The new ZVS power modules from Vicor offer high efficiencies at high temperatures.

Vicor has announced the latest member of their PI332x-00 family of high-input-voltage DC/DC ZVS buck regulators. Known as the PI3325-00-LGIZ, this power module, like other modules in the PI332x-00 series, has a high-performance ZVS (zero-voltage switching) topology, which, according to the datasheet, increases POL (point of load) performance and provides "best in class power efficiency." These ZVS-type step-down (or buck) regulators integrate the controller, the power switches, and many of the support components, all within a high density SiP (system-in-package). As discussed in this Digi-Key article, ZVS is a method of controlling a regulator's switches (i.e., MOSFETs) in a manner that increases the regulator's efficiency and reduces the amount of EMI (electromagnetic interference) originating from the regulator.

This PI3325-00-LGIZ power module accepts input voltages ranging from 14 to 42 V and supplies up to 20 A at output voltages from 4.0 to 6.0 V. As can be seen in the figures below, this device is offered in a unique 110-pin LGA package measuring 10 × 14 mm. And while all these pins may appear overwhelming at first inspection, many of them are grouped together in pin blocks. So making the proper connections should be fairly straightforward.

 
The PI3325-00-LGIZ power module is offered in a unique SiP (system-in-package). Image taken from the datasheet (PDF).
 

There are many pins (more properly called “lands”), but don’t worry, most of them are grouped into only a few nets. Diagram taken from the datasheet (PDF).

 

Is Said to Deliver More vs. the Competition

According to Vicor, "A regulator is only as good as the power it can deliver in the actual environment it will be used in," and they show us (see the figure below) how their ZVS regulators outperform the competition with regard to delivering power at higher temperatures, with higher efficiency, and in smaller packages.

 

Vicor illustrates how their ZVS regulators outperform the competition. Images courtesy of Vicor.com.

 

The plots below convey the efficiency of this power module at three board temperatures: 25°C, 90°C, and -40°C. As you can see, the performance is quite consistent despite the large variations in temperature.

 

Efficiency for different temperatures and input voltages, from the datasheet (PDF).

 

A Few External Components Are Still Required

While many of the components of this power system are contained inside the module's package, a few external components (an inductor, two voltage-selection resistors, and filter capacitors) are still required for operation. Fortunately, Vicor provides guidance for selecting these components, along with solid layout tips and diagrams.

With regard to selecting the inductor, Vicor does not simply suggest an inductor, but rather they mandate which one to use for achieving peak efficiencies; see Table 3 (on page 21… there’s also a Table 3 on page 18). For convenience, I've included the inductor information in the figure below. As can be observed, Vicor has called out a specific inductor, including manufacturer and part number. Hopefully this seemingly single-source part is not terribly expensive, and is readily available!

 

Vicor has recommended a specific inductor for achieving maximum efficiency. Information taken from the datasheet (PDF).

 

Lots of Current

The PI3325-00-LGIZ maxes out at 20 amps; if your application requires more than 20 A, you have the option of using up to three of these modules in parallel. However, as described in the section entitled Parallel Operation (page 21), the EAO (Error Amp Output), TRK (Soft Start and Track Input), EN (Enable Input), and EAIN (Error Amp Inverting Input) pins all require special care. So be sure to check out this section for more information regarding parallel operation. The figure below shows two modules connected in a parallel fashion.

 

Two ZVS modules in parallel; up to three in parallel is possible, according to the datasheet (PDF).

 

Layout Information

Be sure to take a look at the Layout Guidelines section in the datasheet; it includes explanations, clear diagrams (such as the one shown below), and PCB footprint and stencil recommendations.

 

The datasheet provides PCB layout recommendations with easy-to-understand diagrams.

 

An Evaluation Board Is Available... Maybe for Free

If you'd like to test drive this new ZVS power module, then consider using Vicor's evaluation board (see the image below). In fact, you may be able to get your hands on one for free. Checkout this Vicor website for more information.

 

A ZVS power module evaluation board.

 

Have you had a chance to use one of Vicor’s ZVS converters, or have you received a free evaluation board? If so, leave a comment and tell us about your experiences.

 

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