Renesas Electronics Corporation (TSE: 6723), a premier supplier of advanced semiconductor solutions, announced the availability of a long-creepage-distance photocoupler, the PS9905, for inverters in applications such as industrial equipment employing the maximum commercial power supply voltage of 690 V or solar power generation systems employing high voltages up to 1,000 V. The new PS9905 device is a photocoupler (compound semiconductor, Note 1) with an external creepage distance (Note 2) of 14.5 mm, exceeding the 13.8 mm specified in safety standards (IEC 61800) covering insulation to prevent electric shock, etc.

A high-speed photocoupler, the PS9924, is also available, which supports internal system communication speeds of 10 Mb/second while providing a long creepage distance of 14.5 mm. Among products with creepage distances exceeding 10 mm, it delivers low power consumption characteristics among the best in the industry, making it ideal for applications requiring both high insulation voltage and low power consumption.

As efforts to reduce CO2 emissions and lower energy consumption in order to protect the environment have advanced, the use of inverters in industrial applications and solar power generation systems has continued to grow rapidly as a way to achieve low-power motor control and reduce power conversion loss. These inverters comprise high-voltage circuit blocks containing power devices such as IGBTs and control circuit boxes containing devices such as microcontrollers (MCUs). Photocouplers are required to drive power semiconductor devices such as IGBTs while electrically isolating the two circuit blocks.

Renesas already mass produces compact photocouplers with a creepage distance of 8 mm for driving IGBTs in inverter circuits. However such systems have come to handle increasingly higher voltages, making it possible to lower the current level, reducing power loss and allowing the use of thinner cables between inverter motors and as power cables. To address this market trend, Renesas released the PS9905 and PS9924 photocouplers for inverters in industrial systems employing 690 V power supplies, use of which is expected to expand further moving forward, and inverters in 1,000 V solar power generation systems. The new photocouplers have a long creepage distance of 14.5 mm to meet applicable safety standards.

Key features of the new PS9905 and PS9924:

• (1) Compliant with safety standards covering inverters for 690 V industrial systems and 1,000 V solar power generation systems (PS9905)

  The IEC 61800 standard requires a creepage distance of 13.8 mm or more for the reinforced insulation (Note 3) of 690 V power supplies and a creepage distance of 10 mm or more for the basic insulation (Note 4) of inverters in solar power generation systems handling voltage levels of 1,000 V. The new PS9905 employs design enhancements that enable a creepage distance of 14.5 mm, easily meeting the safety standard. The insulation voltage is 7,500 Vrms, suitable for equipment with high voltage handling.

• (2) Contribute to more compact inverters (PS9905)

  The new PS9905 can do the work that previously required two Renesas Electronics photocouplers, each with a creepage distance of 8 mm. This results in a reduction of approximately 30 percent in the mounting area. In addition, the newly developed 8-pin surface-mount package gives this high-speed photocoupler one of the smallest mounting areas in the industry among photocouplers with a creepage distance exceeding 10 mm.

• (3) High-speed respond with IGBT photocoupler at 2.5 A output (PS9905)

  The photocoupler employs a light receiving IC fabricated with a BiCMOS process exclusive to Renesas Electronics, enabling it to achieve a low parasitic capacitance (Note 5) while keeping the circuit current (Icc) below 3 mA and delivering short delay times (tPHL, tPLH) of less than 150 ns. High-speed response is among the best in the industry for photocouplers to drive IGBTs with 2.5 A output, allowing for improved output current accuracy after inverter control.

• (4) Low power consumption with a 10 Mb/second high-speed photocoupler (PS9924)

  Optimizing the design of the light receiving IC incorporated into the photocoupler made it possible to achieve a long creepage distance of over 10 mm and substantially lower power consumption. Input current (IFHL) is 5 mA (maximum value) and circuit current (Icc) is 5 mA (TYP). Power supply voltages of 3.3 V and 5 V are supported, and the operating temperature range is a wide −40 to 110℃. The photocoupler can then be used for communication in compact systems where the high mounting density is accompanied by a high-temperature environment.

Renesas believes the new photocouplers will contribute to a trend toward converters with higher voltage handling and greater compactness, which is expected to drive market growth, and the company plans aggressive sales promotion as it continues to develop products to satisfy high-temperature and high-output requirements. Renesas also supports system designers with total solutions combining microcontrollers and IGBTs used in inverters.

(Note 1) Photocoupler:

A photocoupler houses in a single package a light generating element (LED) on the input side, which converts the electrical signal to light, and a light receiving element on the output side, which converts the light into an electrical signal. Since such an optically coupled device conveys the signal from the input to the output side in the form of light, the two sides can be completely isolated from each other electrically.

(Note 2) External creepage distance:

The minimum distance from the high-voltage-side package pin to the low-voltage-side package pin used for connecting the photocoupler, as measured along the resin exterior of the package. A longer distance provides a higher voltage tolerance.

(Note 3) Reinforced insulation:

Insulation which is stronger than basic insulation. The standard requires a creepage distance twice that of basic insulation.

(Note 4) Basic insulation:

Basic insulation for preventing electrical shocks to humans.

(Note 5) Parasitic capacitance:

Unintended capacitance components that arise within the chip due to its physical structure. Also called floating capacitance.