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LM4040 Precision Voltage Reference

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by Ray

Precision shunt (2-terminal) voltage reference, fixed output grades from 2.048 V to 10 V.

voltage-referenceshuntprecisionanalogtisot-23
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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

Same part, different packaging or reel option.

  • 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 (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