Low EMI DC/DC Regulator Helps Engineers Meet Ever-Tightening OEM Standards

November 14, 2019
ARG81800 Regulator

Ultra-Low Iq Supply Current Ideal for “Keep-Alive” Applications

Allegro MicroSystems, a global leader in power and sensing solutions for motion control and energy efficient systems, today announced the launch of the ARG81800—a robust, ultra-low Iq, low EMI DC/DC regulator ideal for keep-alive supply applications. The device sets a new standard, introducing features that help engineers easily achieve tightening OEM standards, such as:


  • Ultra-low quiescent current mode
  • 150°C operating temperature - for demanding automotive or industrial operating conditions
  • Pin open/short and component faults
  • Unique EMC reductions achieved by incorporating Spread Spectrum frequency modulation (dithering) to a non-dithered external SYNC clock as well as providing a dithered clock output to be used for other converters in the system

“This is not just another buck—the ARG81800 is at the forefront of technology,” explains Mark Gaboriault, Marketing Director at Allegro. “The features that we have added solve real-world challenges for our customers.”


Pass the “airport test”

As electrical content in cars continues to increase, so does the continuous draw of keep-alive systems on the battery. Components must be able to pass the “airport test”—drawing as little current as possible so that the battery can still start the car after an extended period (such as a vacation).Similarly, battery operated industrial systems must limit battery drain to extend service period.


The ARG81800 DC/DC regulator draws just 8 μA, from VIN while regulating 3.3V or 5.0Vout at no load. In comparison to the typical ~100uA budgeted for automotive battery-powered subsystems, this low Iq solution frees up significant overhead to be allocated to other current draws that may occur in the system, allowing more design margin.


Pass EMC

Passing EMC can be a time-consuming, expensive and frustrating process. With extremely low EMI, the ARG81800 is designed to make it easier to pass—the first time around.


“The onus of passing EMC has historically been solely on our customer,” explains Gaboriault. “We embraced the opportunity to offer solutions that make it easier for our customers to meet their EMC requirements, including reference designs and design notes.”


The ARG81800 is capable of wide switching frequency up to 2.4 MHz to avoid critical “keep out” zones (e.g., the AM band), as well as frequency dithering and slew rate control to minimize switching noise. It also offers unique “dithering-on-sync” CLKOUT, which can be used for other switching converters in the system.


Designed for Robustness

Pin opens and pin shorts happen, but they don’t have to ruin the entire board. Robust IC design in the ARG81800—including pin open/short and component faults—protects against IC and PCB damage during manufacturing and eliminates associated scrap costs. The 150°C Tj operating capability makes the ARG81800 suitable for harsh underhood and industrial automation applications.  A power-good output signal with rising-edge delay makes system power sequencing easier and provides diagnostic coverage.


The ARG81800 is supplied in a low profile 20-pin wettable flank QFN package with exposed power pad. Samples and evaluation boards are now available.