ESDAULC45-1BF4 from STMicroelectronics, in a 0201. 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	I/O_1	passive	Bidirectional ESD protection terminal 1. Identified on the package by the pin-1 bar marking (see Figure 20). Connect to the protected data line or to ground; either terminal may be tied to line or ground since the TVS is bidirectional (VBR = 5.8 V min, VRM = 3 V, CLINE = 1.5 pF typ.).
2	I/O_2	passive	Bidirectional ESD protection terminal 2. Opposite end of the TVS from pin 1. Connect to the protected data line or to ground; either terminal may be tied to line or ground since the TVS is bidirectional (VBR = 5.8 V min, VRM = 3 V, CLINE = 1.5 pF typ.).

Key specifications

Parameter	Value
Manufacturer	STMicroelectronics
Package	0201
Category	Circuit Protection
Pins	2

Ordering variants

Same part, different packaging or reel option.

ESDAULC5-1BF4

CAD (KiCad official)

Symbol: ESDAULC45-1BF4
Footprint: Resistor_SMD:R_0201_0603Metric
3D model: 0201 (KiCad packages3D, STEP)

Provenance

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

Datasheet: STMicroelectronics datasheet (None pp, sha256 b9811d5275f131b1, 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