Current-Based Synchronous Rectifier Topology for Consumer Devices

Semtech Corporation announced the availability of its new synchronous rectifier controller (SR controller). Semtech's SR controller features programmable gate drive voltages used to improve inventory management by allowing customers to utilize a single part for various devices including laptops, cell phones and gaming consoles.

The new SR controller, TS4305, is designed to enhance efficiency in ac-dc adapters and can be used in conjunction with MOSFETs to reduce losses in traditional Schottky rectification diodes, resulting in a smaller and lower cost solution.

Semtech's SR controller is based on a new innovative design that senses the current crossing the MOSFET and offers external adjustable turn-on and turn-off thresholds. While many solutions use a voltage detection approach, Semtech's use of current sensing offers many advantages. When used in ac-dc adapters, the SR Controller enables simpler external circuitry and offers precise turn-on and turn-off timing.

The technology also includes the unique ability to parallel with Schottky diode which is more efficient during light-load operations. All of these advantages results in solutions with higher efficiency and higher power density.

"Semtech's new SR controller is differentiated in the market in three key feature areas: current sensing, adjustable thresholds and programmable gate drive voltages," said Francois Ricodeau, Product Line Manager for Semtech's Power and High-Reliability Products Group. "As a result of these features, customers can now meet the latest regulatory standards on efficiency and power density at a lower cost."

"Consumer market demands are changing and productivity has become a key focus," said Antony Brinlee, Principle Technical Staff of NeoSen Energy. "The new SR controller has accurate current sensing and its adjustability enables users to design power supplies with not only high efficiency, but also with easy to manage bill-of-materials."

Key Features of the Low-side Synchronous Rectifier Controller

  • Accurate current sensing enables higher efficiency
  • Programmable gate drive voltages (5V or 10V) in-line program by customer
  • Minimum ON and OFF time to minimize GATE turn-on oscillation
  • Rectifier turn on/off thresholds set with external resistors
  • Wide supply range 4.5V to 24V
  • 2A sink, 1A source gate drive
  • Available in 2mm x 2mm DFN-8 & 4mm x 5mm or SOIC-8 packages
  • Product is lead-free, halogen free, RoHS / WEEE

The SR controller (TS4305) is available immediately in production quantities and is priced at $0.17 each in 1,000-piece lots.

Semtech Corp.
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