Touch Controllers Handle Large Screens And Buttons

Atmel’s maXTouch mXT106xT2 handles multitouch chores for screens from 1.5-in to 15.6-in. It also has integrated capacitive button support (Fig. 1). This integration allows a single chip to handle input support for tablets and smartphones eliminating additional external components from the bill-of-materials. It will easily handle multitouch chores for Windows 8 and Android devices.

The chips use mutual and self capacitance and they can also handle moisture and glove support not found in many multitouch controllers. They can handle a passive stylus with 256 pressure levels and a tip size of only 1-mm. This is at a 120 Hz scan rate providing fast feedback via the on-chip, 32-bit microcontroller.

The mXT1068T2 adds support for 1-mm active stylus support and it has a 25-mm detect range allowing it to provide hover detection up to 20-mm.

The chip’s 12-channel, peripheral touch controller (PTC) handles up to a dozen capacitive touch buttons without using up the X/Y lines used for the multitouch screen support. This is typically done with an additional chip or having the microcontroller use I/O interfaces that are not specially designed for touch support. Atmel’s solution has an integrated hardware oversampling and an improved front-end and integrator to improve noise immunity.

The chips are available with 114-ball HDI (high density interconnect) UFBGA (7- by 5- by 0.6-mm) with a 0.5-mm pitch or a non-HDI 117-ball UFBGA (9.5- by 7- by 0.65-mm) with a 0.65mm pitch. There is also an on-chip voltage tripler that delivers up to 9.9 V with no external regulators required.