Microchip Technology QT100A-ISMG

Overview

QT100A-ISMG from QRG Ltd. is a single-key digital charge-transfer touch sensor IC designed for human interface replacement of mechanical switches. It operates from 2.0V to 5.5V, draws only 6.5µA at 2.0V (LP mode), features active-high digital output, and supports electrode overlays up to 50mm thick glass via patented spread-spectrum QTouch™ technology. It is used in lighting controls, consumer appliance panels, and interactive toys.

For engineers reviewing the QT100A-ISMG datasheet, QT100A-ISMG pinout, QT100A-ISMG application, or QT100A-ISMG equivalent, key selection considerations include its dual-package availability (6-pin WSON and 10-pin MSOP), self-calibrating burst-mode operation, 4-sample consensus detection filter, programmable sensitivity via Cs capacitor, and HeartBeat™ health-monitoring output pulse.

Technical Context

The QT100A-ISMG implements a burst-mode charge-transfer sensing architecture with spread-spectrum oscillator modulation (±7.5%) to reduce EMI emissions and improve noise immunity. Its internal signal processing includes asymmetric drift compensation, fixed 13-count threshold with 3-count hysteresis, and a 4-sample consensus filter that requires four consecutive detections before asserting the active-high output.

It supports three run modes-Fast (1ms burst interval), Low Power (~85ms sleep between bursts), and external Sync mode-controlled solely by the logic level or edge timing on the SYNC pin. The device performs full recalibration after ~80s Max On-duration timeout or power-up, with no dedicated recalibration pin required.

Key Specifications

Pinout & Package

QT100A-ISMG is supplied in a RoHS-compliant 10-pin MSOP package (MSL1, 260°C peak reflow). The package has a 3.0mm × 3.0mm body, 0.5mm pitch, and exposed thermal pad (not electrically connected).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar touch sensor applications.

Compared with QT100A-ISMG, QT100A-ISG offers identical sensing performance in a thinner, space-saving WSON package but demands careful PCB pad design to avoid shorts, while AT42QT1011-MAHR delivers lower quiescent current and smaller size at the cost of reduced EMI resilience and absence of diagnostic output pulses.

Availability

QT100A-ISMG is available at Aetrix Electronics and suitable for lighting controls, consumer appliance interfaces, and industrial HMI panels requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for QT100A-ISMG includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

QRG Ltd. is a UK-based semiconductor company specializing in capacitive touch sensing technology, founded to commercialize patented QTouch™ charge-transfer methods.

The QT100A product line delivers self-contained, single-key touch sensors optimized for mechanical switch replacement in cost-sensitive, low-power human interface applications across consumer, industrial, and interactive product categories.

FAQ

What is the primary function of the QT100A-ISMG in a touch interface design?

The QT100A-ISMG serves as a complete, self-contained single-key touch sensor IC that replaces mechanical buttons using patented charge-transfer technology. It acquires touch or proximity signals through dielectric overlays, performs all internal signal processing-including self-calibration, noise filtering, and consensus-based detection-and delivers a clean active-high digital output. Unlike microcontroller-based solutions, QT100A-ISMG requires no firmware, external ADC, or timing-critical code, making it ideal for rapid integration into lighting controls, appliances, and toys where reliability and low BOM cost are critical.

How does the SYNC pin affect QT100A-ISMG operation, and what are the valid configurations?

The SYNC pin on QT100A-ISMG determines run mode: held high enables Fast mode (~1ms burst interval), held low activates Low Power mode (~85ms sleep between bursts), and driven with falling-edge pulses enables Sync mode for multi-device coordination or 50/60Hz noise rejection. In Sync mode, the device wakes only on falling edges of the SYNC signal, eliminating cross-talk between adjacent sensors. QT100A-ISMG does not require external clock circuitry-the SYNC pin is purely a control input with CMOS-level thresholds (VIL = 0.8V, VHL = 2.2V at 3V).

Can QT100A-ISMG operate reliably behind thick or conductive panel materials?

Yes, QT100A-ISMG supports overlays up to 50mm thick glass or 20mm plastic by adjusting the external Cs capacitor (2nF–50nF) and electrode geometry. Its charge-transfer method projects fields through non-conductive dielectrics including stone, ceramic, wood, and painted surfaces-even low-density metallic paints. Conductive overlays (e.g., thin metal mesh) are not supported; however, small metal objects (e.g., knobs, handles) can become intrinsic sensors. Performance depends on Cs value, electrode size, and strict adherence to Cs ≫ Cx (stray capacitance <50pF) to maintain gain and stability.

What is the purpose and implementation of the HeartBeat™ pulse on the QT100A-ISMG OUT pin?

The HeartBeat™ pulse is a 15µs three-state output pulse generated once before every measurement burst on the QT100A-ISMG OUT pin, indicating real-time operational health. It appears as a brief high-impedance state that creates a positive-going edge when pulled up externally-enabling simple monitoring with a counter, microcontroller GPIO, or one-shot circuit. The pulse is visible only when no touch is detected; during active output, it is suppressed. No additional components are required to utilize it, and it does not interfere with relay or LED loads due to its low duty cycle.

How does QT100A-ISMG handle environmental drift and false triggers in varying conditions?

QT100A-ISMG employs asymmetric drift compensation that tracks slow signal changes only during non-detection periods, with faster recovery from decreasing signals (e.g., finger removal) than increasing ones (e.g., finger approach) to avoid premature nullification of valid touches. Combined with a 4-sample consensus filter requiring consecutive detections and ±7.5% spread-spectrum burst modulation, it rejects impulse noise, ESD events, and 50/60Hz interference. The fixed 13-count threshold and 3-count hysteresis further prevent oscillation near detection boundaries-ensuring stable operation across temperature, humidity, and supply voltage shifts without recalibration hardware.