iW671 synchronous rectifier - replacing Schottky diodes, enabling higher power, smaller form factor smartphone and tablet power adapters
LONDON — (BUSINESS WIRE) — September 22, 2014 — Dialog Semiconductor plc (FWB: DLG), a provider of highly integrated power management, AC/DC, solid state lighting and Bluetooth(R) Smart wireless technology, today launched its iW671 synchronous rectifier designed to enable small, higher power adapters for mobile devices. The iW671 replaces the secondary-side Schottky diode used in conventional power supplies with a more efficient MOSFET and works with Dialog's iW1786 or iW1787 primary-side controllers to deliver efficiency greater than 88%. This enables the higher power density needed for more powerful, small form-factor adapters without exceeding thermal limits.
Conventional power supplies use Schottky diodes to rectify the output voltage (change the AC voltage to a DC voltage). When replacing the Schottky diode with a synchronous rectifier, the voltage dropped across the switching MOSFET is less than the forward voltage of the Schottky diode, thereby reducing power loss. However, conventional synchronous rectifiers still require a Schottky diode to be used in parallel as they need to turn off when approaching the zero crossing to eliminate the risk of shoot-through, which can overheat and potentially destroy the power supply. The iW671 uses Dialog's proprietary digital control technology to eliminate the need for the parallel Schottky diode. Synchronous rectification also leads to an efficiency improvement of approximately 4% at 5V, resulting in the high >88% full-load efficiency for higher power operation in a small form-factor without overheating the power supply.
The iW671 is designed to work for 15W or 50W output power, ultra-low no-load standby power consumption of < 15mW (iW1786) and < 30mW (iW1787) and high efficiency, enabling chargers and adapters to meet stringent global energy standards including the final 2014 U.S. DOE(1) and European CoC version 5, tier 2(2) regulations.
Power supplies for electronic products continue to consume power when plugged in but not in use. To achieve low standby power, these power supplies typically enter a low standby operating mode. However, when a load is applied, they need to "wake up" quickly to keep the output voltage from dropping too low. Dynamic load response (DLR) is determined by the speed at which the system wakes up and responds to changes in the power load. Typical adapter and charger design approaches achieve low standby power and high efficiency at the expense of slow wake up (i.e. slow DLR performance). The iW671 enables ultra-fast DLR for quicker recovery from low-power standby mode by integrating an adaptive voltage position monitor that detects the flyback converter output voltage undershoot.
"With global energy regulations for power consumption becoming more and more stringent, power supplies are being pushed to their cost, performance and size limits," said Davin Lee, Senior Vice President and General Manager of the Power Conversion Business Group at Dialog Semiconductor. "Dialog's innovative iW671 synchronous rectifier and controller solutions will now provide designers with the ultimate combination of higher efficiency, faster standby recovery performance and a reduced BOM for a new generation of low cost adapters and chargers."
- iW1786+iW671: up to 15W output power, < 15mW no-load standby power consumption
- iW1787+iW671: up to 50W output power, < 30mW no-load standby power consumption
- Eliminates parallel Schottky diode
- Higher efficiency >88% (full load)
- Fast dynamic load response
- Complies with US DOE(1) and EU CoC V5, Tier 2(2) requirements for external power supply efficiency
Product summaries are available: iW671 Product Summary, iW1786 Product Summary, iW1787 Product Summary
- ENDS -
(1) US Department of Energy (DOE), Energy Conservation Program: Energy Conservation Standards for External Power Supplies, Final Rule, 10 CFR Part 430, ID: EERE-2008-BT-STD-0005-0219, February 10, 2014,
(2) European Commission, Directorate-General Joint Research Centre, Institute for Energy and Transport, Renewable Energy Unit, "External Power Supplies Code of Conduct - Version 5," October 29, 2013,
About Dialog Semiconductor Dialog Semiconductor creates highly integrated, mixed-signal integrated circuits (ICs), optimised for personal portable, short-range wireless connectivity, LED solid state lighting and automotive applications. The company provides flexible and dynamic support, world-class innovation and the assurance of dealing with an established business partner.
With its focus and expertise in energy-efficient system power management
and a technology portfolio that also includes audio, short-range
wireless, AC/DC power conversion and multi-touch, Dialog brings decades
of experience to the rapid development of ICs for personal portable and
digital consumer applications, including smartphones, tablets,
Ultrabooks(TM) and emerging wearable type devices. Dialog's power
management ICs increase the performance of portable devices by extending
battery lifetime, enabling faster charging and enhancing the consumer's
experience. With world-class manufacturing partners, Dialog operates a
fabless business model.