500 mA adjustable regulator in SOT-223-4 — what the PSRR number tells you
The LM317MQDCYR is a positive adjustable voltage regulator from the LM317 family, delivering up to 500 mA output current from a 1.25 V to 37 V adjustable output range. The PSRR of 80 dB to 65 dB at 120 Hz attenuates ripple from a full-wave rectified mains supply — critical when the regulator feeds noise-sensitive analog loads like an ADC reference or an op-amp rail.
Industrial temperature grade and protection
On-chip protection includes over-current limiting, thermal shutdown, and short-circuit current foldback — the regulator survives a sustained output short without external crowbar circuitry.
Housed in a TO-261-4 (SOT-223-4) surface-mount package, the LM317MQDCYR has a 0.50 mm pitch between the three signal leads and the large tab. A 2-layer board with a 1-inch-square copper pour on the tab gives adequate derating for 500 mA at 85°C ambient; thinner copper or smaller pads will force a lower current ceiling.