QT60040-IS-TR

Overview

The QT60040-IS is a CMOS charge-transfer sensor IC designed for matrix touch controls, operating within an industrial temperature range of -40°C to +85°C. It detects up to four keys using a 4x1 matrix configuration with four X drive lines and one Y receive line. The device features four active-high outputs capable of sensing up to two simultaneous key presses. It operates on a single power supply ranging from 2.5V to 5.5V with typical supply currents of 0.6mA at 3V and 0.65mA at 5V. A single external sampling capacitor (Cs) between 22nF and 220nF is required for operation.

Feature Summary

• Transverse charge-transfer technology enables detection through various dielectric materials without requiring custom molded membranes.
• Integrated self-calibration and asymmetric drift compensation algorithms ensure stable sensing under changing environmental conditions.
• Configurable Max On-Duration feature allows automatic recalibration after 10 or 60 seconds of continuous detection to handle foreign objects.
• Simple direct active-high drive outputs provide logic-level switching signals for each sensing channel.

Applications

• Automotive controls
• PC and peripheral controls
• ATM machines
• Appliance controls
• Industrial keyboards

Procurement Notes

Verify the specific suffix 'IS' confirms the -40°C to +85°C industrial temperature rating and SOIC-14 package. Confirm that the ordering information matches the manufacturer's current datasheet revision, as specifications are subject to change without notice. Ensure compatibility with the required external components, specifically the Cs capacitor type and value, before finalizing procurement.

Selection Notes

Select this component when a low-cost, robust solution for up to four touch keys is required. The 4x1 matrix architecture minimizes interconnect requirements compared to per-key solutions. Consider the option pins for configuring rollover behavior and recalibration timeouts based on application needs. Ensure the panel material thickness does not exceed 6mm for optimal performance.

Part Context

The QT60040 utilizes Quantum Research Group's patented transverse charge-transfer technology. It is part of a family of QMatrix ICs designed for domestic appliances, computer peripherals, and security panels. The device eliminates the need for exotic fabrication techniques like chip-on-glass, allowing the use of standard PCB or flex circuit materials for electrode implementation.

Replacement Considerations

Publicly confirmed substitute part numbers are not available in the provided documentation. Verify if other members of the QT60040 series, such as the DIP variant, meet the specific package or temperature requirements of the design.

FAQ

How does the QT60040 handle simultaneous key presses?

The device can sense any two keys simultaneously by default. This functionality can be restricted to only one key at a time by connecting the OPT1 pin to ground.

What is the purpose of the external Cs capacitor?

The Cs capacitor is a shared sampling capacitor used to accumulate charge during the burst cycle. Its value, typically between 22nF and 220nF, determines the sensitivity and burst length of the sensor.

How does the device manage signal drift over time?

The QT60040 employs an asymmetric drift compensation algorithm where the reference level tracks the raw signal slowly. It compensates faster for decreasing loads to allow quick recovery and slower for increasing loads to maintain sensitivity to approaching fingers.