September 28, 2010

Sanken Releases PVRW304 Bypass Diode for Solar Cells
Axial leaded diode realizes 30 A forward current and does not require heat sink

 
Sanken Electric Co., Ltd. announces the release of the PVRW304, a new bypass diode for solar cells. The PVRW304 is an axial leaded diode (φ6.5 body, φ1.4 lead) featuring a withstand voltage of 40 V and a high forward current of 30 A. The PVRW304 does not require a heat sink and can be used in place of conventional heat-sink-attached TO220 package diodes. Samples of the PVRW304 are currently being shipped at a unit price of 100 yen. Mass production is scheduled to begin in January 2011 at an initial scale of 500,000 units per month, to be ramped up to 5 million units per month in fiscal 2012.
   
1. Development background and product overview
  The market for solar cell systems is growing as demand for clean energy rises among today's environmentally conscious consumers.

Solar power generation systems consist of a solar panel on which multiple solar cells are connected in series. One problem with solar panels is that if any section of the solar panel is shaded by a building, tree, or power line, the power output of the solar cells on that section drops, and those cells operate as resistors. This lowers the generating efficiency of the panel as a whole. However, this problem can be prevented by inserting bypass diodes to reroute the current around the low-output cells.

Improving the conversion efficiency of the solar cells tends to increase the output current. This also increases the current flowing through the bypass diodes, causing them to generate a lot of heat. Until now, manufacturers of solar cell systems—particularly crystal solar cells—have solved this problem by using Schottky barrier diodes housed in a TO220 package, which includes a heat sink to dissipate the generated heat. This solution, however, has proven problematic in terms of the labor required to attach the diode, and the restrictions the heat sink places on the board layout.

Sanken has therefore developed the PVRW304, a Schottky barrier diode housed in an axial leaded package and featuring the industry's highest forward current rating of 30 A. Moreover, because the diode uses an optimized barrier metal*, generated heat can be dissipated from the leads.

Using the PVRW304—which does not require a heat sink—therefore increases both layout efficiency and freedom.

* The characteristics of Schottky barrier diodes are formed by the contact between a metal and a semiconductor element. The metal used in the diode is called the barrier metal.
   
2. Features
  (1) Axial leaded package achieving forward current rating of 30 A
No heat sink is required, simplifying board layout.
(2) Low power dissipation (VF = 0.55 V max)
Low power dissipation is achieved because the diode is a Schottky barrier diode with a 40 V withstand voltage.
(3) High heat resistance (Tj = 190℃) * DC flowing in the forward direction, t ≤ 1 h
High heat resistance simplifies thermal design.
(4) Small-scale package
A high forward current rating of 30 A is achieved in a small axial leaded package (body size Φ6.5).
   
3. Major specifications
 
Parameter Symbol Rating Unit
Reverse voltage VR 40 V
Forward current IF(AV) 30 A
Forward voltage VF 0.55 max. V
Junction temperature Tj -40 to +190
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