Motor-drive IC cuts safety-shutdown time in half

-- EDN, 11/23/2000

A linear, current-sensing IC from International Rectifier has built-in overcurrent shutdown for motor-drive applications (Picture). The IR2172 is rated at 600V and handles 230V, three-phase ac-inverter, or brushless-dc industrial motor drives. The IC has a 1.5-µsec overcurrent-shutdown feature with a wired-OR connection capability directly to a µP or DSP chip. Conventional linear current-sensing opto- or Hall-effect-sensing systems have typical shutdown times of 3 to 4 µsec. Motor-drive circuits using opto or Hall sensors require two external comparators and a level-shift operational amplifier to provide the same function as the IR2172. The IC uses a PWM output and runs off a bootstrap supply instead of a dedicated secondary supply. The motor driver comes in two industry-standard compact packages: SO-8 and an eight-pin DIP. The price is $3.55 (10,000).

International Rectifier, www.irf.com.

at www.rscahners.ims.ca/ednmag.

-by Bill Travis