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Sanken Developed a Compact Circuitry to Eliminate LED Flickering
- A Single Converter Removes All Ripples -

February 25, 2013

Sanken Electric Co., Ltd. announced today that it developed a compact circuitry that completely eliminates small current variations, known as "ripples", that causes LEDs to flicker. Sanken plans to offer the use of this patented circuitry together with purchase of its LED driving and controlling ICs to expand its LED-related business.

1. Background of Development

LEDs require direct current. LED lighting equipment therefore includes a circuit, called converter, to convert the alternating current, or "AC", supplied from the outlet to direct current, or "DC".

There are two methods used for electric power conversion: a one-converter single-stage method and a two-converter dual-stage method. The one-converter method requires fewer parts and is therefore more efficient. However, because ripples remain in the current, the LEDs tend to flicker. This has led to complaints about eyestrain and other negative effects on human health.

The two-converter method, on the other hand, reduces remnant ripples. This is because after AC has been converted to DC by the first converter, it is then "converted to DC again" by the second converter to get uniform direct current. This method is commonly employed in long LED tubes and ceiling lights.

However, the two-converter method has the drawback of suffering a large loss because the power must be converted twice. It also requires more parts.

2. Features of the new circuit

Sanken has succeeded in developing a circuit can achieve zero ripple by using the one-converter method. By adding only a few of simple components such as an operational amplifier and a MOSFET, the circuit eliminates LED flickering while maintaining high efficiency. (Patent granted.)

To develop this circuit, Sanken has applied its proven power circuit technologies, especially those in the field of switching power supplies. This development exemplifies the technological edge that Sanken has accumulated through manufacturing a broad lineup of products, from the most upstream AC/DC power supplies to the ultimate application of LED lighting fixtures.

3. Benefits of the new circuit

The new circuit enables a 30% reduction in the number of parts required in an LED lighting system, contributing to lower production costs.

The circuit board is also more compact in size. Because a two-converter circuit requires more space, some developers of small LED lamps had decided to put up with a certain amount of flicker in order to save space. These developers can now eliminate LED flicker while retaining a small board size.

Also, because the new circuit helps improve efficiency, the lighting equipment can realize better energy savings.

4. Business expansion

Sanken plans to offer the use of the new patented circuit together with its lineup of LED-related ICs such as drivers and/or controllers. The company believes that this will lead to an increase in LED driver IC sales, which are forecast from reach two million units per month in fiscal 2013.

- Reference data -

One-converter method