LM4040 Precision Voltage Reference

@@ -0,0 +1,53 @@+# LM4040++**Texas Instruments** · Voltage Reference · SOT-23++The LM4040 is a precision shunt voltage reference that works like a precision Zener: a single series resistor sets its bias current and it clamps to a fixed reverse voltage. It comes in fixed grades from 2.048 V to 10 V (this page shows the 2.5 V, SOT-23 DBZ variant) for ADC references, precision bias, and calibration.++## Pinout++| Pin | Name | Type | Function |+|---|---|---|---|+| 1 | CATHODE | passive | Shunt current/voltage input (cathode, marked '+'). Tie through a bias resistor R_S to V_S; the pin regulates at V_KA (2.048V-10V per grade) with cathode current I_Z in the 45µA-15mA range. Absolute maximum continuous cathode current is 25mA; minimum -10mA. |+| 2 | ANODE | passive | Common pin (anode, marked '-'), normally connected to ground / circuit common. Return path for the shunt current I_Z. |+| 3 | NC | unconnected | No internal connection (marked '*'). Must float or be tied to ANODE. TI recommends connecting to ANODE in high-EMI environments (near transformers or high-frequency switching noise). |++## Key specifications++| Parameter | Value |+|---|---|+| Type | Shunt (2-terminal) voltage reference |+| Output voltage | Fixed grades 2.048 V to 10 V (2.5 V shown) |+| Initial accuracy | 0.1% to 1% depending on grade |+| Reverse current range | 60 uA to 15 mA |+| Temp coefficient | 100 ppm/C max (typical grade) |+| Package | SOT-23 (DBZ), 3-lead |+| Operating temperature | -40 C to 85 C |++## Ordering variants++- `LM4040DBZ`+- `LM4040DBZR`+- `LM4040DBZT`+- `LM4040DCK`+- `LM4040DCKR`+- `LM4040DCKT`+- `LM4040LP`+- `LM4040LPR`+- `LM4040LPM`++## CAD (KiCad official)++- Symbol: `lm4040.kicad_sym`+- Footprint: `lm4040.kicad_mod`+- 3D model: SOT-23 body from KiCad `Package_TO_SOT_SMD/SOT-23`.++## Provenance++Data extracted from the manufacturer datasheet, not a distributor listing:++- **Datasheet:** [Texas Instruments datasheet](https://www.ti.com/lit/ds/symlink/lm4040.pdf) (62 pp, sha256 `f59930cb71bcc890`, retrieved 2026-08-17, tier: manufacturer)+- **Extractor:** `ds2sf` (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.+- **CAD:** KiCad official libraries (CC-BY-SA 4.0).++[Datasheet PDF](docs/lm4040-datasheet.pdf)

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