Open-Source Reference Board Accelerates Rapid Development of Medical Ventilators

Many medical devices require precise embedded motion control at low speeds; during the COVID‑19 pandemic, ventilators became essential for patient care.

To accelerate ventilator design, Trinamic Motion Control (a Maxim Integrated subsidiary) unveiled an open‑source reference board as part of its Trinamic Open‑Source Ventilator (TOSV) initiative. The TMC4671+TMC6100‑TOSV‑REF board merges the TMC4671 servo controller and TMC6100 BLDC driver into a compact module. It supports 12‑36 V operation and up to 6 A RMS, meeting the power needs of medical ventilators and respiratory systems.

The board incorporates an SBC connector in the style of a Raspberry Pi and space for a pressure‑sensor add‑on, accelerating design cycles.

Ventilators must monitor pressure, flow, volume, and respiration rate. The reference design includes a Hall‑sensor interface and connectors for optional pressure‑sensor add‑ons. Real‑time data can be visualized on a Raspberry Pi equipped with a touchscreen using Trinamic’s free, open‑source firmware.

Trinamic’s goal is to demonstrate that ventilators can be built from readily available components, sidestepping supply‑chain delays during the pandemic. The company clarifies that it does not manufacture ventilators itself but provides a high‑quality foundation for medical‑equipment manufacturers to mass‑produce devices quickly.

Founder Michael Randt explained: “From the outset, we chose a high‑RPM turbine motor based on a BLDC design. Coupled with pressure and volume‑flow sensors, the dynamically controlled motor enables both pressure‑controlled and flow‑controlled ventilation modes.”

Leveraging prior experience with CPAP turbine control, Trinamic identified the challenges of fast, dynamic control of low‑induction BLDC motors. Balancing high switching frequency against current ripple, and the resulting switching and stator losses, is critical. The embedded TMC4671 servo controller generates a 100 kHz PWM and current‑control clock independent of the microcontroller. This reduces system current consumption by up to 15 % compared to a 25 kHz frequency, with no performance loss.

An add‑on board for I²C and analog sensors supports pressure sensors from multiple manufacturers. The TMC4671+TMC6100‑TOSV‑REF can be plugged into a single‑board computer to access the user interface and high‑level control functions; in the TOSV project, a Raspberry Pi with a touchscreen display was used.

The fully open‑source reference board, released mid‑July, includes hardware schematics, firmware, and software, all licensed under the MIT license.