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TacTouch haptic actuator controller integrates touch-pressure measurement for piezo and polymer actuators

12th August 2010

Maxim Integrated

ES Admin

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Maxim introduced the MAX11836, a TacTouch haptic actuator controller for single-/multilayer piezo actuators and electroactive polymers (EAPs) in touch-enabled devices. Building on the success of the Company's MAX11835, the MAX11836 adds drive/sense circuitry for connecting up to four external force-sense resistors (FSRs) to measure touch pressure. Using FSRs with a capacitive touch-screen controller (C-TSC) helps avoid false touches and saves system power, as the C-TSC can remain in a power-down state during system idle times and wake up only when a touch is detected. A single-chip solution, the MAX11836 simplifies adding haptic feedback to any end application with a touch screen or touch buttons. Targeted devices include cell phones, portable media players, digital photo frames, multifunction printers, digital still/video cameras, point-of-sale (POS) terminals, e-readers, tablet PCs, and notebooks.

The MAX11836 features built-in storage of user-defined haptic patterns, playout logic, output-configurable DC-DC conversion, and output drivers for highly capacitive loads. This integration enables the device to drive a wide range of haptic actuators, such as single- or multilayer piezo actuators. The device's internal boost converter supports actuators from 10V to 250V.

While other solutions require the host processor to store the haptic waveforms and perform playout in real time to a discrete DC-DC conversion/driver circuit, the MAX11836 only requires a low-voltage supply and a serial I2C interface to the host processor. The host processor downloads user-defined haptic patterns at power-up through the serial interface. During operation, playout from on-chip memory is triggered in one of three ways: through a serial interface command, through the built-in touch-detect function, or through a proprietary single-wire link (MAX11835) that is compatible with other Maxim products. This single-wire interface determines the trigger instant and identifies which waveform from up to sixteen patterns can be simultaneously stored in on-chip memory. Compared to other solutions, the benefit of Maxim's haptic solutions is a near-zero-latency haptic output, as there is no delay added due to the operating system running on the host processor. This provides a natural touch feeling, even when the user is typing fast on a multitouch touch-screen keyboard.

The MAX11836 is packaged in an ultra-small, 1.6mm x 1.6mm, 25-bump wafer-level package (WLP) to support the miniaturization of end products. The MAX11836 is now in mass production, as is the MAX11835. Pricing for the MAX11836 starts at $1.65 (1000-up, FOB USA). Please contact the factory for ordering and sampling information.