AD7843ARQ-REEL7

Overview

The AD7843ARQ-REEL7 is a 12-bit successive approximation analog-to-digital converter (ADC) designed for touch screen digitizer applications. It operates from a single 2.2 V to 5.25 V supply and supports throughput rates up to 125 kSPS with a maximum power consumption of 1.37 mW at full speed. The device features a synchronous serial interface, programmable 8-bit or 12-bit resolution, and two auxiliary analog inputs. Integrated low on-resistance switches facilitate direct connection to resistive touch screens, while ratiometric conversion mode eliminates errors caused by switch resistance. A shutdown mode reduces current draw to less than 1 µA.

Feature Summary

• 12-bit SAR ADC with 125 kSPS throughput rate
• Integrated 4-wire touch screen interface with low on-resistance switches
• Programmable resolution: 8-bit or 12-bit via control register
• Ratiometric conversion mode for accurate touch position sensing
• Shutdown mode with <1 µA maximum current consumption

Applications

• Personal digital assistants (PDAs)
• Smart hand-held devices
• Touch screen monitors
• Point-of-sales terminals
• Pagers

Procurement Notes

Verify the package type matches the 'Q' suffix, indicating a 16-lead QSOP. Confirm the 'REEL7' suffix corresponds to the specific tape and reel quantity defined in the manufacturer's ordering guide. Ensure the temperature grade 'A' (-40°C to +85°C) meets system requirements. Cross-reference the datasheet revision B specifications for electrical parameters.

Selection Notes

Select this component when a high-speed, low-power ADC with integrated touch screen drivers is required. The ratiometric mode is essential for minimizing errors in resistive touch panels. Ensure the external reference voltage is between 1 V and VCC. Verify that the serial interface timing constraints (DCLK frequency up to 2 MHz) are compatible with the host microcontroller.

Part Context

The AD7843 is part of Analog Devices' family of touch screen controllers. The ARQ variant specifically denotes the industrial temperature range and QSOP packaging. The REEL7 designation indicates it is supplied in a standard tape-and-reel format suitable for automated surface-mount assembly processes.

Replacement Considerations

Publicly confirmed substitute part numbers are not available in the provided documentation. Users should consult the manufacturer's official replacement guide or contact technical support for qualified alternatives.