Ac-dc chip for industrial auxiliary PSUs up to 21W

Called InnoSwitch3-TN, “our new devices support the high output current needed in smart-connected appliances at efficiencies of up to 90%, compared to traditional approaches such as buck regulators,” said Power Integrations marketing manager Silvestro Fimiani. “InnoSwitch3-TN ICs incorporate all feedback components while supporting isolated, non-isolated, single and multi-output designs for auxiliary power supply.”

No-load consumption can be as low as 5mW.

Reference design RDK-710 is available for evaluating InnoSwitch3-TN

Inside, isolated feedback is through the company’s safety-rated (every chip is hi-pot tested, it said) inductive FluxLink, which “ensures reliable synchronous rectification and accurate constant voltage and constant current on the output”.

Amongst other elements, the primary side has a high-voltage mosfet and quasi-resonant fly-back controller that can operate in continuous conduction, boundary and discontinuous modes. It uses a combination of variable frequency and variable current control, and has a frequency jittered oscillator.

The secondary controller has multiple blocks including its link interface, constant-voltage and constant-current control circuits, a 4.4V regulator for the secondary bypass pin and a synchronous rectifier mosfet driver.

It can be used in a 5V single-output power supply, with two positive output rails, or with both positive and negative rails, without any external feedback components. The low forward drop of the output synchronous rectifier mosfet aids cross-regulation on multi-output supplies.

Safety features include output over-current and over-temperature protection.

The InnoSwitch3-TN product page is here, and there is a well-presented video, with good information throughout its five minutes.