AR1021T-I/SO

Overview

The AR1021T-I/SO is a resistive touch screen controller from the Microchip mTouch AR1000 Series, housed in a 20-pin SOIC package. It supports 4-wire, 5-wire, and 8-wire analog resistive sensors with a maximum 10-bit resolution and a typical report rate of 140 reports per second. The device operates on a 2.5V to 5.0V supply, drawing 17 mA during touch activity. It features I2C slave communication (up to 400 kHz) with a fixed 7-bit address of 0x4D. Key specifications include built-in drift compensation, 128 bytes of user EEPROM for calibration storage, and an industrial temperature range of -40°C to +85°C.

Feature Summary

• Supports 4/5/8-wire analog resistive touch sensors with proprietary decoding algorithms.
• Includes 128 bytes of onboard user EEPROM for independent coordinate calibration storage.
• Features built-in drift compensation algorithm to maintain accuracy over time.
• Provides low-power sleep mode with standby current as low as 40 µA at 2.5V.

Applications

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

Procurement Notes

Verify that the M1 pin is connected to VSS to configure the device for I2C communication, as required by the AR1021 variant. Ensure the host system supports the specific 7-bit I2C address (0x4D). Confirm that the application schematic includes the necessary pull-up resistors on SCL and SDA lines and adheres to the ESD protection guidelines specified in the datasheet to prevent performance degradation.

Selection Notes

Select the AR1021T-I/SO when I2C interface compatibility is required, distinguishing it from the SPI-only AR1011 or UART-only variants. The 'I' suffix indicates the industrial temperature range (-40°C to +85°C), suitable for broader environmental conditions compared to commercial grades. The 'SO' suffix confirms the 20-pin Small Outline Integrated Circuit package, which must be matched against PCB footprint requirements versus SSOP or QFN alternatives.

Part Context

This component belongs to the Microchip mTouch AR1000 Series, designed to offload processing overhead from the host microcontroller. Unlike capacitive controllers, this series specifically targets analog resistive technologies. The AR1021 variant is distinct within the family due to its I2C interface capability, whereas other models may rely solely on SPI or UART protocols.

Replacement Considerations

The AR1021T-I/SS offers identical electrical and functional specifications but utilizes a 20-SSOP package instead of SOIC. For applications requiring a different interface, the AR1011 provides SPI support, while the base AR1021 model serves as the non-tape-and-reel equivalent.