What this quad JFET op-amp is and where it lands on the bench
The STMicroelectronics LF347D is a JFET-input quad operational amplifier in a 14-SOIC package. It gives you four independent op-amp channels with a 3 MHz gain-bandwidth product and a 13V/µs slew rate — enough to handle audio-band signals and moderate-speed analog processing without the output rounding off. The JFET inputs keep input bias current at 50 pA, which matters when you're buffering high-impedance sources like photodiodes or piezo sensors. Supply range runs from 7 V to 36 V total, so it fits both single-rail and split-rail designs common in bench instruments, audio mixers, and industrial signal conditioning.
Active production — no LTB scramble
The LF347D carries an Active lifecycle status and is ROHS3 compliant. That means ST is still making it, there's no last-time-buy clock ticking, and you can qualify it into a new BOM without worrying about an imminent EOL notice. For repair stock, that's the difference between ordering a fresh reel and hunting down NOS on the broker market.
SOIC-14 footprint — fits the board without re-spinning
The 14-SOIC (0.154", 3.90 mm width) body is a standard narrow SOIC footprint. The 40 mA per-channel output current is enough to drive a headphone amp or the input of an ADC.