Cirrus Logic Develops Industry's Highest Current PWM ICs For Driving Mid-Range Brushless and Brush DC Motors

Cirrus Logic Inc. (Nasdaq: CRUS) has introduced the Apex Precision Power^™ SA306-IHZ and SA57-IHZ, the industry’s highest-current pulse width modulated (PWM) ICs targeted at the fractional horsepower DC motor drive market. For the first time, designers can choose a single-packaged solution for driving three-phase brushless DC motors, or brush DC motors, in the <9 V to 60 V supply range. The ICs target motor control circuits used in industrial applications, such as factory and office automation, robotic controls, product handlers, as well as aircraft seating and positioning controls in the aerospace and military markets.

Previously, to drive motors requiring current above 3 A continuous, system designers have been faced with developing discrete solutions involving up to 50-60 individual components and requiring up to 70 percent more board space. The SA306-IHZ and SA57-IHZ give customers a simpler, highly reliable IC solution that incorporates ground-breaking performance of up to 5 A of continuous output current (8 A with A-Grade versions), and PEAK output of 17 A, all housed in a 64-pin Power Quad package with a footprint measuring less than two centimeters square. Inside the package, the SA306-IHZ and SA57-IHZ deliver cycle-by-cycle current limit, which provides the unique ability to precisely control motor current in real time for each motor phase.

"With the SA3-6-IHZ and SA57-IHZ Cirrus Logic has achieved performance previously only possible with discrete solutions, thus improving reliability, simplifying design and saving space,” said Greg Brennan, vice president, Cirrus Logic Apex Precision Power business unit. "Now under the Apex Precision Power product brand, Cirrus is developing next generation products like the SA306-IHZ and SA57-IHZ with integrated performance and features previously possible only with discrete solutions.”

Unique Cycle-by-Cycle Current Limit

With their unique ability to control motor current on a cycle-by-cycle basis, the SA306-IHZ and SA57-IHZ allow the power system structure to "partner” with the processor or DSP to control current in real time for each motor phase rather than just settle for limiting the overall current to a safe value. These devices implement current mirrors in each leg of the driver to continuously monitor and regulate motor current in all phases, and compare these levels to a pre-determined "safe” limit. Should current exceed the limit, the drivers will shut down all outputs for the remainder of the switching cycle and re-set the outputs with the start of the next cycle.

An extended benefit of cycle-by-cycle current limit is the ability to soft start the motor by allowing the driver to handle the inrush of start-up current. For both the SA306-IHZ and SA57-IHZ, this functionality negates the necessity to de-rate the driver’s current rating even at 5 A continuous or greater.

In terms of digital interface, the SA306-IHZ and the SA57-IHZ are designed to provide customers with a seamless interface to either a digital microcontroller (MCU) or a DSP. The top side and bottom side output FETs on these PWM drivers can be individually controlled via direct signals from the processor. This communication includes current sensing for each phase. Each current path is supplied as an individual input to the ADC of the processor.

Power Quad Package Delivers Thermal Efficiency

The use of a 64-pin Power Quad package to house both the SA306-IHZ and SA57-IHZ provides customers with the opportunity to increase the thermal efficiency of their motor control designs. By utilizing a cutout in the printed circuit board and mounting the device upside down, the power dissipation capabilities of the IC can be increased by up to 3X versus a standard on-board mounting configuration. This patent-pending approach can also serve to slim the profile of the overall board layout should it be necessary to heat sink the IC. With the driver placed "through” the board, it allows a nearly flush mounting of the heatsink. System designers can take advantage of an extended temperature operating range of -40°C to +125°C with the A-Grade versions of these devices, the SA306A-FHZ and the SA57A-FHZ.

Another important design note for the SA306-IHZ and the SA57-IHZ is the potential for savings on the overall system layout, size and weight. This is made possible by using switching technology to minimize the power dissipation issues. When compared with a linear amplifier, a switching amplifier provides a significant reduction in heatsink size, while allowing the overall operating system to run cooler and thus increase long-term reliability. The SA306-IHZ and the SA57-IHZ also use smaller filter components because they are able to switch at frequencies of up to 100 KHz.

Key Product Specifications

(a) Per unit pricing through distribution may vary

Product Availability, Demo Boards

The SA306-IHZ, SA57-IHZ and their A-Grade versions are in volume production. Evaluation kits with a fully populated demo board, including the IC, are available. Complete product information is online at www.cirrus.com. For technical support, contact Apex Precision Power product support toll-free at 800-546-2739, or tucson.support@cirrus.com.

Cirrus Logic Inc.

Cirrus Logic develops high-precision, analog and mixed-signal integrated circuits for a broad range of consumer and industrial markets. Building on its diverse analog and signal-processing patent portfolio, Cirrus Logic delivers highly optimized products for consumer and commercial audio, automotive entertainment, and industrial and aerospace applications. The company operates from headquarters in Austin, Texas, with offices in Tucson, Ariz., Europe, Japan and Asia. More information about Cirrus Logic is available at www.cirrus.com.

Cirrus Logic, Cirrus, Apex Precision Power and Apex, are trademarks of Cirrus Logic Inc. All other product names noted herein may be trademarks of their respective holders.

A NOTE TO EDITORS: soft copies of this product news release, product data sheets and product visuals are available for download in the "PRESS ROOM” area of the Cirrus Logic website.