Industrial Electronics

Video: Optically isolated load-biased gate driver from Littelfuse eliminates the need for external power supply

07 September 2021

Littelfuse Inc. has announced the first high-voltage optically isolated metal-oxide-semiconductor field-effect transistor (MOSFET) gate driver on the market that requires no external power supply, yet can provide fast load turn-on speeds in the order of tens of microseconds.

The CPC1596 570V optically isolated load-biased gate driver is ideal for use in a wide range of power Source: Littelfuse Inc.Source: Littelfuse Inc.electronics applications including industrial controls, automatic test equipment, HVAC controls, medical devices and the internet of things.

"The CPC1596 570V load-biased opto-gate driver addresses a critical market need," said Steve Andrezyk, senior product marketing manager at Littelfuse. "Universal AC power line applications now have a custom, higher power optically isolated solid-state relay (SSR) solution without the cost of an auxiliary power supply or additional discrete devices to meet fast start-up speed requirements."

The CPC1596, showcased in this video, offers these key benefits:

  • Boosts external MOSFET start-up speed by using load-biasing.
  • Eliminates the need for an opto-gate driver auxiliary power supply.
  • Supports optically isolated SSR-applications for both AC and DC.
  • Enables using higher power MOSFETs.
  • Can be controlled from a logic port.

How it works

The problem: standard photovoltaic (PV) gate drivers simplify SSR-design by eliminating the need for auxiliary power supplies. Due to output currents in the µA-range, they get slower with larger gate charges of external MOSFETs, making it difficult to fulfill demanding fast turn-on application requirements.

The solution: The CPC1596 provides fast turn-on switch speed (typically 40 µs) enabling designers to create a custom, higher power, optically isolated, DC-only or AC/DC SSR with external MOSFET(s). To increase the switching speed, simply utilize the product’s unique load-biasing, on-board circuit. The use of load-biasing eliminates the need for an opto-gate driver auxiliary power supply. An internal regulator circuit regulates the voltage drawn from the load supply (up to 570 V) down to 12.2 V for internal use. An external storage capacitor is added to enable constant voltage control for properly driving the MOSFET.


The CPC1596 is provided in tape and reel format in quantities of 1,000.

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