New Power Products Pack A Potent Punch

The mantra behind the latest announcements to hit the power semi market: Up with efficiency, down with costs.

It’s been a busy time in the power semiconductor sector of the electronics industry, as evidenced by a recent flurry of new technology launches. Four of them in particular caught my eye.

First is a development by Renesas Technology Europe that involves metal oxide nitride oxide silicon. Second is a trio of high-performance video amplifiers coming by way of Analog Devices. Third, we head over to Geneva, Switzerland to see what ST Microelectronics has been up to with its SuperMESH3 Power MOSFETs. Finally, there’s a new product offering from California-based power-management company International Rectifier to be unveiled at this year’s Electronica event in Munich.

MONOS Matters
So, what’s behind this intriguing development from Renesas Technology that uses MONOS (metal oxide nitride oxide silicon) technology? Called the SH7286, this is the company’s first SuperH product offering up to 1Mbyte of MONOS embedded flash memory (Fig. 1). It’s designed for the high-end drive, ac servo, and general-purpose inverter markets.

Typical code size for a high-end drive or inverter application in Europe currently resides somewhere around 384kbytes of code, but it’s growing at an alarming rate. The shape of motor-control applications is also changing from a dual MCU to a single MCU solution, which is putting added pressure on the code size.

In turn, European system designers are considering the use of external memories and ROM-less devices. The reason is simple—microcontrollers with up to 1Mbyte of embedded flash and dedicated motor-control peripherals weren’t available beforehand.

The SH7286 device incorporates an MTU2 timer unit with six channels of 16-bit timers, support for up to 16 input-capture/output-compare functions, and a three-phase PWM capability for electrical motors. Additional motor-control features are enabled by a quadrature encoder feedback capability and a special channel that can measure dead times at the power stage.

The MTU2 also offers additional safety features with its Port Output Enable (POE) pins. These provide a faster and more deterministic response time to ensure safe, quick shutdown of the motor.

The integrated circuit includes three ADCs with four channels each, 12-bit resolution, and 1.0µs conversion time. Each ADC can be triggered by the MTU2 with an additional defined delay time to support algorithms such as single-shunt motor drive.

For a product that’s able to combine the functionality of the two MCUs in a motor-control system, communications becomes an obvious and important question. Thus, the SH7286 offers a CAN module, USB 2.0 module, five SCI channels, one SSU (synchronous serial communication unit) channel, and one IIC channel.

The device makes use of the SH-2A core. This core, an enhanced version of Renesas’ SH-2 core with a superscalar architecture, has two execution units in the pipeline. Consequently, two instructions can be processed concurrently and code can be executed up to twice as fast as the CPU clock. In addition, its Harvard-based architecture ensures that no bus conflicts occur between instruction fetch and data access.

The core’s CPU registers are now arranged in "banks," with the 19 registers being mirrored 15 times. Thanks to this technique, an interrupt subroutine can utilise a second set of registers, leaving the current ones ready for use upon return from the interrupt subroutine. This means that the registers don’t need to be popped onto and back from the stack, providing a quicker return from the interrupt subroutine. As a result, the response time to an interrupt request (IRQ) is as quick as a simple branch instruction—just six cycles!

Picture-Perfect Amplifiers
For HD TV and video apps that need a power-efficient, high-performance, rail-to-rail operational amplifier, Analog Devices came up with three high-performance video amplifiers (Fig. 2). These additions to ADI’s Advantiv advanced television solutions portfolio are designated ADA4420-6, ADA4855-3, and ADA4856-3.

The ADA4855-3 and ADA4856-3 provide single-supply, rail-to-rail operation with flexibility for passing a range of signals, while cutting system cost. These devices deliver advanced video performance, driving a 150Ω load with 0.01% differential gain error, 0.01° differential phase error, and 0.1dB flatness out to 63MHz and 85MHz, respectively. Also, the ADA4855-3 offers a 400MHz, -3dB bandwidth at gain of 1, while the ADA4856-3 delivers 220MHz at a fixed gain of 2.

Using a single 5V power supply, the ADA4855-3 and ADA4856-3 consume only 7.7mA per amplifier, while delivering up to 40mA of load current. On-chip power-down features reduce supply current to 1mA.

The ADA4420-6 video filter offers advanced performance, flexibility, and power efficiency for engineers involved with high-definition TV and high-definition (HD) component video subsystems. By integrating a number of buffers, discrete components, and six independent filter channels—three for SD (Y/C, CVBS) and three for HD component (YPbPr or RGB) signals—the ADA4420-6 turns into a single-chip solution that supports HD, SD (standard definition), S-Video, and composite video signals.

First Of A New MOSFET Family
Over in Geneva, STMicro-electronics believes it’s increased the ruggedness, switching performance, and efficiency of power MOSFETs for lighting ballasts, where they’re used in the PFC and half-bridge sections, as well as in switching power supplies. How is this so?

The use of SuperMESH3 technology with lower on-resistance guarantees higher efficiency. In addition, due to their good dv/dt performance and higher breakdown-voltage margin, SuperMESH3-based devices enhance reliability and safety.

STMicroelectronics can make the dv/dt performance claim because SuperMESH3 technology combines strip topology with an optimised vertical structure. This translates into increased reliability and safety in lighting and other consumer electrical applications. All of the SuperMESH3 devices are 100% avalanche tested, and also incorporate Zener protection.

The first SuperMESH3 devices are the 620V STx6N62K3, followed by the STx3N62K3, also at 620V, as well as the 525V STx7N52K3 and STx6N52K3 (Fig. 3). SuperMESH3’s savings in on-resistance help reduce RDS(on) in DPAK packages to 1.28Ω in the STD6N62K3 at 620V and 0.98Ω in the STD7N52K3 at 525V, boosting operating efficiency in applications such as low-energy lamp ballasts.

Interestingly, the new technology also cuts reverse-recovery time (Trr), gate charge, and intrinsic capacitance. Those benefits ultimately lead to improved switching performance and enabling higher operating frequencies.

Power Amplifier Reference
International Rectifier (IR) will be attending the Electronica exhibition, and plans to use the show to demonstrate its new Class D audio power-amplifier reference design, the IRAUDAMP7, for 25W to 500W scalable output power applications (Fig. 4).

There are two versions of the reference design. The IRAUDAMP7S two-channel, 120W half-bridge design provides 91% efficiency at 120W in Class D stage, 8Ω, and a THD+N of 0.005% at 1kHz, 60W, 8Ω (both typical). It contains the IRS2092S in an SOIC package with surface-mount components. The IRAUDAMP7D reference design features the company’s IRS2092 protected digital audio driver IC in a DIP16 package together with through-hole components.

Both reference designs are paired with the IRFI4019H-117P digital audio dual MOSFET to enhance scalability. They are wave-solder-process-compatible.

IR believes the IRAUDAMP7 will provide designers with quick and easy scalability. For example, a 125W design can be functionally scaled to 60W within minutes simply by changing seven of the 50 components that are required on a single-layer board.

The IRAUDAMP7 incorporates critical protection features. These include protection for overcurrent, overvoltage, undervoltage, dc, and overtemperature. Among its "housekeeping" functions, designers will observe a ±5V supply for analog signal processing for the preamplifier and a +12V supply (VCC) referenced to -B for the Class D gate driver stage.

According to the company, the reference designs are available immediately. Pricing as of this writing is $199 (U.S.).

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