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Made with KiCad 10.0 · needs KiCad 10.0 or later to open · KiCad file format 20260206

Name	Last commit message	Last updated
docs	Publish 0.1.0 · Ray	14d ago
viewers	sz1smb28cat3g: symbol repaired (D_Zener, cathode pad 1) · Ray	1d ago
package.json	Publish 0.1.0 · Ray	14d ago
page.json	Set visibility: public · Ray	14d ago
README.md	Publish 0.1.0 · Ray	14d ago
sz1smb28cat3g-etched.glb	Publish 0.1.0 · Ray	14d ago
sz1smb28cat3g-etched.step	sz1smb28cat3g: factory component page (tier=lcsc) · Ray	14d ago
sz1smb28cat3g-hero.glb	sz1smb28cat3g: hero GLB from the etched model (keeps the MPN mark) · Ray	14d ago
sz1smb28cat3g-hero.overlay.json	Publish 0.1.0 · Ray	14d ago
sz1smb28cat3g.glb	Publish 0.1.0 · Ray	14d ago
sz1smb28cat3g.kicad_mod	Publish 0.1.0 · Ray	14d ago
sz1smb28cat3g.kicad_sym	sz1smb28cat3g: symbol repaired (D_Zener, cathode pad 1) · Ray	1d ago
sz1smb28cat3g.lbr	sz1smb28cat3g: symbol repaired (D_Zener, cathode pad 1) · Ray	1d ago
sz1smb28cat3g.step	Publish 0.1.0 · Ray	14d ago

SZ1SMB28CAT3G

Littelfuse · TVS · SMB

SZ1SMB28CAT3G from Littelfuse, in a SMB. Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin	Name	Type	Function
1	Cathode	passive	TVS terminal 1 (marked cathode on the SMB outline); bidirectional part, so this terminal is symmetrical with pin 2: VRWM 28 V, VBR 31.1-34.4 V @ 1 mA, VC 45.4 V @ IPP 13.2 A, 600 W peak pulse power (10/1000 µs).
2	Anode	passive	TVS terminal 2 (marked anode on the SMB outline); bidirectional part, so this terminal is symmetrical with pin 1: IR max 5.0 µA @ VRWM 28 V.

Key specifications

Parameter	Value
Manufacturer	Littelfuse
Package	SMB
Category	Circuit Protection
Pins	2

Electrical characteristics

Limits as printed in the datasheet (page.json metadata.characteristics carries them as data).

Parameter	Symbol	Min	Typ	Max	Unit	Conditions	Page
Working Peak Reverse Voltage	VRWM		28		V		4
Maximum Reverse Leakage Current	IR			5	µA	@ VRWM	4
Breakdown Voltage	VBR	31.1	32.74	34.4	V	@ IT = 1.0 mA, TA = 25°C	4
Clamping Voltage	VC			45.4	V	@ IPP = 13.2 A	4
Maximum Reverse Peak Pulse Current	IPP			13.2	A		4
Peak Power Dissipation	PPK			600	W	TL = 25°C, pulse width = 1 ms, 10/1000 µs non-repetitive	1
DC Power Dissipation	PD			3	W	TL = 75°C, measured zero lead length, 1" square copper pad FR-4	1
DC Power Dissipation	PD			0.55	W	TA = 25°C, FR-4 board, Littelfuse minimum recommended footprint	1
Thermal Resistance Junction-to-Lead	RƟJL			25	°C/W		1
Thermal Resistance Junction-to-Ambient	RƟJA			226	°C/W		1
Forward Surge Current	IFSM			100	A	TA = 25°C, 1/2 sine wave, PW = 8.3 ms, unidirectional only	1
Operating and Storage Temperature Range	TJ, Tstg	-65		150	°C		1
Derate Above 75°C			40		mW/°C	Derate above 75°C	1
Derate Above 25°C			4.4		mW/°C	Derate above 25°C	1

Materials and finish

As the datasheet states them (page.json metadata.appearance; the 3D model's colours follow it).

Part	Material	Colour / plating	Datasheet says	Page
contacts		tin	and the terminal finish material is tin(Sn) (IPC/	1

CAD (KiCad official)

Symbol: SZ1SMB28CAT3G
Footprint: Diode_SMD:D_SMB
3D model: SMB (KiCad packages3D, STEP)
3D model files: sz1smb28cat3g-etched.step / sz1smb28cat3g-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); sz1smb28cat3g.step / sz1smb28cat3g.glb are the bare package body.

Provenance

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

Datasheet: Littelfuse datasheet (7 pp, sha256 b867ff8d1ae59140, retrieved 2026-10-22, tier: lcsc)
Extractor: parts-factory 2.0.0 / extract_pins 0.3, primary claude-sonnet-5-5 (text), consensus claude-sonnet-5-5 (agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish.
CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF