The LM2940T-9.0 carries a Not Recommended for New Designs (NRND) status. If you are refreshing a legacy board or filling a BOM line for a current product, the part is still orderable — but any new design should target a pin-compatible replacement before the end-of-life notice drops.
1A fixed 9V rail — what the dropout means at load
This is a single-output positive LDO delivering a fixed 9V at up to 1A. The maximum dropout voltage is 1V at full load, so the input rail needs to stay above 10V to maintain regulation. With a 26V absolute maximum input, it handles unregulated supplies from 12V or 24V buses comfortably.
PSRR and protection — analog supply suitability
PSRR is 64dB at 120Hz, which is typical for a 1A LDO of this generation. That is enough rejection for most 9V analog rails feeding op-amps or small signal chains, but if you need better ripple rejection above 1 kHz, a higher-PSRR LDO or a post-filter stage is worth considering. The built-in protection suite — over-current, over-temperature, reverse polarity, and short-circuit — covers the common fault modes in industrial and automotive environments.
Temperature range and package — industrial and automotive ready
The TO-220-3 through-hole package with a metal tab lets you bolt it to a heatsink or chassis — the tab is the output pin, so the heatsink path is electrically live.