Electronic Devices & Circuits · Lecture 12

The Peak Inverse Voltage and Surge Current in Diodes

Diodes & Basic Applications

Dr. Mithun Mondal BITS Pilani, Hyderabad Campus

  • Peak Inverse Voltage (PIV): Maximum voltage across a non-conducting diode

  • PIV Requirement: Must be less than diode’s breakdown voltage

  • Worst Case: Capacitor-input filter

  • Symbols for Maximum Reverse Voltage: PIV, PRV, \(V_B\), \(V_{BR}\), \(V_{R}\), \(V_{RRM}\), \(V_{R(max)}\)

  • Half-Wave Rectifier with Capacitor-Input Filter

    • Critical part: Determines reverse voltage

    • Worst case: Peak secondary voltage negative, capacitor fully charged

    • Peak Inverse Voltage (PIV):

    • Example: Peak secondary voltage = 15 V

    • Diode must have breakdown voltage greater than PIV

    • \[\mathrm{PIV} = 2 \times 15\,\text{V} = 30\,\text{V}\]
    \[\mathrm{PIV} = 2V_p\]
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  • Full-Wave Rectifier with Capacitor-Input Filter

    • Critical part: Determines peak inverse voltage

    • Secondary voltage at negative peak

    • Lower diode: short (closed switch), upper diode: open

    • Peak Inverse Voltage (PIV):

    • \[\mathrm{PIV} = V_p\]
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  • Bridge Rectifier with Capacitor-Input Filter

    • Critical part: Determines peak inverse voltage

    • Upper diode: short (closed switch), lower diode: open

    • Peak Inverse Voltage (PIV):

    • Advantage: Lowest PIV for a given load voltage

    • Compared to full-wave rectifier: Requires half the secondary voltage for same load voltage

    • \[\mathrm{PIV} = V_p\]
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SECTION 01

Surge Resistor

SECTION 02

Problem on Peak inverse voltage

What is the peak inverse voltage if the turns ratio is \(8: 1\) ? The diode has a breakdown voltage of 50 V . Is it safe to use the diode in this circuit?

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