Geneva – STMicroelectronics (NYSE: STM) has introduced the VIPer17 off-line switched-mode converter, which integrates an 800V avalanche-rugged MOSFET as well as numerous features to save external components and ensure efficient operation during standby mode. Constant-current operation with an adjustable set point allows use with all mains voltages in SMPS (switched-mode power supply) designs up to 12W.
By integrating a high-voltage startup-current generator as well as essential protection functions, VIPer17 eliminates the need for external sensing components, as well as a startup resistor. Protection features include accurate, adjustable over-voltage and overload protection, hysteretic over-temperature protection, and two levels of over-current protection. Detection of a fault initiates the device’s auto-restart function, which prevents damage to the power supply or the load. An integrated soft-start function, active at startup or after a fault, reduces stress on the secondary diode and also helps prevent transformer saturation.
Under light-load conditions, such as when the powered equipment is placed in standby mode, the VIPer17 automatically enters burst mode to maximize efficiency. By achieving high efficiency at sub-1W loads, VIPer17 helps designers reduce system standby power and average power consumption to satisfy energy-saving initiatives such as Energy Star and Blue Angel. The device’s typical standby power consumption is 50mW, which can be reduced to 30mW when used in an optimized transformer design.
PWM operation with switching-frequency jittering also eases design challenges by reducing EMI at the switching frequency. This further extends the cost savings VIPer17 delivers in applications such as home appliances, consumer products and lighting systems, by reducing requirements for shielding.
The chip comes in a low-cost 7-pin through-hole DIP package (N type) and in a surface-mounting SMD package (D type). The physical layout of the device incorporates a double island for the power MOSFET and controller, to maximize reliability under a wide range of operating conditions.
Available variants are the VIPER17LN / VIPER17LD or VIPER17HN / VIPER17HD with fixed switching frequency of 60kHz or 115kHz, respectively. The new devices join ST’s existing VIPER12 and VIPER22 converters, and are available immediately for production orders, at $0.37 in quantities of 10,000 units.
::Design World::
Filed Under: Appliance engineering + home automation, Semiconductor, Converters (electrical) AD + DA • transformers, Electronics • electrical
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