AR1021T-I/SS

Overview

The AR1021T-I/SS is a resistive touch screen controller from Microchip Technology's mTouch series, housed in a 20-SSOP package. It supports 4-wire, 5-wire, and 8-wire analog resistive sensors with a maximum 10-bit resolution. The device operates on a 2.5V to 5.0V supply and features I2C and SPI slave interfaces. Key specifications include a typical operating current of 17 mA during touch detection and a coordinate report rate of up to 140 reports per second. It includes an internal voltage reference, built-in drift compensation, and 128 bytes of user EEPROM for calibration storage.

Feature Summary

• Supports 4-wire, 5-wire, and 8-wire analog resistive touch sensors
• Features I2C (up to 400 kHz) and SPI slave communication interfaces
• Includes 128 bytes of user-accessible EEPROM for calibration data
• Operates within an industrial temperature range of -40°C to +125°C

Applications

• Mobile communication devices
• Personal Digital Assistants (PDA)
• Global Positioning Systems (GPS)
• Point of Sale Terminals
• Portable Instruments

Procurement Notes

Verify the specific ordering suffix 'I/SS' corresponds to the industrial temperature grade (-40°C to +125°C) and the 20-SSOP package type. Confirm interface requirements, as this part number specifies I2C and SPI capabilities distinct from UART-only variants. Ensure ESD protection components selected for the design do not introduce excessive capacitance that could degrade touch performance.

Selection Notes

Select the AR1021T-I/SS when designing systems requiring I2C or SPI connectivity for resistive touch screens. The M1 pin must be configured to VSS to enable I2C mode. For 5-wire sensor applications, the M2 pin requires connection to VDD, whereas 4/8-wire sensors require M2 connected to VSS. Verify that the host system can handle the open-drain nature of the SCL and SDA lines with appropriate pull-up resistors.

Part Context

This component belongs to the AR1000 Series, which provides universal resistive touch screen control. The AR1021 variant specifically distinguishes itself from the AR1011 by offering digital serial interfaces (I2C/SPI) instead of UART. The 'T' indicates tape and reel packaging, while 'I' denotes the industrial temperature rating. The SS suffix identifies the 20-pin Shrink Small Outline Package.

Replacement Considerations

Publicly confirmed substitute part numbers are not available in the provided documentation. Designers should consult Microchip for direct replacements or cross-references based on specific interface and package constraints.