"Isolated Gate Driver" vs "Digital Isolator"

Hi Shai,

Standard opto-coupler is low cost. But it is usually too slow for high speed digital signals. Also, the current transfer ratio (CTR) is usually nonlinear, making it undesirable if the transmitted analog signal has relatively wide range. Typically opto-couplers are used for transmitting on/off signal and in analog power supplies to transmit compensated feedback signal such that the transmitted signal has a narrow range. If you are placing a digital controller on the primary side, standard opto-coupler is not a good choice because the compensator is in the digital controller and ADC wants to read a linear feedback signal from the secondary side. You may look into ISO122 or other linear opto-couplers (usually high cost) if you want to transmit linear analog signal across the insulation. 

Digital isolators, on the other hand, use high-frequency inductive or capacitive coupling across the insulation. But like any digital device, it has finite resolution. They can be used to transmit PWM signals (controller placed on the secondary side). But if the PWM frequency is very high, the available resolution may be a bottleneck.

Thanks,

Zhiyuan

An Isolated Gate Driver should have a higher sourcing/sinking capability on the output, in order to drive the gate of a transistor faster than a digital isolator/optocoupler could provide.  A digital isolator would be used to drive logic circuitry which would have much lower drive requirements.