New LinkSwitch-4 switcher ICs pass US DoE-6 and European CoC efficiency rules

Power Integrations, working in high-voltage integrated circuits for energy-efficient power conversion, has announced the LinkSwitch-4 family of CV/CC primary-side regulated (PSR) switcher ICs. The LinkSwitch-4 product family features an advanced adaptive base and emitter switched drive scheme for bipolar junction transistor switches (BJTs) that substantially improves power conversion efficiency and eliminates reliability concerns due to secondary breakdown.
 
The new family of devices targets chargers and adapters required to meet stringent new efficiency rules from the US Department of Energy (DoE) and European Code of Conduct (CoC), both of which are scheduled to come into force in January 2016. The new DoE rules, known as DoE-6, require efficiency compliance measurements to be taken at the end of the charger USB cable; LinkSwitch-4 exceeds the requirements while using a low-complexity Schottky diode secondary, even for high-current 1.5 A and 2 A smartphone chargers.
 
LinkSwitch-4 ICs incorporate a multimode PWM/PFM controller with a quasi-resonant switching strategy to maximise the efficiency, meet <30 mW no-load and at the same time maintain fast transient response. A high operating frequency of up to 65 kHz enables transformer size to be minimised, and the minimum peak current is fixed to improve transient load response. Devices compensate for a number of factors including: transformer inductance tolerances; input line voltage variations; cable voltage drop; and external component temperature variations. Very accurate IC parameter tolerances are maintained using proprietary trimming technology.
 
Commented Mike Matthews, Power Integrations’ vice president of product development: “The LinkSwitch-4 controller’s adaptive base and emitter switched drive scheme boosts switching performance and delivers higher efficiency than is possible using existing BJT or MOSFET switchers. The technique also eliminates secondary breakdown associated with BJTs and reduces sensitivity to variation in current gain, allowing use of very low cost BJTs. The adaptive base-emitter switched drive technology not only provides design and manufacturing flexibility in the choice of BJT transistors by dynamically optimizing BJT switching characteristics but also dramatically improves the reliability of BJTs based solutions.”
 
Suitable for chargers for cell/cordless phones, PDAs, MP3 and other portable audio devices, adapters, and more, LinkSwitch-4 ICs are available in SOT-23-6 and SO-8 packages. Devices cost $0.16 to $0.25 in 10,000-piece quantities. 

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