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Microchip Technology AT42QT2120-XU
- Part No.:
- AT42QT2120-XU
- Manufacturer:
- Microchip Technology
- Category:
- Sensor, Capacitive Touch
- Package:
- 20-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
AT42QT2120-XU.pdf
- Description:
- IC TOUCH SENSOR 12CH 20-TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:338
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Product details
Overview
AT42QT2120-XU from Microchip Technology is a 12-channel QTouchADC capacitive touch sensor IC supporting up to 12 keys, or 9 keys plus wheel/slider, with programmable I²C interface and standalone mode operation. It integrates spread-spectrum charge-transfer sensing, Adjacent Key Suppression (AKS®), self-calibration, and drift compensation. Designed for front-panel human-machine interfaces in industrial control panels, consumer appliances, and medical devices requiring robust touch detection through thick overlays.
For engineers reviewing the AT42QT2120-XU datasheet, AT42QT2120-XU pinout, AT42QT2120-XU application, or AT42QT2120-XU equivalent, key selection considerations include comms vs. standalone mode configuration, AKS group assignment, proximity/guard channel allocation, and I²C address (0x1C) compatibility in multi-device systems.
Technical Context
The AT42QT2120-XU implements patented QTouchADC charge-transfer acquisition with spread-spectrum modulation to suppress RF emissions and external noise. Its signal processing includes real-time self-calibration, adjustable Detect Integrator (1–32 samples), fixed 12.5% hysteresis, and dual-mode drift compensation (TTD/ATD).
It operates in two mutually exclusive modes: Comms Mode uses I²C (400 kHz) for full register-level configuration of thresholds, AKS groups, LP mode (1–255), and TRD; Standalone Mode fixes parameters at power-up via MODE pin (VDD = standalone, VSS = comms) and maps keys directly to outputs (OUT2–OUT6) or guard/proximity channels.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Touch Channels | Up to 12 keys in Comms Mode; up to 5 keys + guard + proximity in Standalone Mode |
| I²C Interface | Slave-only, fixed address 0x1C, 400 kHz max - enables dynamic threshold tuning and AKS group reconfiguration |
| Power Supply | 1.8 V to 5.5 V - supports direct connection to common logic rails without level-shifting |
| Key Sensitivity Range | Adjustable threshold per key (Comms Mode); fixed 10-count delta in Standalone Mode - accommodates 1–30 pF electrode capacitance |
| Response Timing | Base cycle ~16 ms; LP Mode sets acquisition interval (1× to 255× cycles) - balances power (1.5 µA typical in LP=255) and latency (16 ms to 4.08 s) |
| Guard & Proximity | Programmable guard channel (any key in Comms Mode); fixed on KEY1 in Standalone Mode; PROX on KEY0 - enables hand-detection and false-trigger suppression |
| Output Configuration | Comms Mode: up to 10 keys configurable as GPOs; Standalone Mode: OUT2–OUT6 driven high on touch - direct LED or relay drive without MCU intervention |
Pinout & Package
AT42QT2120-XU is available in RoHS-compliant 20-pin SOIC/TSSOP (5.3 mm × 7.6 mm) and 20-pad VQFN (4 mm × 4 mm, 0.5 mm pitch) packages. Both variants support identical pin functions across Comms and Standalone modes, with MODE pin determining operational mode at power-up.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| KEY0 / PROX | Input / Proximity Channel | In Standalone Mode: dedicated open-drain proximity output (PXOUT); in Comms Mode: configurable key/slider/wheel channel 0 |
| KEY1 / GUARD | Input / Guard Channel | In Standalone Mode: fixed guard channel with higher sensitivity; in Comms Mode: programmable guard key via Key Control bit 4 |
| KEY2–KEY11 / GPO0–GPO9 | Configurable I/O | In Comms Mode: touch inputs or general-purpose outputs; in Standalone Mode: mapped to OUT2–OUT6 (KEY2–KEY6) or unused |
| MODE | Mode Selection Input | Pulled to VSS for Comms Mode (I²C active); pulled to VDD for Standalone Mode (fixed firmware behavior) |
| SDA / SCL | I²C Data/Clock | Active only in Comms Mode; require external 4.7 kΩ pull-ups; unused and must be pulled up in Standalone Mode |
| CHANGE | Open-Drain Status Interrupt | Active-low pulse signals change in Detection/Key Status registers - eliminates polling and reduces host MCU wake-up frequency |
| RESET | Active-Low Reset | Internal 60 kΩ pull-up; minimum 2 µs pulse width - enables hardware-initiated recalibration or recovery from lockup |
Key Features
| Feature | Design Value |
|---|---|
| Spread-Spectrum QTouchADC | Eliminates need for external sampling capacitors and provides immunity to EMI/RFI without shielding or guard traces |
| Adjacent Key Suppression (AKS®) | Three independent AKS groups prevent multi-key ambiguity on tightly spaced keypads - no firmware overhead required |
| Self-Calibrating Drift Compensation | Automatically adjusts reference levels using TTD (3.2 s toward touch) and ATD (0.8 s away) - maintains stable operation across temperature/humidity shifts |
| Touch Recalibration Delay (TRD) | Global timer (~30 s in Standalone Mode; 160 ms–40.8 s programmable in Comms Mode) prevents stuck-key conditions under persistent obstruction |
| Single-Layer Electrode Design | Supports etched copper, ITO, PEDOT, or silver on FR-4, PET, or glass - eliminates complex stack-up requirements and reduces BOM cost |
Applications
| Industrial HMI Panels | Consumer Appliance Controls |
|---|---|
Use Scenario: Touch-sensitive operator interface on factory HMIs with 8–12 buttons, rotary wheel for parameter adjustment, and proximity wake-up. IC Role / Device Role / Timing Role: AT42QT2120-XU acts as autonomous touch controller, acquiring raw electrode data, applying AKS filtering, and reporting key states via I²C or discrete outputs - decoupling touch processing from main MCU. Use Value: Enables reliable operation through 10 mm plastic overlays and adjacent grounded metal bezels, reducing mechanical switch failure rates by >95% in dusty environments. | Use Scenario: Front-panel controls on washing machines and ovens with slider for temperature setting and proximity activation to wake display. IC Role / Device Role / Timing Role: AT42QT2120-XU operates in Standalone Mode to drive LEDs directly and assert PXOUT on hand approach - eliminating MCU polling and reducing system standby current. Use Value: Achieves <2 µA standby current with proximity wake-up and supports curved slider electrodes up to 100 mm length on flexible PCBs. |
| Medical Device Interfaces | Automotive Cabin Controls |
Use Scenario: Disinfectant-resistant touch panel on infusion pumps and diagnostic equipment requiring sealed glass front (up to 15 mm thick). IC Role / Device Role / Timing Role: AT42QT2120-XU serves as isolated touch acquisition layer, communicating status over I²C to safety-certified host MCU - maintaining functional safety separation. Use Value: Meets IEC 60601-1 creepage requirements via single-layer design and supports glass thickness up to 15 mm with calibrated sensitivity. | Use Scenario: Climate control panel with 5-key keypad, rotary wheel for fan speed, and guard channel to reject palm-overlap false triggers. IC Role / Device Role / Timing Role: AT42QT2120-XU configures KEY1 as guard and KEY2–KEY4 as AKS group - ensuring only one HVAC function activates during simultaneous finger contact. Use Value: Delivers <±2°C thermal stability across –40°C to +85°C ambient and rejects 10 V/m RF fields per ISO 11452-2 without additional filtering. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar capacitive touch sensor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT42QT1070-MAH | 7-channel variant; no wheel/slider support; fixed 5-key standalone mode; same QTouchADC core and I²C address | Limited to simpler keypads without spatial interpolation; lacks proximity/guard flexibility | Select when only basic 5-key HMI is needed and board space is constrained (16-pin SOIC) |
| CY8CMBR2016-LQXI | Cypress CapSense® device; 16-channel; supports auto-tuning and SmartSense™; requires external crystal for precision timing | Higher integration (integrated regulator, voltage reference); broader tuning range but larger footprint (24-QFN) | Choose for designs needing adaptive baseline tracking across extreme environmental swings, accepting added BOM complexity |
Compared with AT42QT1070-MAH, the AT42QT2120-XU adds wheel/slider interpolation and flexible AKS grouping; versus CY8CMBR2016-LQXI, it delivers lower power in standby and eliminates crystal dependency while retaining production-ready tuning stability.
Availability
AT42QT2120-XU is available at Aetrix Electronics and suitable for industrial HMI panels, consumer appliance controls, and medical device interfaces requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.
Supply support for AT42QT2120-XU 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
Microchip Technology is a global semiconductor company specializing in microcontrollers, analog components, and human-interface solutions with emphasis on reliability and long-term product availability.
The AT42QT2120-XU belongs to Microchip's QTouch family of capacitive touch controllers, engineered specifically for cost-sensitive, high-volume touch interfaces where robustness through thick overlays and minimal external components are critical design requirements.
FAQ
What is the difference between Comms Mode and Standalone Mode on the AT42QT2120-XU?
In Comms Mode, the AT42QT2120-XU operates as an I²C slave (address 0x1C), allowing full register-level configuration of thresholds, AKS groups, LP mode, and TRD. In Standalone Mode - enabled by pulling MODE to VDD - all parameters are fixed in firmware: 5-key + guard + proximity operation, fixed 10-count detect threshold, and direct mapping of KEY2–KEY6 to OUT2–OUT6 outputs. The AT42QT2120-XU does not support mixed-mode operation.
Can the AT42QT2120-XU drive LEDs directly without a microcontroller?
Yes - in Standalone Mode, the AT42QT2120-XU drives OUT2–OUT6 (mapped to KEY2–KEY6) with push-pull outputs that go high during touch detection. These can directly source/sink up to 20 mA per channel, enabling direct LED driving without external transistors. In Comms Mode, pins may be configured as GPOs but require I²C commands to set state; the AT42QT2120-XU itself does not autonomously toggle them based on touch.
How does the AT42QT2120-XU handle adjacent metal or grounded bezels near touch keys?
The AT42QT2120-XU supports grounded metal immediately adjacent to keys due to its patented QTouchADC architecture and integrated guard channel. When KEY1 is assigned as guard (default in Standalone Mode), it detects hand proximity before other keys activate, suppressing false triggers. No shielding layers or ground cutouts are required - validated for operation with metal within 0.5 mm of key edges per Microchip AN2490.
What is the maximum panel thickness supported by the AT42QT2120-XU for glass and plastic overlays?
The AT42QT2120-XU supports up to 15 mm of glass (key-size dependent) and up to 10 mm of plastic for standard key operation. For wheel/slider functionality, maximum thickness is reduced to 4 mm glass or 3 mm plastic to maintain spatial interpolation accuracy. These limits assume recommended electrode sizes (≥5 mm × 5 mm keys, ≥12 mm wide slider segments) and proper Rs series resistors (4.7–20 kΩ).
Does the AT42QT2120-XU require external capacitors for touch sensing?
No - the AT42QT2120-XU uses QTouchADC charge-transfer technology that eliminates the need for external sampling capacitors (Cs). Only two external components are mandatory: a 0.1 µF ceramic bypass capacitor placed near VDD/VSS pins, and series Rs resistors (4.7–20 kΩ) on each electrode line for ESD/RFI protection. No timing or calibration capacitors are required, simplifying layout and reducing BOM count.
AT42QT2120-XU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width)
- Series:
- QTouch™
- Packaging:
- Tube
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Buttons, Slider, Wheel
- Proximity Detection:
- Yes
- Number of Inputs:
- Up to 12
- LED Driver Channels:
- Up to 10
- Interface:
- I2C
- Resolution:
- -
- Voltage - Supply:
- 1.8V ~ 5.5V
- Current - Supply:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-TSSOP
AT42QT2120-XU FAQ
1.How can I place an order for AT42QT2120-XU through Aetrix?
Please submit a Request for Quotation (RFQ) for AT42QT2120-XU on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for AT42QT2120-XU reliable?
The price and inventory of AT42QT2120-XU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT42QT2120-XU is usually 5 days.
3.What payment methods are accepted for AT42QT2120-XU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT42QT2120-XU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT42QT2120-XU?
AT42QT2120-XU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT42QT2120-XU order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for AT42QT2120-XU?
For technical support, including AT42QT2120-XU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT42QT2120-XU requirements.
6.How does Aetrix verify that AT42QT2120-XU is sourced from the original manufacturer or authorized distributors?
All AT42QT2120-XU products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that AT42QT2120-XU meets industry standards.
7.What is the process for return or replacement of AT42QT2120-XU?
All AT42QT2120-XU units undergo pre-shipment inspection (PSI). If there is an issue with AT42QT2120-XU, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The AT42QT2120-XU part is unused and in its original packaging.
Return procedure for AT42QT2120-XU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT42QT2120-XU Tags
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IQS228B00000000TSR
Azoteq (Pty) Ltd
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MTCH101T-I/OT
Microchip Technology
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IQS323001CSR
Azoteq (Pty) Ltd
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MTCH102T-I/MS
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IQS323001DNR
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