Most piezo drivers charge the actuator, then dissipate that charge as heat once the actuation is done. CapDrive doesn't discharge to ground — it recovers the energy and reuses it on the next cycle.
It runs on a single power inductor acting as a bidirectional pump. Energy flows from the power source into the inductor, then into the actuator, then back out again instead of being switched away as heat. The same inductor handles both the buck and boost stages, so CapDrive can output anywhere from 0 to 120V, AC or DC, unipolar or bipolar, from that one component.
Because no energy is being burned off between cycles, CapDrive idles at microamp-level quiescent current, even while driving high-voltage waveforms.
Read the full technical breakdown, including the energy transfer equations, on our engineering blog: What Is CapDrive?
10x More Power Efficient.
CapDrive recovers energy from the actuator on every cycle instead of dissipating it as heat, the way legacy drivers do. That's what gets power consumption down by up to 90%, without giving up high-definition haptics in battery-constrained devices. See How CapDrive Works above for the mechanism.
4x Smaller PCB Footprint
Linear drivers need extra components to manage the heat from dissipated energy. Switching drivers need larger output filters to manage noise. CapDrive needs neither at the same scale. The energy recovery removes the heat problem, and the single-inductor design removes the filtering problem. That's what shrinks the footprint by 4x.
Integrated Force Sensing
CapDrive™ wakes from sleep and outputs its first waveform in 0.3ms. There's no ramp-up and no perceptible delay between input and haptic response.
LRAs need to spin up to their resonant frequency before you feel anything. That's where most of the delay comes from. CapDrive drives the piezo actuator directly, so voltage moves the material the instant power reaches it. No resonance to build, no waveform to wait for.
Legacy haptic motors create the foggy view on the left. They accelerate slowly and vibrate with a lack of focus that hides the details. This "muddy" feedback disconnects the user from the device.
To reveal the sharp definition on the right, you need piezo actuators driven by CapDrive™. Our technology delivers the precise high-voltage control required to stop and start the actuator instantly. This allows the piezo to render textures that are as crisp and distinct as a mountain peak in bright sunlight.
CapDriveTM Technology brings HD Haptic feedback and integrated force sensing to the smallest devices, while reducing the solution's power consumption.
| Features | LRA | Piezo - Competition | Piezo - CapDriveTM |
| Power Consumption | Medium | Medium | Low |
| Start-Up Time [ms] | 25 | 1.5 | 0.3 |
| Footprint Size | Big | Small | Miniature |
| Integrated Pressure Sensing | No | No | Yes |
| HD Haptics | No | Yes | Yes |
LRA = Linear Resonant Actuator, Piezo - Competition = TDK PowerHapTM 2.5G Piezoelectric actuator coupled with competitor's driver, Piezo - CapDriveTM = TDK PowerHapTM 2.5G Piezoelectric actuator coupled with Boréas CapDriveTM driver technology
*with 100g mass. Acceleration is related to feedback strength. Higher number = Stronger feedback
What's Actually Different
LRA motors run at a fixed vibration frequency, so the output stays diffuse no matter how good the drive electronics are. Linear piezo drivers dissipate energy in the linear stage on every cycle, so power consumption and heat scale directly with actuation frequency. Switching piezo drivers recover some of that energy, but the switching noise they introduce requires a larger output filter, which is what drives up their footprint.
CapDrive recovers energy through a single bidirectional inductor and outputs arbitrary waveforms up to 120V. No fixed frequency, no linear-stage loss, no oversized filter to work around.
Frequently asked questions
Is CapDrive a buck or a boost converter?
It is both — a buck and a boost converter with self-managed behavior. The controller switches between modes automatically, cycle by cycle, rather than being fixed as a step-up or step-down, which is how it tracks an arbitrary output efficiently.
What kind of loads can CapDrive work with?
Any capacitive loads such as piezo actuators, MEMS and capacitors, from the low-nanofarad range up to a couple of microfarads. Each Boréas IC specifies a recommended load impedance range for its target applications.
What output voltages and waveforms can CapDrive produce?
Boréas ICs can produce any arbitrary waveform up to 120 V, unipolar or bipolar, AC or DC, depending on the selected product.
When driving a load, smooth waveforms such as sine waves or Gaussians are recommended to minimize audible noise — see Boréas's app note on audible noise reduction.
How does CapDrive save energy?
It works as a bidirectional energy pump: rather than dumping the load's stored energy as heat, it recovers that energy back to the power rail. The power consumed is therefore only losses in the actuator load, and from the conversion process.
What are the main sources of power loss?
The main losses are due to the inductor's resistance (DCR) and magnetic core, the transistor channel, and gate-drive switching. All are small relative to the energy delivered.
What external components does CapDrive require?
Key external passives required are a power inductor, a sensing resistor and low-cost capacitors. Some products also require external FETs.
What sets the maximum output power?
The absolute maximal output power is set by each product based on design and target applications. Then, the BOM can be set to define a maximum power transfer suited to a specific application. This can be done using Boreas' BOM calculator to optimize the BOM and reduce the solution footprint.
