TX4120x from XDS, 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	FB	input	Feedback input for the internal error amplifier. An external resistor divider from VOUT to FB sets the output voltage per VOUT = VREF(R1+R2)/R2 with VREF = 0.9 V. Output over-voltage threshold is 1.1VFB.
2	GND	power_in	Device ground return for the internal power stage, control logic, and reference.
3	VDD	power_in	Main input supply, 4.5 V to 36 V absolute max (VIN limited to 27 V when EN switching is used). Bypass close to the pin with a low-ESR ceramic capacitor (X5R/X7R recommended).
4	SW	output	Switching node connecting the internal high-side and low-side MOSFETs. Connect to the external buck inductor and the low-side of the BST bootstrap capacitor. Absolute rating: -0.3 V to VIN+0.3 V.
5	BST	passive	Bootstrap supply for the high-side gate driver. Connect a 100 nF ceramic capacitor between BST and SW; capacitor is refreshed from an internal LDO and typically holds ~5.3 V above SW.
6	CS/LED/EN	bidirectional	Function of pin 6 depends on the factory option: TX4120C = CS (current-limit setting resistor to GND for adjustable current mode), TX4120D = LED (LED status indicator, open-drain to LED cathode), TX4120E = EN (active-high enable input with internal pull-up; leave open to enable). Absolute max on this pin is 6 V.

Key specifications

Parameter	Value
Manufacturer	XDS
Package	SOT-23-6
Category	PMIC
Pins	6

Ordering variants

Same part, different packaging or reel option.

TX4120C
TX4120D
TX4120E

CAD (KiCad official)

Symbol: TX4120x
Footprint: Package_TO_SOT_SMD:SOT-23-6
3D model: SOT-23-6 (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`tx4120x.step`	97 KB	You want the bare part, or you mark your own boards.
`tx4120x-etched.step`	1.3 MB	You want the part with `TX4120x` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 333 faces against 117 in the bare model. It survives export, section views, and rendering in any CAD tool, and it drops straight into KiCad or Fusion with no extra setup.

Provenance

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

Datasheet: XDS datasheet (10 pp, sha256 041da529f91f7840, retrieved 2026-08-17, tier: lcsc)
Datasheet language: Chinese. Pin names, descriptions, and specs on this page were extracted and translated to English by ds2sf; the linked PDF is the manufacturer original.
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