If point-of-load (POL) regulators were small and efficient enough, you could just stick them inside the package with a processor or FPGA chip and think back to the days when chips simply ran on 12- or 5-V power bussed around a circuit board. In one stroke, all of those tiresome power design issues of sequencing and loop response would be lifted from the circuit-designer's shoulders and turned over to the chip makers.
Something like that scenario got a little closer late last month, when Enpirion announced its EP53x2Q product family. Enpirion is the only supplier to integrate a planar output inductor, in addition to the switching MOSFETs, within its voltage converters. The only external components required are a pair of 10- to 60-µF output filter capacitors.
All three members of the EP53x2Q family come in 5- by 4- by 1.1-mm QFN packages and differ in their output-current capacity— 500, 600, and 800 mA (see the figure). Typical output voltage ripple is 5 mV p-p. The small package footprint arises from a 5-MHz switching frequency. That high frequency is also what allows the use of a planar inductor within the tiny module.
The input voltage range is 2.4 to 5.5 V. Standby current is less than 1 µA. Output regulation is 2% over line, load, and temperature.-A three-pin voltage-select scheme enables the circuit designer to chose from one of seven predefined voltages between 1.2 and 3.3 V. It's possible to switch between levels on the fly at 3 mV/µs. Alternatively, an external divider may be used to set a constant output voltage.
I must stress that at this time, Enpirion's POLs aren't going inside any chipmakers' packages. Yet Paul Greenfield, Enpirion's vice president of marketing and applications, says that some discussions are under way. That next step may hinge upon developing a coil with an equivalent inductance for a smaller footprint than the planar approach allows, leading to an even smaller footprint for the POL.
Meanwhile, the EP53x2Q power devices are available immediately. Pricing in quantities of 1000 units is $1.61 for the 800-mA version, $1.55 for the 600-mA version, and $1.50 for the 500-mA version.