Unidirectional TVS Diodes and Selectable Polarity Options
Compare unidirectional transient-voltage-suppression (TVS) diodes for surge-sensitive power and electronic lines. This collection includes fixed P6KE200A, SMBJ200A, SMBJ15A and SMF5.0A packs; selectable P6KE A and 1.5SMC A grades; and compact D6V3H1U2LP-7B and ESD56201D04-2 protection listings. Some menus also contain bidirectional CA variants. The collection heading does not change the polarity of the option you select.
Identify the correct package and choice
- Axial P6KE and 1.5KE: P6KE200A is listed as a 20-piece fixed pack. Another P6KE A menu offers 50 pieces of the selected grade from P6KE6.8A through P6KE220A; this is one model per choice, not a full assortment. A 1.5KE DO-201AD menu offers 10-piece A and CA choices from 6.8 through 36. The shared product title mentions both directions, so check the complete selected suffix.
- SMB and SMA packages: fixed SMBJ200A and SMBJ15A listings are 100-piece packs; separate SMBJ12–SMBJ16 menus offer A and CA options in a nominal 100-piece listing. SMAJ13A and SMAJ13CA are distinct 20-piece choices. Do not assume that a menu labeled “unidirectional bidirectional” sends both types.
- SMC and compact SMD: two 1.5SMC A menus offer 10-piece selections spanning 6.8–68 and 75–540 grade numbers in SMC-type packages. SMF5.0A is a separate 50-piece SOD-123FL listing. D6V3H1U2LP-7B in X1-DFN1006-2 and ESD56201D04-2 in DFN1610-2L are compact ESD-protection listings with distinct footprints and pulse behavior; inspect their exact manufacturer datasheets rather than substituting them for large-case surge suppressors.
Selection checklist
- Determine the protected line's maximum normal voltage. Compare the selected part's reverse standoff voltage (VRWM), breakdown range (VBR) and clamping voltage (VC) at a specified pulse current with the circuit's withstand limit. A number such as 15 or 200 in a part designation is not automatically the clamping voltage.
- Confirm direction from the selected full part number: A commonly denotes unidirectional and CA bidirectional in these TVS families, but manufacturer nomenclature and markings must be verified. A unidirectional part may conduct in the forward direction, making orientation and normal negative excursions important.
- Compare waveform-specific peak pulse current and power, pulse repetition and temperature derating on the manufacturer's datasheet. A seller's “600 W”, “1.5 kW”, “±30 kV” or clamp headline does not by itself establish your system's surge or ESD rating.
- Check mechanical drawing and terminals before placing parts on a board. Axial DO-15/DO-201, SMA, SMB, SMC, SOD-123FL and DFN outlines differ in footprint and thermal paths. Generic imported product-type fields can contradict the exact device name and are not a design specification.
- Confirm selected model and pack quantity. “Color” may encode the electrical grade rather than color; single-model 10-, 20-, 50- or 100-piece packs do not include every option displayed in the title.
Frequently asked questions
Are SMBJ12A and SMBJ12CA both unidirectional?
No. The menu includes both suffixes; A and CA commonly denote different suppression directions. Check the exact selected part's datasheet and polarity marking.
Can I replace P6KE200A with SMBJ200A?
Not by matching the number alone. Axial P6KE and surface-mount SMBJ differ in package, transient performance and thermal constraints; compare their full datasheets under the same pulse conditions.
Does a 1.5SMC title listing many grades deliver the whole range?
No. Its options select one 10-piece grade per order. Review the chosen variant before purchasing.
Is “bipolar” in an SMBJ200A seller title proof of bidirectional protection?
No. That wording conflicts with the A designation commonly used for unidirectional parts. Verify the exact manufacturer designation and marking rather than relying on that phrase.
