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Half-bridge drivers to drive high-side switch in half-bridge configuration – KBA236411

Half-bridge drivers to drive high-side switch in half-bridge configuration – KBA236411

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Community Translation: ハーフブリッジ構成でハイサイド スイッチを駆動するハーフブリッジ ドライバ – KBA236411

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Use the following to drive a high-side switch in a half-bridge configuration:

  1. Optocoupler
  2. Digital isolator

Using optocoupler

It provides galvanic isolation between two sides functionally and inherently shifts the high side in a single package or in two separate packages. Though conventional optocouplers have many disadvantages (as listed below), the introduction of a CMOS-based optocoupler raises the performance and reliability of isolated drivers. The CMOS-based optocoupler reduces the delay time significantly.

Following are the disadvantages of a conventional optocoupler-based isolated driver:

  1. More delay time
  2. Because the optocoupler has a separate package, there might be a channel mismatch issue that may lead to an increase in dead time.
    Infineon_Team_0-1666171359590.png
    Figure 1 Optocoupler-based isolated gate driver IC

 


Using digital isolator

A digital isolator with an isolated driver IC can also be used to drive the half-bridge configuration. Because the digital isolator provides reinforced isolation, the isolated driver IC used has only functional isolation, such as a dual-channel isolated IC. This configuration is generally used in DC-DC power supplies for telecom applications and serves as a suitable substitute for the optocoupler driver IC.

Advantages:

  1. Despite adding a component (digital isolator), it gives high flexibility in placing the components.
  2. Because the reinforced isolation is provided by the digital isolator, the driver IC can be kept close to the switch, which reduces the parasites in the gate path leading to low oscillations in gate voltage.
    Infineon_Team_2-1666171445511.png

     

    Figure 2 Half-bridge solution with digital isolator and dual channel isolated driver IC
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