Negative rail workhorse — 1.5 A adjustable in SOT-223-4
The Texas Instruments LM337IMP/NOPB is a negative adjustable voltage regulator delivering up to 1.5 A output current from a -1.2 V to -37 V output range, in a surface-mount SOT-223-4 package. It is the negative complement to the LM317 family, used wherever a clean negative rail is needed — op-amp bipolar supplies, ADC/DAC reference rails, or local board-level regulation in industrial and automotive environments.
1.5 A output — sizing the load and the thermal budget
Rated for 1.5 A continuous output, this part handles moderate local loads like analog front-end rails or small motor drives. The SOT-223-4 package has a thermal pad on the tab — the board copper area under that pad sets the junction-to-ambient thermal resistance; at 1.5 A with a moderate dropout, a 2 oz copper pour of at least 1 in² is typical to keep junction temperature below the 125°C maximum. Output voltage is adjustable with two external resistors down to -1.2 V reference, and the maximum input voltage is -40 V, giving headroom for -48 V telecom rails or -24 V industrial buses.
60 dB PSRR — ripple rejection for sensitive analog rails
The 60 dB PSRR at 120 Hz is the figure that matters for audio or precision analog designs — it attenuates full-wave rectifier ripple by a factor of 1000. That keeps hum off the negative supply of an op-amp or ADC reference, which directly affects noise floor and THD in the signal path.