Welcome to the introduction to the Gate Driver Optocouplers. In the course, we will be introducing the Avago’s Gate Driver Optocouplers and the typical application.

Three Phase Induction Motor with Optocoupler Gate Drivers
Figure shown is a typical three phase induction motor. The six hex-bridge IGBT can be driven with a transformer gate drive, a discrete gate current amplifier drive, an integrated high voltage HVIC gate drive, or an optocoupler gate drive.

Typical IGBT Gate Charge Curve
This is a Typical IGBT Gate Charge Curve. Where Qg is the total gate charge that can be picked readily from the IGBT data sheets, as depicted in the gate voltage vs. gate charge shown in Figure above. From the IGBT data sheets, we know that the turn-ON time, td(on) of the IGBT can be calculated using the equation as shown.

Typical Phototransistor Optocoupler
This is a typical Phototransistor Optocoupler block diagram and Electrical Specifications. From the specifications, we know that a typical phototransistor optocoupler can only output current of milliampere level. The output current can’t drive the IGBT.

ACPL-332J
Here are ACPL-332J block diagram and specification. The ACPL-332J which intelligent gate driver can output 2.5 A current. The output current can drive the IGBT easily.

HCPL-316J
Figure above is the HCPL-316J block diagram and key features. HCPL-316J,the Avago’s 2.5 Amp Gate Drive Optocoupler, has Integrated Desaturation (VCE) Detection and Fault Status Feedback ,which makes IGBT VCE fault protection compact, affordable, and easy-to-implement while satisfying worldwide safety and regulatory requirements. So, HCPL-316J can be used in lots of application easily.

Example
The figure shows a concept for an external blanking circuit. This method uses one additional external resistor, RB, connected from the output to the DESAT pin 14 of the HCPL-316J gate driver. This allows an additional blanking capacitor charging current component from the output of the gate driver optocoupler through RB and this adds to the internal current source of the gate driver optocoupler. This higher external blanking capacitor charging current allows a designer greater flexibility in choosing both an appropriate value of the blanking capacitor, CB, and an appropriate current through the choice of the external resistor RB. By adjusting the capacitance of the blanking capacitor CB and the additional external blanking current through RB, a designer can set a specific precise blanking time.

Additional Resource
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