At APEC 2019, AAC spoke with Renesas's Jeff Strang about a new series of PMBus power modules that feature two innovations they hope will make power design easier for engineers.

Last week, Renesas announced a new family of DC-DC power modules. On the show floor, AAC had the chance to speak with Jeff Strang, Product Line Director for Industrial Power Products, who walked us through what Renesas believes makes these modules exciting.

 

New High-Density DC-DC PMBus Power Modules

Last week, Renesas announced the ISL8210M, IS8212M, ISL8280M, and ISL8282M. Each of the modules has a voltage input range of 5V to 16V, and supply up to 10A or 15A of current. All four of the modules in this new family come in a 12mm x 11mm package and integrate a PWM controller, MOSFETs, and inductor. 

For the curious, the ISL prefix stands for Intersil, which Renesas acquired in 2017. 

 

The ISL8212. Photo by Kate Smith.

 

The ISL8210M and IS8212M, which offer 10A and 15A of output current, respectively, are analog modules and come at a lower price point. Both of these hybrid digital encapsulated modules offer power density of 115mA/mm2 and can reach up to 95% peak efficiency. 

 

The Power of the PMBus

The encapsulated hybrid digital 10-amp ISL8280M and 15-amp ISL8282M include a PMBus digital interface.

According to Renesas, these are the highest-density PMBus-equipped power modules at these current levels available on the market.

As Strang puts it, "The innovation here is that the ones with the digital interface are the highest density PMBus-equipped power modules that you can buy anywhere, at least at these current levels." 

 

The ISL8280M/ISL8282M. Image from Renesas

 

What does that mean for engineers? "[The modules] can talk to a microcontroller and they can talk to a PC for debugging," says Strang. "You can get fault status information. You can synchronize them or you can do on the fly adjustments as you need to."

 

New Packaging Technology for Thermal Management

Thematic to APEC this year was interest in pushing on the evolution of packaging. Many companies are looking to develop inventive packaging solutions to address industry trends, such as shrinking design footprints, and Renesas is firmly in that realm.

"We have what's called the grid HDA, which stands for grid high-density array," says Strang. Gesturing to the tiny chip balanced on his fingers, he continues, "You can see that it's a little grid of little pads there. These are all copper, plated with gold."

 

The grid high-density array (GHDA) of the ISL8212. Photo by Kate Smith.

 

He mentions the copper specifically because of another APEC concern: thermal management.

"The nice thing about these being copper is that they are directly connected to the hot parts inside the chip. So there are power MOSFETs in here. There's an inductor in here. Those will get hot when you're passing a lot of power through them," says Strang. "And there are two ways to get the heat out of the module. You can put a heat sink on top, which is kind of a pain and sort of expensive—you have to glue it on or bolt it on somehow. Or you can pull the heat out through the bottom of the module into the PCB." 

 

Specs for the ISL821xM analog and ISL828xM hybrid digital power modules:

  • Single rail input voltage of 4.5V to 16.5V, with 0.5V to 5V output voltage settings
  • ± 1.5% output voltage accuracy over line, load, and temperature with remote sense
  • Simple pin-strap resistor setting offering 256 output voltage options
  • ISL828xM modules are SMBus/I2C/ PMBus v1.3 compatible up to 1.25MHz
  • Switching frequency options from 300kHz to 1MHz
  • PFM/light load efficiency modes
  • Comprehensive fault protection monitoring voltage, temperature and current

 

Bonus: Other Renesas Demos at APEC

Bidirectional Buck-boost Controllers

First released last fall, the bidirectional buck-boost controllers provide advanced power management solutions for applications that require uninterrupted power supply like industrial settings or data centers. When the power supply to a supercapacitor power bank is interrupted, the bidirectional buck-boost controller executes a direction change on the fly, sending power to the application from a charging bank.

The use-case targeted for these controllers is in data centers, as they are more commonly utilizing a 48V bus with DC supercapacitor backup. Functioning essentially as an uninterruptable power supply (UPS) on a chip, the controller is able to reverse direction very quickly, so there's no latency when power supply changes. 

Renesas claims their buck-boost controllers are the first bidirectional configuration on the market. In the past, configurations have required two different power circuits, one to charge and one to discharge. By utilizing a bidirectional circuit, Renesas has cut the parts required in half, saving board space.

 

Energy Harvesting with SOTB

Ken Imai, Senior Marketing Manager, presented Renesas's silicon-on-thin-buried-oxide technology used in a microcontroller. It creates an insulation layer prevents leakage and reduces power consumption by about 10x improvement over conventional MCUs. This allows SOTB to run on very low power, making it useful for IoT and other applications that require long operation time without battery replacement.

One tradeoff of SOTB is that the insulating layer adds a bit of size to the MCU; however, at 65mm Renesas has found the best balance between preventing leakage and keeping the size small.

 


 

What updates have you seen to packaging technology this year? How much do you worry about thermal management? Share your opinions in the comments below.

 

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