1.235 V shunt reference in a hand-solderable SOT-23-3
The Texas Instruments LM385M3-1.2/NOPB is a micropower shunt voltage reference that delivers a fixed 1.235 V output with a 20 mA output current capability and a minimum cathode current of just 10 µA. Packaged in a SOT-23-3, it's a part you can hand-solder with a fine-tip iron — no hot-air station required. The shunt topology means it behaves like a two-terminal Zener, so you just add a series resistor from your supply rail and it regulates. Great for a weekend project where you need a stable bias for an op-amp or an ADC reference on a breadboard.
The output tolerance is specified at -2.43%, +2.02% — that's a spread of roughly 1.203 V to 1.260 V on the 1.235 V nominal. For a general-purpose reference in a 5 V system, that's fine; for a precision 12-bit ADC, you'll want to measure the actual voltage at your operating current and temperature. The temperature coefficient of 150 ppm/°C means the output drifts about 0.185 mV per degree C, so keep it away from hot components on the board if you need stability.
Active production — no LTB worry
No official replacement or second-source alternate is listed, but the LM385 family is widely second-sourced — if you need a pin-compatible alternative, the generic LM385M3-1.2 from other vendors is a drop-in, though always verify the tolerance and temp range against your requirement.
The SOT-23-3 footprint (TO-236-3 / SC-59 compatible) is a standard three-lead layout — the cathode is the output, the anode goes to ground, and the reference pin is the adjust (though this is the fixed version, so no external divider needed). The shunt architecture means the total current drawn from the supply is the load current plus the cathode current (minimum 10 µA), so it's efficient for battery-powered gear where every microamp counts.