Green AC/DC
Small, Reliable, Efficient power supply technology
Introduction
Most switchmode AC/DC power supplies rely heavily on input-side electrolytic capacitors to enable continuous output voltage, EMI filtering and surge protection. Techtium’s Small-Cap AC/DC Power Supply (SCAD™) redefines power supply topology to reduce or remove these capacitors, thereby dramatically improving the power supply size, efficiency, reliablility, manufacturability and heat generation.
Techtium’s Small Capacitor AC-DC (SCAD™) Topology
The core of Techtium's innovative and proprietary technology is the more efficient use of capacitors in the circuit. When starting out on this development program, Techtium realized that to make switchmode power supplies smaller and more reliable, the issues caused by these large electrolytic capacitors on the input needs to be mitigated. Techtium's solution was to move these energy reservoir capacitors to the secondary side of the isolation so and to add a second switchmode circuit to control the output voltage and current. This topology allows better utilization of the energy stored in the capacitor, thus reducing the size and cost of these components. It even allows eliminating the electrolytic capacitors entirely for power supplies below 15 watts that do not need long holdup times.
To further allow size reduction and meet customer demand for eco-friendly power supplies, high efficiency and virtually zero no-load standby power features are also encorporated into the Techtium SCAD™ technologies. Together, this new topology allows a long series of benefits for the power supply features, ease of design and manufacturability.
Operation is based on two Techtium ICs - TEC501 or TEC505 controls the primary side, and TEC602 controls the secondary side.
Benefits include:
- Small physical size
- Light weight
- Excellent reliability
- ENERGY STAR compliant standby and efficiency
All these benefits can be translated into reduced lifecycle costs when all factors are included (mechanical design, shipping, maintenance, disposal, etc.)
How it works?
Techtium’s SCAD™ unique Double Burst topology enables efficient use of the reservoir capacitor’s energy and the capacitor’s transfer from the primary side to the secondary side (Techtium's SCAD™ topology uses more than 80% of the capacitor energy comparing to 30% usage in a typical power supply).
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Standard AC/DC:
30% utilization of stored energy
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Techtium's SCAD:
85% utilization of stored energy
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Capacitor total energy: E=CV2/2. Stored energy usage (%) = (Vhi2- Vlow2)/Vhi2
Lowering the working voltage and efficiently using the capacitor's energy allows choosing much more reliable ceramic or tantalum capacitors which are smaller and can endure much higher ripple current.
The reliability (MTBF; FIT, useful life, etc) is much improved in Techtium’s SCAD™ topology as it does not use electrolytic capacitors. Even if a particular application requires an electrolytic capacitor, this capacitor’s work conditions are very mild, thus keeping the reliability high.
Techtium’s topology allows very high work efficiency, small physical dimensions and very low standby power consumption (less than 20 mW). This Power Supply not only meets the ENERGY STAR guidelines but surpasses them.
Due to very low power dissipation (very high efficiency) a smaller size PCB can be used. This enables using Techtium's SCAD™ for new and smaller sized applications, such as embedded power supplies and consumer electronics.
The AC/DC Power Supply is very stable regardless of its input or its output load. The SCAD™ design allows a high and controllable Power Factor, using ceramic / tantalum capacitors (instead of Al electrolytic) allowing greater design flexibility.