Qorvo Debuts Single-chip Management ICs for 20-cell Battery Systems
To enable the move from combustion engines to battery power for lawn equipment, e-mobility, and similar designs, Qorvo has released one-chip battery management ICs for 20-cell battery-powered systems.
This week the Embedded World 2023 trade show—arguably the most significant industry gathering in the embedded technology space—runs from March 14 to 16 in Nuremberg, Germany. We kick off our coverage of Embedded World this week, with Qorvo announcing what it claims as the industry’s first pair of single-chip controller devices for 20s battery packs—packs with up to 20 cells in series.
The PAC22140 and the PAC25140 battery management controllers are targeted for a variety of industrial, e-mobility, and battery backup designs.
In this article, we look at the trends driving the need for these devices—the PAC22140 and the PAC25140, we look at the chips’ key features, and we share insights from our interview with Qorvo execs Brian McCarthy, senior product line manager, and John Carpenter, product development manager.
The Shift Away From Combustion Engines
According to McCarthy, these new devices fit into the company’s history going back before Qorvo acquired Active Semiconductor in 2019. Active Semiconductors’ line of PAC (Power Application Controller) products provide integrated microcontroller (MCU) intelligence for motor control. And that motor controller line has continued under Qorvo’s time, with over 30 production IC products.
Driven by technology advancements in batteries and government regulations, industrial consumer gear is moving to battery-powered engines.
Now, Qorvo is moving that same idea into the battery management space. While a lot of battery management technology discussion in the industry today is focused on automotive batteries, here Qorvo is targeting a trend toward electrification in the diverse segment of systems like large lawn equipment, e-mobility, battery backup gear, and other systems of that scale.
“We really started looking at these trends of motor technology moving from combustion engines to brushless DC motors,” says McCarthy. “At the same time, you've got all the AC powered and gas powered systems moving to battery powered.” McCarty also points to key industry trends, such as advancements in battery technology and government regulations. “In California, for example, the state is moving toward outlawing combustion engines for larger lawn equipment,” he says.
“What we see if you look at the non-automotive space is this trend towards higher voltage battery packs,” says McCarthy. “While in the automotive space there are 400 V and 800 V batteries, in the industrial consumer side that we’re talking about, you tend to see 20 V packs, but those are increasing to higher voltages. Higher performance equipment is moving to battery powered, and it's something that we think is an opportunity for us.”
The Importance of Cell Balancing Grows
Battery cell balancing is a critical piece of the puzzle when it comes to battery management. And the problem gets more acute as the industry moves to higher cell counts. “With higher cell counts, the probability of one cell being mismatched to the other cells goes up,” says Carpenter.
“With 5s batteries, a lot of people originally didn't do cell balancing because they could match the cells fairly well and then the variation wasn't so bad,” he says. “But as manufacturing of the cells have gone into other locations, the variation between the cells has gotten worse. The combination of manufacturing variation plus a higher cell count really means you have to include cell balancing moving forward.”
Embedded MCU-controlled intelligence is key to implementing that cell balancing. “We have currently implemented a simple algorithm,” says Carpenter. “It basically says, ‘how many cells do you want to balance?’ We allow every other cell to be balanced. So, in theory, you could balance a 10- and a 20-cell pack all at once.”
“The firmware handles it and you can move to more sophisticated algorithms as designs evolve—different types of balancing that could be achieved, all digitally controlled.”
An MCU Side and an Analog Front End Side
Aside from the PAC22140 having an Arm Cortex M0 core, and the PAC25140 having an Arm Cortex M4F core, the two devices share a lot of the same internal features. The devices are divided into a digital MCU side and an analog front-end side.
On the analog battery front end (ABFE) side, the configurable power manager is configurable for 10s to 20s battery applications, ranging from 18 V to 180 V. Integrated cell balancing FET drivers support 10s to 20s cell balancing. Both devices have two 16-bit sigma-delta ADCs—one for current sensing, the other for cell balancing. A single-supply 145 V buck DC-DC controller generates a 5 V system rail to power the device. Meanwhile, an integrated charge pump supports the charge and discharge FET drivers.
Both the PAC22140 and the PAC25140 are divided into a digital MCU side and an analog battery front end (ABFE) side.
On the digital MCU side, the PAC22140 and PAC25140 offer some different features. The 5 MHz Arm Cortex M0-based 22140 boasts a 10-bit 2.5 MSPS SAR ADC, while the 150 MHz Arm Cortex M4F-based 25140 embeds a 12-bit 2.5 MSPS SAR ADC. For memory, the 22140 provides 32 KB of flash and 8 KB SRAM, while the 25140 serves up 128 KB of flash and 32 KB of SRAM. Both devices provide UART, SPI, and I2C/SMBus peripherals, but the 25140 also adds CAN bus.
The PAC22140 and PAC25140 provide a low-power hibernate mode of less than 3 µA. Qorvo says this enables long storage time with wakeup from the push button, timer, or charger detection.
The integrated buck controller on the devices helps with thermal issues. That’s done by supporting the system with a 5 V regulated supply up to 225 mA. An integrated 3.3 V LDO supplies up to 90 mA for powering additional peripherals. An analog MUX is connected to the SAR ADC to enable safety checks on internal nodes.
Qorvo says the PAC22140 is in volume production today in a 9 mm × 9 mm, 60-pin QFN package. Meanwhile, the PAC25140 is sampling now, with production scheduled for April 2023. The 22140 is packaged in a 10 mm × 10 mm, 68-pin QFN package.
Qorvo is showcasing these products this week at its Embedded World booth 4-578.
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