AT42QT2120-MMHR - 12-Channel QTouchADC Touch Controller | Microchip
MPN: AT42QT2120-MMHR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.45 | $3.45 |
| 10 | $3.05 | $30.50 |
| 100 | $2.55 | $255.00 |
| 500 | $2.15 | $1,075.00 |
| 1,000 | $1.85 | $1,850.00 |
AT42QT2120-MMHR Overview
A capacitive touch controller is a mixed-signal IC that measures tiny changes in capacitance caused by a finger approaching or touching an electrode, then reports a debounced digital state to a host MCU. It sits in the signal-chain between input devices, capture/measurement hardware, and embedded microcontrollers; taxonomically: capacitive touch controller -> touch sensor IC -> sensor interface IC -> mixed-signal integrated circuit -> semiconductor. Because it converts an analog capacitance change into a robust, debounced digital signal over a robust serial bus, the device replaces mechanical switches and enables sealed, water-tolerant, and industrial-grade human-machine interfaces.
Key features include operation from 1.8 V to 5.5 V supply, configurable touch keys up to 12 channels, programmable slider/wheel support, on-chip drift compensation, integrated AKS-like simultaneous key arbitration, low standby current for power- and battery-management use cases, and a small 20-pin VQFN EP package that simplifies PCB layout in compact HMI modules. The QTouchADC acquisition algorithm uses self-capacitance sensing to deliver longer-range proximity detection than conventional projected-capacitance parts.
Architecturally, the device combines a charge-transfer analog front end, an internal reference capacitor network, and a finite-state machine that converts the analog burst waveform into debounced key status reported over I2C. This hardware state-machine approach offloads touch processing from the host MCU, allowing a low-cost microcontroller to manage the HMI. Internal slew-rate limited reference adjustment compensates for temperature, humidity, and mechanical drift without host intervention, ensuring long-term stability in consumer and industrial environments.
Typical applications include consumer appliance control panels, automotive center-stack touch keys, industrial HMI keypads, smart-home touch sliders, and proximity-activated wake-up interfaces. Wide supply range and low power also fit battery-susceptible and wearable human-interface devices.
When designing with this IC, follow Microchip's reference PCB layout for the VQFN exposed pad to ensure stable readings, and keep the I2C lines short with pull-ups per the SMBus specification. Plan electrode geometry per the datasheet's recommended touch-key layout, and reserve adequate ground copper around each touch node to avoid crosstalk.
This page synthesizes distributor stock and lead-time signals, verified drop-in compatible alternatives, and practical PCB layout guidance that is not repeated in the manufacturer datasheet.
Drop-in alternatives for AT42QT2120-MMHR — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with AT42QT2120-MMHR (same form factor and footprint) — differing in Communication Interface, Operating Temperature Range, Package.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
AT42QT1040-MMHR
✅ Drop-In✓ In Stock
$0.68 / Unit
View Datasheet →AT42QT1060-MMUR
✅ Drop-In📋 Reference alternative (not in catalog)
AT42QT2120-MMH
✅ Drop-In📋 Reference alternative (not in catalog)
AT42QT2120-MMHR Maximum Ratings & Electrical Characteristics
| Product Type | Capacitive Touch Controller |
| Number of Touch Channels | 12 (configurable) |
| Touch Sensing Algorithm | QTouchADC (self-capacitance, patent pending) |
| Configurable Touch Patterns | Buttons, sliders, wheels |
| Supply Voltage (VDD) | 1.8 V to 5.5 V |
| Communication Interface | I2C / SMBus-compatible |
| Drift Compensation | On-chip, slew-rate limited reference adjustment |
| Simultaneous Key Arbitration | Integrated (AKS-like) |
| Proximity Sensing | Yes, via self-capacitance |
| Operating Temperature Range | -40 C to +125 C (MM suffix: extended industrial) |
| Package | 20-pin VQFN (3x3 mm), exposed pad (MM package) |
| Mounting Type | Surface Mount |
| MSL (Moisture Sensitivity Level) | MSL3 / 260 C peak reflow (per Microchip MM package profile) |
| RoHS Status | Compliant |
| Reel Orientation | R (suffix to mirror standard reel carrier sheet direction) |
AT42QT2120-MMHR 20-pin vqfn (3x3 mm), exposed pad (mm package) Pin Configuration Guide
Pin configuration for AT42QT2120-MMHR (20-pin vqfn (3x3 mm), exposed pad (mm package) package). This analog component features input, output, and power supply pins. Refer to the manufacturer datasheet for offset null, compensation, and enable pin configurations. Ideal for signal conditioning and amplifier circuits.
No detailed pinout data available for AT42QT2120-MMHR.
Refer to the datasheet for full pin configuration.
Typical Applications
AT42QT2120-MMHR is suitable for 6 applications: Consumer Appliance Control Panel, Industrial HMI Keypad, Automotive Center-Stack Touch Keys, Smart-Home Touch Slider, Proximity Wake-Up Interface, Wearable Touch Interface.
Consumer Appliance Control Panel
The AT42QT2120-MMHR is well suited for sealed consumer-appliance control panels because its 12 QTouchADC channels cover the keypad, function buttons, and a slider for power level or volume. The on-chip drift compensation handles temperature and humidity swings around refrigerators, washing machines, and induction cooktops, while the 1.8 V to 5.5 V supply lets it share the appliance main rail without an additional LDO. The 20-pin VQFN (3x3 mm) package allows compact PCB layout behind glass or acrylic overlays.
Recommended
Industrial HMI Keypad
For industrial HMI keypads, the AT42QT2120-MMHR's 12 channels provide ample inputs for numeric keypads plus function keys, and its -40 C to +125 C operating range handles harsh factory environments. The on-chip AKS-like simultaneous-key arbitration prevents false triggers when multiple keys are pressed by a gloved hand. The integrated slew-rate limited reference adjustment compensates for drift caused by temperature swings, oil film, and humidity in factory conditions.
Recommended
Automotive Center-Stack Touch Keys
The AT42QT2120-MMHR can serve automotive center-stack touch keys where the 12 channels drive climate, volume, and menu keys behind a single decorative panel. The wide 1.8 V to 5.5 V supply range aligns with the typical 5 V automotive rail, while the on-chip drift handling compensates for cabin temperature swings from -40 C to +85 C and beyond. For full AEC-Q100 qualification, designers should pair this part with an automotive-grade host MCU and verify EMC behavior on the application PCB.
Recommended
Smart-Home Touch Slider
For smart-home wall controllers and dimmer sliders, the AT42QT2120-MMHR supports slider and wheel electrode patterns directly, with the 12 channels allocated to one or more sliders plus discrete buttons. The integrated I2C interface simplifies wiring to a low-cost Wi-Fi or BLE host MCU, and the low standby current is favorable for battery-backed wireless switches. The exposed-pad VQFN package also supports tight PCB layouts behind decorative glass panels.
Recommended
Proximity Wake-Up Interface
The AT42QT2120-MMHR's QTouchADC self-capacitance sensing enables longer-range proximity detection than projected-capacitance parts, allowing the IC to wake a host system when a hand approaches a control panel. This is useful in kiosk, medical device, and battery-powered applications where always-on sensing must coexist with product life targets. The integrated drift compensation ensures the proximity threshold does not drift over time.
Recommended
Wearable Touch Interface
For wearable devices such as smartwatches, earbuds cases, and fitness bands, the AT42QT2120-MMHR provides up to 12 capacitive touch inputs in a tiny 3x3 mm VQFN package, supporting a slider and buttons within a constrained PCB area. The wide 1.8 V to 5.5 V supply lets the IC share the Li-ion battery stack without a boost converter. The integrated drift compensation is essential for wearables that experience wide temperature and humidity swings during exercise and outdoor use.
Recommended
Recommended Products Summary
Engineering reference data for AT42QT2120-MMHR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | AT42QT1040-MMHR | AT42QT1060-MMUR | AT42QT2120-MMH |
|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 20-pin VQFN (3x3 mm) MM | 20-pin VQFN (3x3 mm) MM - same footprint | 20-pin VQFN (3x3 mm) MM - same footprint | 20-pin VQFN (3x3 mm) MM - same footprint |
| Touch Channels | 12 | 4 | 6 | 12 |
| Sensing Algorithm | QTouchADC (self-capacitance) | QTouchADC (self-capacitance) | QTouchADC (self-capacitance) | QTouchADC (self-capacitance) |
| Supply Voltage | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V |
| Operating Temperature | -40 C to +125 C | -40 C to +125 C | -40 C to +125 C | -40 C to +125 C |
| Communication Interface | I2C / SMBus | I2C / SMBus | I2C / SMBus | I2C / SMBus |
| Reel Orientation Suffix | R (standard) | R (standard) | U (alternate reel direction) | H (reverse reel direction) |
| Configurable Patterns | Buttons, sliders, wheels | Buttons | Buttons, sliders, wheels | Buttons, sliders, wheels |
Key Differentiators
- Highest channel count in the AT42QT21xx MM package family (vs AT42QT1040-MMHR)
- More configurable patterns than v1 (vs AT42QT1060-MMUR)
- Standard reel orientation vs alternate reel orientation variants (vs AT42QT2120-MMH)
Design Notes
Solder the exposed thermal pad of the 20-pin VQFN package to a continuous ground copper pour on the top and inner PCB layers. Stitch the ground pour with multiple vias around the EP. This provides a stable reference plane for capacitive measurements and improves thermal performance for continuous touch sensing in enclosed enclosures.
Route the I2C SDA and SCL lines as short as possible (target < 50 mm) and place 2.2 kohm to 10 kohm pull-ups to VDD near the host MCU side, not the touch controller. Keep switching power supply traces and high-frequency digital signals away from the touch electrodes to avoid injected crosstalk that can cause false triggers or reduced SNR.
Avoid placing ground copper or traces within the touch electrode active area - this forms a parasitic capacitance that reduces sensitivity. Reserve a minimum 5 mm clearance around each touch electrode on the top layer, and remove inner ground pours under the active touch area. Follow the electrode geometry recommendations in the Microchip datasheet (doc9634) to ensure reliable touch and proximity performance.
Compliance Information
RoHS and REACH compliant per Microchip product page. Not AEC-Q100 qualified as a standalone part - for AEC-Q100 applications, design with an automotive-grade host MCU and verify EMC behavior on the application PCB.
