Using synchronous buck regulators to meet stringent eco-design targets

With today’s mounting global environmental concerns, government agencies have adopted strict standards that limit the energy consumed by modern electronic products in standby mode. The European Commission has adopted a 1W standby-power initiative to be met by 2010 which will be further lowered to 0.5W by 2013. Tight standby-power requirements are, of course, nothing new to handheld product designers. Thus, regardless of the end product, engineers are challenged to deliver the increased product performance with each successive generation. This includes reduced product cost and increased operating and standby efficiency. A challenge that has been met with Micrel’s family of HyperLight Load™ synchronous buck regulators.

The requirement for high efficiency in all operating states has led to a system performance on-demand strategy wherein power consumption can be scaled up or down as needed to conserve power. Therefore, today’s power supplies must efficiently accommodate a wide range of highly dynamic load currents. Complicating matters further, smaller logic process geometries are driving core and I/O supply voltages to even lower levels. This, in turn, increases the difficulty of maintaining proper operating voltages. For example, a 1.2V core with a ±5% operating supply tolerance has just a ±60mV window that must not be exceeded regardless of board-resistance losses, load current, ambient temperature and input-voltage variations. Assisting engineers to manage these concerns is Micrel’s new family of HyperLight Load synchronous buck regulators which offer the industry’s best combination of excellent efficiency across the entire load range, leading transient performance, and extremely small solution size.

 

 

Micrel’s patented HyperLight Load solutions deliver full-load efficiencies greater than 93% and light-load efficiencies of up to 88%. The high 4MHz or 8MHz operating frequency of the architecture also keeps output voltage ripple down to 3mV at full load, delivers industry-leading load-transient performance (Figure 1) and minimises external-component sizes. Output voltage accuracy is an impressive ±2.5% over the operating temperature range of -40ºC to 125ºC. Available in output currents from 400mA up to 2A, Micrel’s family of HyperLight Load synchronous buck regulators operate from a 2.7V to 5.5V input-voltage range suitable for a single-cell Li-ion, 3.3V DC rail or 5V DC power source. Best of all, the proprietary HyperLight Load architecture reduces silicon overhead thereby allowing the devices to be attractively priced.

 

 

Some members of the HyperLight Load family offer other unique features. Delivered in a 2mm x 2mm MLF® package, the MIC23150 is the smallest 2.0A synchronous buck regulator on the market. The 600mA MIC23051 offers an output voltage-scaling feature that reduces power in standby mode and improves performance in active mode. The 600mA MIC33050 takes feature integration another step further, simplifying design by integrating the power inductor within a 3mm x 3mm MLF® package. As with many other members of the family, the 400mA MIC23030 requires just three external components (Figure 2) consuming less than 29mm2 of board space.

While the European Commission has recently adopted the 1W standby-power mandate, the United States already has set this standard in place for many household and office appliances through the widely-adopted Energy Star programme. Globally, standby-power limits will only decrease as time goes on while market forces and customer demand push product performance and features ever higher with lower costs. The HyperLight Load family of regulators all offer the performance and advanced features that can meet the industry’s evolving power needs.

 

Note: HyperLight Load is a trademark of Micrel, Inc. MLF is a registered trademark of Amkor Technology.

 

Micrel / MIC23x50 MIC2303x