Boréas builds CapDrive piezo haptic driver ICs delivering up to 120 V unipolar or +95 V and -95 V bipolar, in single and multi channel versions, for consumer and automotive designs. Most of them drive the piezo actuator and sense force through that same actuator, so a solid state button needs no separate force sensing subsystem. This page compares the lineup so you can pick a part without opening four datasheets.
The highest output voltage in the lineup, in the smallest package, with force sensing built in. It runs directly from a single cell battery, starts an effect in under 300 µs, and drops to 0.5 µA when not used.
190 Vpk-pk bipolar / 3.0 to 5.5 V in / WLCSP 2.1 x 1.7 mm / 0.5 µA sleep
The same features as the BOS1921 without sensing, which brings the cost down. Use it when the design has its own external sensor, or when nothing needs to be sensed at all, such as driving a piezoelectric micropump.
190 Vpk-pk bipolar / 3.0 to 5.5 V in / WLCSP 2.1 x 1.7 mm / no sensing
Four independent output channels from one IC, each able to drive and sense on its own. Zero Power Sensing keeps force detection alive while the rest of the system sleeps, and effects can be synchronized across channels.
0 to 60 V / 4 channels / 4 GPIO / 220 µV sensing / 10 kSPS
BOS1211 AEC-Q100 G2
Runs from the car battery 12 V rail and drives the large, high capacitance actuators an automotive surface needs, with sensing included. The wettable flanks package lets solder joints be inspected optically.
0 to 120 V / 9.0 to 16 V in / 4 µF load / QFN-24 wettable flanks
| Parameter | BOS1921 | BOS1931 | BOS0614 | BOS1211 |
|---|---|---|---|---|
| Target application | Consumer | Consumer | Multi channel | Automotive |
| Output voltage | 190 Vpk-pk (+95 V / -95 V) |
190 Vpk-pk (+95 V / -95 V) |
0 to 60 V | 0 to 120 V |
| Output type | Bipolar | Bipolar | Unipolar | Unipolar |
| Integrated piezo sensing | Yes, 7 mV resolution | Not available | Yes, 220 µV resolution | Yes, 130 mV resolution |
| Supply voltage | 3.0 to 5.5 V | 3.0 to 5.5 V | 3.0 to 5.5 V | 9.0 to 16 V |
| I/O supply | 1.62 to 5.5 V | 1.62 to 5.5 V | 1.2 to 1.8 V | 1.62 to 5.5 V |
| Output channels | 1 | 1 | 4 | 1 |
| GPIO | 1 | 1 | 4 | 1 |
| Max capacitive load * | 820 nF | 820 nF | 875 nF total | 4 µF |
| Start-up time | Under 300 µs | Under 300 µs | Under 500 µs | Under 500 µs |
| Sleep current | 0.5 µA | 0.5 µA | 4 µA | 8 µA |
| THD+N | < 1% | < 1% | < 1% | < 1% |
| Digital interface | MIPI I3C/I2C | MIPI I3C/I2C | MIPI I3C/I2C | SPI |
| Waveform FIFO | 1024 samples | 1024 samples | 1024 samples | 1024 samples |
| Package | WLCSP 2.1 x 1.7 mm QFN 4 x 4 mm |
WLCSP 2.1 x 1.7 mm QFN 4 x 4 mm |
WLCSP 2.1 x 2.5 mm | QFN-24 wettable flanks |
| Qualification | Consumer | Consumer | Consumer | AEC-Q100 Grade 2 |
* Maximum capacitive load is indicative only. Higher loads can be used under relaxed operating conditions.
Every part uses the CapDrive architecture, a 1024 sample waveform FIFO and 2 kB of waveform RAM. Values are taken from the abridged datasheets linked below. Consult the full datasheet before committing a design.
Also in the family. The BOS1901 is the original CapDrive driver, superseded for new designs by the BOS1921. The BOS1221 is an automotive driver with a wider supply range, available on request rather than through general distribution. Contact us if your design needs it.
The actuator sets the voltage you need. A larger piezo element needs a higher electric field to deform enough to be felt, and the actuator you can use is set by the space, weight and power your product can give it. Choose the actuator for the application first, then pick the driver that reaches its rated voltage. Not sure which actuator type fits your product? Read Piezo vs LRA vs ERM: How to Choose a Haptic Actuator.
A bipolar driver produces waveforms with both positive and negative amplitude, a unipolar driver works only with positive voltage. A bipolar driver will run a unipolar actuator, but a unipolar driver cannot properly run a bipolar one. The BOS1921 and BOS1931 are bipolar at +95 V and -95 V. The BOS0614 and BOS1211 are unipolar, at 0 to 60 V and 0 to 120 V.
A piezo actuator behaves electrically like a capacitor, typically a few nF to a few µF for haptic actuators. That capacitance sets how much energy is needed to build the voltage across it, so the driver has to be rated for your actuator's capacitance. Under-rate it and the effect falls short of what the actuator can produce. Note a higher load can be used under relaxed operating conditions.
The piezoelectric effect is reversible, so the same actuator that produces the effect also generates a measurable voltage when it is pressed. A driver with integrated sensing reads that directly, which removes a separate force sensing subsystem from the bill of materials. For a solid state button that is usually the deciding factor. Where sensing is not needed, the BOS1931 delivers the same drive performance at lower cost.
Force sensing. The BOS1931 offers the same features as the BOS1921 without the sensing function, which brings the cost down. Drive performance is the same: both deliver 190 V peak to peak from a 3.0 to 5.5 V supply in the same package options. Choose the BOS1921 when the design senses force through the actuator, such as a solid state button. Choose the BOS1931 when the design uses an external sensor, or when nothing needs to be sensed at all, such as driving a piezoelectric micropump.
The BOS1921 and the BOS1931 both deliver 190 V peak to peak, which is +95 V and -95 V bipolar, from a 3.0 to 5.5 V supply. That is the largest output swing in the Boréas lineup, and it is available in a WLCSP measuring 2.1 x 1.7 mm. The BOS1211 reaches the highest single-ended voltage at 0 to 120 V.
The BOS1211 is qualified to AEC-Q100 Grade 2. It runs from a 9.0 to 16 V supply, delivers 0 to 120 V, drives up to 4 µF of capacitive load, and ships in a wettable flanks QFN-24 so solder joints can be inspected optically. It includes integrated piezo sensing.
A micropump needs drive but not sensing, so the BOS1931 is usually the right part: 190 V peak to peak of bipolar drive from a 3.0 to 5.5 V supply, with the sensing function removed to lower cost.
The BOS0614 has four output channels, so it drives and senses four actuators from a single IC. Multiple BOS1921 devices can also be used to play several waveforms synchronously, keeping the phase within 2 µs.
With the exception of the BOS1931, which has no sensing function, CapDrive based drivers read the voltage the actuator generates when it is pressed, through the same two wires that drive it. The BOS1921 resolves 7 mV and the BOS0614 resolves 220 µV, and the BOS0614 keeps sensing active in Zero Power Sensing while the rest of the system sleeps.
The consumer parts, the BOS1921, BOS1931 and BOS0614, run from 3.0 to 5.5 V, so they work directly from a single cell lithium battery or a 5 V rail. The automotive BOS1211 runs from the car battery 12 V rail, at 9.0 to 16 V.
CapDrive recovers the energy stored in the actuator's capacitance and reuses it rather than dissipating it as heat, which is what brings consumption to as little as a tenth of other piezo drivers on the market. Between effects, each driver can be set to sleep or sensing modes with reduced power consumption.
Abridged datasheets, no registration required.
