TVS Diode Selection
Select a TVS from the protected circuit maximum operating voltage, downstream withstand voltage, and surge current; check standoff voltage, clamping voltage, peak pulse power, and rated surge-current margin.
Key points
TVS Diode Selection: Select a TVS from the protected circuit maximum operating voltage, downstream withstand voltage, and surge current; check standoff voltage, clamping voltage, peak pulse power, and rated surge-current margin. Formula: Vc = Vbr + Ipp·(Vc_rated − Vbr)/Ipp_rated ｜ Ppp = Vc·Ipp ｜ E ≈ Vc·Ipp·tp. Enter parameters on the DD-CAT IDE online tool page to get results instantly, with a calculation-model diagram that updates with the inputs. TVS standoff voltage Vwm must exceed the maximum circuit voltage (including ripple, tolerance, and temperature rise), otherwise it leaks or heats in normal operation. Clamping voltage must stay below the downstream absolute maximum; a TVS diverts energy but does not replace a fuse or current-limiting resistor.
Inputs
Vc = Vbr + Ipp·(Vc_rated − Vbr)/Ipp_rated ｜ Ppp = Vc·Ipp ｜ E ≈ Vc·Ipp·tpCalculation model (updates with parameters)
| Suggested minimum standoff voltage Vwm | ≥ 13.2 V | 按 1.1×Vop 估算，High temperature漏电大时取 1.2× |
| Vwm margin over operating voltage | 25.0 % | recommend ≥10% |
| Actual clamping voltage Vc @ Ipp | 19.78 V | Vbr 16.7 V + Ipp·Rd |
| Downstream withstand margin | 220 mV（1.1 %） | 留 20% 以上更稳妥 |
| Peak pulse power Ppp | 197.8 W | 按实际浪涌currentCalculate |
| Single-pulse energy E (approx.) | 3.956 mJ | RectangleEquivalent；实际按波形integrator，8/20µs 偏保守 |
| Rated current margin | 2.50 × | recommend ≥1.25×，高可靠场景 ≥2× |
| Selection result | 通过 ✓ | Vwm / 钳bits / current裕量均met |
Engineering notes
- TVS standoff voltage Vwm must exceed the maximum circuit voltage (including ripple, tolerance, and temperature rise), otherwise it leaks or heats in normal operation.
- Clamping voltage must stay below the downstream absolute maximum; a TVS diverts energy but does not replace a fuse or current-limiting resistor.
- Estimate surge current from the test waveform (8/20 µs, 10/1000 µs, etc.) and source impedance; verify against the manufacturer pulse-derating curve.
FAQ
- What is TVS Diode Selection for?
- Select a TVS from the protected circuit maximum operating voltage, downstream withstand voltage, and surge current; check standoff voltage, clamping voltage, peak pulse power, and rated surge-current margin.
- What is the formula for TVS Diode Selection?
- Core formula: Vc = Vbr + Ipp·(Vc_rated − Vbr)/Ipp_rated ｜ Ppp = Vc·Ipp ｜ E ≈ Vc·Ipp·tp. The tool returns results instantly using this formula and the selected parameters.
- What engineering notes should I keep in mind when using TVS Diode Selection?
- TVS standoff voltage Vwm must exceed the maximum circuit voltage (including ripple, tolerance, and temperature rise), otherwise it leaks or heats in normal operation. Clamping voltage must stay below the downstream absolute maximum; a TVS diverts energy but does not replace a fuse or current-limiting resistor. Estimate surge current from the test waveform (8/20 µs, 10/1000 µs, etc.) and source impedance; verify against the manufacturer pulse-derating curve.