component

UM3429S

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by Ray

Union Semiconductor DC-DC Converters, SOT-23-6. Datasheet-verified pinout, KiCad symbol/footprint/3D.

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3D Model

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Symbol & Footprint

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Datasheet

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Contents

README

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UM3429S

Union Semiconductor · DC-DC Converters · SOT-23-6

UM3429S from Union Semiconductor, in a SOT-23-6. Pinout and pin descriptions extracted from the manufacturer datasheet by ds2sf; symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin Name Type Function
1 SW passive Switch pin - drain of the internal NMOS switch and source of the internal PMOS synchronous rectifier. Connect the external boost inductor between SW and VIN. Keep PCB traces short and wide.
2 GND power_in Device ground. Provide a short, direct PCB path between GND and the negative electrodes of COUT and CIN.
3 FB input Feedback input. Connect to the center of the external resistor divider from VOUT to GND. Reference is 0.6V (VOUT = 0.6V·(1+R1/R2)). Feedback input current is typ. 1nA (max 50nA).
4 SHDN input Active-low logic shutdown input. In shutdown all functions are disabled (<1µA supply current). VIH ≥ 1V, VIL ≤ 0.35V. Do not leave floating.
5 VOUT power_out Output voltage sense input and drain of the internal synchronous PMOS rectifier. Chip bias is derived from VOUT once running. Keep PCB trace from VOUT to output filter capacitor(s) short and wide. Adjustable 2.5V-5V.
6 VIN power_in Battery input voltage (0.5V-5V operating, 0.85V start-up). Device gets start-up bias from VIN; once VOUT > VIN, bias switches over to VOUT. Absolute max 6.0V.

Key specifications

Parameter Value
Manufacturer Union Semiconductor
Package SOT-23-6
Category PMIC
Pins 6

Ordering variants

Same part, different packaging or reel option.

  • UM3429S

CAD (KiCad official)

  • Symbol: UM3429S
  • Footprint: Package_TO_SOT_SMD:SOT-23-6
  • 3D model: SOT-23-6 (KiCad packages3D, STEP)

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

  • Datasheet: Union Semiconductor datasheet (12 pp, sha256 91ce73756d300839, retrieved 2026-08-17, tier: lcsc)
  • 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