Touch-screen controllers feature ESD protection

A Maxim Integrated Products product story

Edited by the Electronicstalk editorial team Aug 28, 2002

The MAX1233 and MAX1234 are programmable four-wire touch-screen controllers.

The MAX1233 and MAX1234 are programmable four-wire touch-screen controllers, which include a keypad interface that can also be used as eight pins of GPIO, voltage reference, internal clock, and an 8bit DAC output for LCD contrast control.

These parts contain a low-power, 12bit sampling ADC with low-on-resistance switches for driving resistive touch screens, making them ideal for battery-operated systems, such as PDAs and other portable equipment.

The MAX1233/MAX1234 offer two battery-measurement inputs capable of reading battery voltages up to 6V regardless of supply voltage, two auxiliary analogue inputs, the control to measure touch pressure, an on-chip temperature sensor capable of reading 0.3C resolution, and ESD protection of up to 8kV contact discharge method and +/-15kV air-gap discharge method per IEC1000-4-2 on all analogue input pins.

These devices interface to the host controller through a standard SPI/QSPI/Microwire-compatible serial interface.

They offer programmable resolution from 8 to 12bit and sampling rates up to 50kHz.

Guaranteed to operate with a supply voltage from 2.7 to 3.6V (MAX1233) and from 4.75 to 5.25V (MAX1234), they consume only 50uA at 10Ksample/s throughput and under 0.3uA in shutdown mode.

The MAX1233/MAX1234 are capable of making fully differential position measurements from the touch screen, eliminating the errors resulting from routing and switch resistance.

In addition, the internal software-selectable 2.5 or 1.0V reference can be disabled, allowing the use of an external reference from 1.0V to V(DD).

The MAX1233/MAX1234 are offered in 5 x 5mm 28-pin QFN packages and are guaranteed over the -40 to +85C temperature range.

Prices start at $2.50 (1000-up, FOB USA).