Negative rail workhorse in a small footprint
The LM337IMP is a negative adjustable voltage regulator from Texas Instruments, delivering up to 1.5 A output current with an output range from -1.2 V down to -37 V. It is the negative complement to the LM317 positive regulator family, designed for generating clean negative supply rails in industrial and telecom equipment. The SOT-223-4 surface-mount package (TO-261-4) saves board area compared to the TO-220 through-hole version, though the thermal dissipation limit is lower — the 1.5 A rating assumes adequate copper area on the PCB for heat sinking.
NRND — plan for a last-time buy or alternate
This means Texas Instruments will continue to support existing production for a defined window, but the part is on a path toward end-of-life. For new designs, a pin-compatible alternate within the LM337 family should be evaluated.
The PSRR is specified at 60 dB at 120 Hz — this is the ripple rejection from the input to the output at the full-wave rectifier fundamental frequency. For a -5 V rail powering an op-amp or ADC reference, 60 dB means the 120 Hz ripple on the unregulated input is attenuated by a factor of 1000, keeping the output clean enough for most analog circuits. The built-in over-temperature and short-circuit protection prevent damage under fault conditions, though the thermal shutdown threshold is set to protect the die, not the load — a sustained short at 1.5 A will cycle the part on and off.
Temperature range and package — industrial deployment
For 1.5 A continuous output with a high input-to-output differential, a minimum of 1 square inch of 2-oz copper on the top layer is recommended to keep the junction below 125°C.