitor for load regulation. An input capacitor is needed if the device is more than 4 inches from the filter capacitors.

8.2.1.2 Detailed Design Procedure

The output voltage is set based on the selection of the two resistors, R1 and R2, as shown in Figure 14.

8.2.1.3 Application Curve

As shown in Figure 15, the maximum output current capability is limited by the input-output voltage differential, package type, and junction temperature.

Figure 15. Current Limit

8.2.2 Adjustable Lab Voltage Regulator

The LM337-N-MIL can be combined with a positive regulator such as the LM317-N to provide both a positive and negative voltage rail. This can be useful in applications that use bi-directional amplifiers and dual-supply operational amplifiers.

Full output current not available at high input-output voltages
*The 10 μF capacitors are optional to improve ripple rejection

8.2.3 −5.2-V Regulator with Electronic Shutdown

The LM337-N-MIL can be used with a PNP transistor to provide shutdown control from a TTL control signal. The PNP can short or open the ADJ pin to GND. When ADJ is shorted to GND by the PNP, the output is −1.3 V. When ADJ is disconnected from GND by the PNP, then the LM337-N-MIL outputs the programmed output of −5.2 V.

Minimum output ≃ −1.3 V when control input is low

8.2.4 High Stability −10-V Regulator

Using a high stability shunt voltage reference in the feedback path, such as the LM329, provides damping necessary for a stable, low noise output.