Simplifies Development of More Compact Inverters for Industrial Equipment and Solar Power Generation Systems
13 May 2011
TOKYO, May 13, 2011 — Renesas Electronics Corporation (TSE: 6723), a premier supplier of advanced semiconductor solutions, today announced the availability of the company's first photocoupler product the “PS9402”, with an integrated insulated gate bipolar transistor (IGBT, Note 1) protection function. The PS9402 photocoupler comprises a gallium-aluminum-arsenide (GaAlAs) LED as the light emitting element, a photodetector IC, and an IGBT protection circuit. It is designed to drive IGBTs used in inverter devices for purposes such as motor control. Use of the new photocoupler facilitates the design of IGBT peripheral circuits and enables IGBT direct drive up to the 1,200 volt (V) and 100-ampere (A) class. The compact 16-pin SOP (Small Outline Package) contributes to system compactness.
A photocoupler integrates in a single package a light emitting element (LED) on the input side, which converts an electric signal into light, and a light receiving element on the output side, which converts light into an electric signal. It is an optical coupling device that completely isolates electrically the input and output sides by using light for signal transfer. Photocouplers are used in the inverter circuits of industrial equipment and in home appliances to protect the circuits between electronic devices or to shut out noise by electrically isolating the input and output blocks.
General-purpose inverters and inverters for solar power generation systems are a fundamental technology employed in recent years to reduce environmental impact by cutting carbon dioxide emissions and reducing power conversion loss to save energy, and the market for these inverters is expected to continue to grow moving forward. The inverter circuit comprises a high-voltage circuit block incorporating power devices such as IGBTs or MOSFETs and a control circuit block employing components such as a microcontroller (MCU). Photocouplers designed for use with IGBTs or MOSFETs are needed to electrically isolate the two circuit blocks. An IGBT drive coupler is typically used for drive control of an IGBT, but a protection circuit is also needed to safeguard the IGBT. This has tended to complicate the overall system design.
The PS9402 photocoupler simplifies system design and contributes to greater compactness by integrating the protection circuit that previously had to be added as an external component.
Key features of the PS9402 photocoupler:
(1) Integrated IGBT protection circuit providing functionality such as short circuit detection
When a fault (short circuit) occurs in the IGBT connected to the photocoupler, the collector-emitter voltage of the IGBT rises and may damage the device. The PS9402 has a function that detects when such a collector-emitter voltage rise occurs and turns off the IGBT. It also incorporates a soft turnoff function that suppresses the generation of noise when the IGBT is turned off. A fault signal is output to the MCU to indicate that an abnormal shutoff has occurred, and an auto-reset function performs recovery automatically after a specified duration (minimum 5 microseconds) has elapsed after the fault was detected.
Since these protection circuits are built into the PS9402 photocoupler, the design of the system is simplified and it can be made more compact overall.
(2) Integrated active Miller clamp circuit to prevent IGBT malfunctions
When the IGBT connected to the photocoupler turns off, current flow to the collector-gate capacitance (Miller current) can generate a gate voltage that causes a malfunction. The active Miller clamp circuit built into the PS9402 absorbs the Miller current, averting malfunctions by preventing the gate voltage from rising.
(3) High-speed and low-power operation
Renesas Electronics' exclusive BiCMOS process is employed for the light receiving IC, resulting in reduced parasitic capacitance (Note 2), shorter delay time (tPHL and tPLH ≤ 200 ns), and reduced circuit drive current consumption (Icc ≤ 3 mA). These contribute to an increase in the precision of the inverter control circuit and reduced power consumption. They also enable greater system compactness because keeping circuit current levels low means a smaller power supply can be used for the system driven by the IGBTs.
Renesas Electronics positions the new PS9402 photocoupler as a product that can contribute to simplified development and greater compactness in inverter systems, for which the market is expected to continue to grow in future. The company plans to continue to develop new high-temperature and high-output product versions.
(Note 1) Insulated Gate Bipolar Transistor (IGBT):
Insulated gate bipolar transistors are used in large-current switching applications requiring high voltage tolerance.
(Note 2) Parasitic capacitance:
Unwanted capacitance components generated by the internal physical structure of the chip. It is also referred to as floating capacitance.
Pricing and Availability
Samples of Renesas Electronics' new PS9402 photocoupler is available now, priced at US$6 per unit. Mass production will start in 2H, FY2011 and will reach a scale of 1,000,000 units per month. (Pricing and availability are subject to change without notice.)
About Renesas Electronics Corporation
Renesas Electronics Corporation (TSE: 6723) delivers trusted embedded design innovation with complete semiconductor solutions that enable billions of connected, intelligent devices to enhance the way people work and live. A global leader in microcontrollers, analog, power, and SoC products, Renesas provides comprehensive solutions for a broad range of automotive, industrial, infrastructure, and IoT applications that help shape a limitless future. Learn more at renesas.com. Follow us on LinkedIn, Facebook, Twitter, and YouTube.
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