Digital Signal Controllers Zero in on AI Data Center Power Supplies

Microchip Technology introduced a digital signal controller (DSC) with precision real-time control, a rich set of analog peripherals, and advanced cryptography suited for AI data center power and motor-control systems.

The dsPIC33AK256MPS306 is based on a 200-MHz, 32-bit core with a double-precision floating-point unit (FPU). Placed around it are high-resolution pulse-width modulators (PWM) with less than 100-ps timing and 12-bit analog-to-digital converters (ADCs) sampling up to 40 MSPS and oversampling to reach up to 16-bit resolution.

The chips also come with 5-ns high-speed comparators and digital-to-analog converters (DACs) with slope compensation. Such integration reduces the bill of materials (BOM) and simplifies placement on increasingly dense power boards.

These features help enable fast, deterministic control loops, particularly in AC-DC and DC-DC converters, including those based on silicon-carbide (SiC) and gallium-nitride (GaN) power devices running at fast switching speeds. These systems rely on digital power control, which is a method of managing power electronics using real-time MCUs instead of traditional analog circuits.

By enabling software-based regulation of voltage and current, digital power control can be employed to monitor and adapt to varying load conditions, resulting in higher efficiency. Shifting control into the software also gives engineers a lot more design flexibility.

The Power of Digital Power Control

The power-electronics industry is currently moving from analog to digital control, particularly in high-performance power-supply designs. Digital controllers are now deployed in most AC-DC and DC-DC power supplies in server racks.

 In a digitally controlled power supply, the voltage, current, and other output signals from the power supply are sampled and converted to a digital signal through the ADC inside (or outside) the MCU. The output signal is subsequently compared against reference values to generate an error signal, and then the MCU uses power-control algorithms to determine the necessary response. A digital compensator translates the error signal into PWM signals to drive the power stage.

The flexibility and efficiency of digital control is becoming a big deal in data centers, where power demands continue to escalate due to the AI boom. These new demands are driving power-per-rack specifications as high as 120 kW, with rack power densities projected to jump up to 500 kW — and potentially 1,000 kW — by 2030 while staying within the same form factor. To cram more power into these increasingly hot, overcrowded server racks, engineers are turning to the faster switching frequencies made possible by SiC and GaN.

These higher switching frequencies, which are in the range of 500 kHz to 1 MHz or above, help save space by shrinking capacitors, inductors, and other passives on the board. But they consequently also mean a shorter time to close the loop and execute the code in power-control algorithms.

Microchip, Infineon, Texas Instruments, and others are rolling out real-time digital controllers to keep up with the faster switching frequencies of SiC and GaN. For that, Microchip is incorporating very fast cores and peripherals into its dsPIC33A DSC family to ensure rapid, accurate power control under dynamic operating conditions. The broader family features high-performance ADCs and high-resolution PWMs that together reduce delays between the power supply and the digital controller, which is key to maintaining efficiency.

Digital Power for Brushless DC Motors

These same capabilities can apply to power conversion as well as complex motor control. Microchip said the dsPIC33AK256MPS306 can be used to control three-phase brushless DC (BLDC) motors with high accuracy and bandwidth, like those in cooling fans or liquid-cooling pumps in data centers or EVs.

The dsPIC33A core architecture also comes with fast 20-ns trigonometric sine and cosine function execution, supporting high-speed position control and field-oriented control (FOC) algorithms widely used in BLDC motors.

As with digital power, tighter integration is also important. Combined with a high level of analog integration, the new devices help enable high‑resolution, accurate, real‑time control-loop closure, which helps boost the performance of motor-control algorithms.

To stay ahead of increasing security requirements, the chips come with hardware security features for implementing secure boot, secure firmware updates, and secure debug. They feature hardware accelerators for cryptographic functions required by Open Compute Project (OCP)-aligned power supplies and other real‑time control systems. Moreover, the DSCs can accommodate the latest post-quantum cryptographic (PQC) algorithms. On top of that, the devices enable uninterrupted full‑cycle firmware updates crucial in today's server designs.

Digital controllers frequently have interfaces for monitoring and reporting voltage, current, temperature, and other system parameters to the host. These DSCs feature I3C connectivity, which is critical for real-time, low-latency telemetry on auxiliary power rails in data center racks and intelligent sensor networks in industrial automation. They have additional communication interfaces, including CAN FD, LIN, SPI, and I2C.

The digital controllers are designed to meet automotive (ISO 26262) and industrial (IEC 61508) functional-safety standards. Microchip said the devices will also be automotive qualified for operation at up to 150°C.