Sample-and-hold in a hermetic can
The LF398H/NOPB is a monolithic sample-and-hold amplifier from Texas Instruments, packaged in the TO-99-8 metal can — a hermetic enclosure that suits high-reliability environments where moisture and outgassing are concerns. Through-hole mounting means the PCB must be drilled for the TO-99 footprint; no reflow profile needed, but the assembly step is manual or wave-solder.
What the ratings mean for the signal chain
With a 10 nA input bias current, the hold capacitor droops at roughly 10 nA/C — for a 0.1 µF hold cap the voltage decays about 0.1 mV/ms, setting the acquisition window and the conversion accuracy at the ADC. The 2 mV input offset voltage adds a DC error that can be nulled externally or accounted for in software calibration. The 4.5 mA supply current is drawn from the 10 V to 36 V supply span. This wide range allows operation from standard ±15 V analog rails or a single 24 V industrial supply — the part does not require a negative rail, though the input common-mode range is ground-referenced in single-supply mode. Commercial temperature grade (0°C to 70°C) limits the part to controlled indoor environments. For extended industrial or automotive ambient, the LF398H/NOPB is not rated — a military-temperature variant would be needed.