Qorvo Hard-Wires Safety Features into Motor Controllers for 44V-72V Power Tools and Appliances

By: José Quiñones, Staff Applications Engineer


Integrating advanced safety in high-voltage tool controllers

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Figure 1: PAC52711


We're all familiar with the pervasive hum of gas-powered gardening equipment in the spring, summer and fall, from hedge trimmers, leaf blowers, chainsaws, and jack hammers, not to mention the droning of snowblowers in the winter. While gas-powered tools have long been a staple for outdoor maintenance, their noise pollution and environmental impact have come under scrutiny in recent years, especially in densely packed suburban areas. 

Some states have even begun to address those noise issues by implementing regulations on gas-powered tools in favor of quieter and cleaner electric alternatives. Washington, DC, has already implemented a strict ban on gas-fueled lawnmowers and leaf blowers, with some cities in Florida, Illinois, Oregon and California following suit. The demand for battery-powered tools as replacements to their gas-driven alternatives has been increasing over the last several years as newer battery technology has been proven a viable alternative to fossil fuels. But what truly powers these electric power tools are the brushless DC motors (BLDCs) that can handle the high voltages needed to keep those tools running efficiently.

Complete, intelligent motor control solutions

Next-gen power tools need updated motors and controllers that can tap the high voltages needed to drive outdoor tools while integrating safety features to protect the user and equipment. This is where Qorvo steps in, with its knowledgeable insight into high-voltage controllers for brushless DC motors. The company's current family of intelligent, highly optimized PAC (Power Application Controller)® SoCs can implement a BLDC or PMSM (permanent magnet synchronous motor) programmable motor controller and driver into a single IC to control today's power tools across voltages ranging from 44V to 600V.

The PAC5xxx series of intelligent controllers can handle the DC brushless motors found in most power tools and pack a 50MHz Arm Cortex®-M0 32-bit microcontroller, a high-speed 10-bit 1µs analog-to-digital converter (ADC) with dual auto-sampling sequencers, flexible clock sources, timers, PWM engine and several serial interfaces. The SoC is also outfitted with a programmable multi-mode power manager, configurable analog front end and application-specific power drivers. 

The multi-mode power manager (MMPM) is like a Swiss Army knife for power management, capable of handling different voltages with efficiency, and includes a multi-mode switching supply controller that can function in either buck or SEPIC mode, along with up to four linear voltage supplies. The application-specific power drivers (ASPD) can take advantage of high-voltage power drivers tasked with specific control applications such as H-bridge, 3-phase, intelligent power modules (IPMs) and general-purpose driving. The configurable analog front end (CAFE) acts as the brain of the SoC and features programmable gain amplifiers, comparators, digital-to-analog converters and more. These allow for flexible signal sampling, feedback amplification and sensor monitoring. Together with the microcontroller, these solutions facilitate a myriad of compact applications with integrated power management, driving, feedback and control capabilities for DC power supplies up to 600V. 

Addressing safety with firmware

Qorvo's existing family of PAC5xxx integrates safety through firmware with protection against over-current, over-voltage, under-voltage and over-temperature conditions. The SoCs are equipped with a temperature sensor that can be accessed via an ADC channel on the (CAFE) with the parameters set and measured through the firmware.

Two levels of temperature protection are in play, including Temperature Warning and Temperature Fault, with the former declaring an over-temperature warning when the die temperature reaches 140°C and the latter generating an over-temperature fault when the die temperature reaches 1700C.

Qorvo’s next-generation intelligent BLDC controllers

Like all technologies, battery-powered tools continue to evolve to take advantage of the latest innovations, with new motor revisions and increased voltages. The same is true for BLDC and PMSM controllers, where many of the latest advances come in the form of new features for Class-B safety-critical applications, where failure can result in serious bodily harm. These include power tools such as chainsaws, cordless drills, angle grinders and more.

Qorvo, too, has evolved its intelligent motor controllers to reflect those advancements with its new PAC52xxx/55xxx platforms that simplify rugged system designs with integrated advanced protection for systems operating in the 44V-to-72V range. These retain the company's highly integrated approach that packs a programmable motor controller and driver on the same chip but goes beyond the feature set of the original PAC5xxx SoCs. These new controllers include hardwired safety features integrated within the SoCs themselves, rather than implemented in firmware.

Qorvo's new PAC52xxx/55xxx series of motor controllers can be used for a myriad of applications where precision, efficiency and safety are concerns for systems operating at voltages that range from 44V to 72V. These requirements are ideal for battery-powered power tools that require robust motor controllers capable of handling the rigors of construction sites, including power drills, saws and even inspection and mapping drones. They provide the flexibility needed for lawn and garden maintenance with the latest electric mowers, trimmers and leaf blowers. 

VDS sensing

The new controllers come equipped with VDS sensing for fast overcurrent and short circuit protection, which features a separate comparator and level shifter for high-side MOSFETs. It also provides programmable DAC-level references and programmable blanking intervals for each MOSFET, which allows designers to use smaller dies and lower-cost electronics due to the tighter control of current within the SOA. This improves reliability and protects the MOSFETs during unexpected current transients.

CBC protection

The new family of controllers is also equipped with cycle-by-cycle protection that ensures the controller acts quickly to any adverse conditions or faults that occur within the cycle of operation. This allows designers to maintain the safety and integrity of the motor and controller and significantly reduces power losses. It can also help reduce BOM costs, reduce processor overhead, and help minimize the complexity of the overall design.

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Figure 2: Cycle-by-cycle protection in the PAC52xxx series


Driver Disable and Brake functions

The motor control products provide additional safety features with Gate Driver Control options that allow designers the ability to deactivate or turn off the driver circuitry powering the motor should problems arise. The controllers are outfitted with an AIO2 pin to disable gate drivers (nDVRDIS) and a dedicated AIO4 pin to force the gate drivers to brake (nBRAKE) the motor should problems occur. The controllers are equipped with additional ADC inputs, including AIO3 and AIO5 pins with dedicated buffer feeding that's single-ended with programmable gain, which further helps to reduce BOM costs.


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Figure 3: Gate Driver Control


Qorvo's new family of motor controllers can also benefit applications outside the scope of power tools, including in the latest E-bikes where power efficiency is paramount, in warehouses where autonomous robots track inventory and in manufacturing where automated systems are the backbone of production. Home appliances, robotics, HVAC systems, medical equipment, autonomous vehicles and CNC machining are just a few of the applications that can benefit from Qorvo's next-gen PAC family of intelligent motor controllers, and that future looks bright.