Fixed 2.5 V rail for automotive sensor chains
The LM4128CQ1MF2.5/NOPB is a series voltage reference from Texas Instruments, part of the Automotive, AEC-Q100 family. It delivers a fixed 2.5 V output with ±0.5% initial tolerance, which means the reference voltage stays within 12.5 mV of the nominal value across the production spread — tight enough for a 12-bit ADC's Vref pin without extra trimming. The 20 mA output current can bias several sensor front-ends or a small DAC reference input without a buffer.
Temperature stability and noise floor
That is acceptable for a powertrain sensor reference where the ECU compensates the ADC reading in firmware, but marginal for a precision DAC that needs sub-mV stability across temperature. This flicker-noise floor sets the usable resolution for DC-coupled measurements — a 12-bit ADC with a 2.5 V reference has an LSB of 610 µV, so the reference's own noise eats about half the least-significant bit at the low end of the bandwidth. Quiescent supply current is 100 µA typical. That is low enough to leave on continuously in a key-off automotive module without draining the battery, but not as aggressive as a nanopower reference — budget it into the sleep-mode current budget.
Supplied in a 5-pin SOT-23-5 (SC-74A) package, surface-mount only. The footprint is standard — 0.95 mm pitch, 2.9 mm body length — and routes easily on a two-layer board. No exposed thermal pad; the junction-to-ambient thermal resistance is dominated by the copper area on the output pin. The reel quantity is not listed here, but the CT option means you can order a handful for first-article builds without committing to a full reel.
Lifecycle status is Active — Texas Instruments continues to manufacture this part with no announced end-of-life. ROHS3 compliant per the entry.