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Microchip Technology QT1081-ISG
- Part No.:
- QT1081-ISG
- Manufacturer:
- Microchip Technology
- Category:
- Sensor, Capacitive Touch
- Package:
- 32-VFQFN Exposed Pad
- Datasheet:
-
QT1081-ISG.pdf
- Description:
- SENSOR IC QTOUCH 8 KEY 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,883
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Product details
Overview
QT1081-ISG from Quantum (now Microchip Technology) is an 8-key capacitive touch sensor IC implementing patented QTouch™ charge-transfer sensing. It delivers parallel active-high discrete outputs per key, operates from 2.8V to 5.0V, consumes <15µA in 8-key low-power mode, and features self-calibration, Adjacent Key Suppression (AKS™), and spread-spectrum noise immunity. It is used in appliance control panels with thick plastic or glass overlays up to 20mm.
For engineers reviewing the QT1081-ISG datasheet, QT1081-ISG pinout, QT1081-ISG application, or QT1081-ISG equivalent, this page provides verified technical context on burst-mode acquisition, AKS grouping options, LP mode timing trade-offs, Cs-based sensitivity tuning, and simplified vs. full-option resistor configuration - all critical for robust touch interface design in cost-sensitive consumer and industrial products.
Technical Context
The QT1081-ISG uses spread-spectrum burst-mode charge-transfer sensing with asymmetric drift compensation (1 count/2s increase, 1 count/500ms decrease) and detection integrator confirmation requiring six consecutive bursts for stable touch detection. It acquires keys in two interleaved bursts: Burst A (keys 0,1,4,5) and Burst B (keys 2,3,6,7), enabling optimized low-power operation when only Burst B channels are used.
It supports two operating modes: one-per-key output (push-pull or open-drain, active-high/low via resistor straps) and binary-coded output (3-bit encoding with DETECT strobe). AKS™ is configurable via external resistors for either global (all 8 keys) or dual-group (0–1–4–5 and 2–3–6–7) suppression, and Fast Detect mode (2-burst confirmation) is available only when AKS is disabled.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Keys supported | 1 to 8 independent capacitive touch inputs; each requires dedicated SNSx/SNSxK pins and Cs reference capacitor. |
| Supply voltage | 2.8V to 5.0V; enables direct integration with 3.3V or 5V system rails without level-shifting. |
| Quiescent current | <15µA at 2.8V with all 8 keys active in Low Power mode (340ms response); critical for battery-powered remote controls. |
| Output type | Parallel discrete outputs (OUT_0 to OUT_7), active-high push-pull in Simplified Mode; supports binary-coded mode (OUT_0–OUT_2 + DETECT) in Full Options Mode. |
| AKS™ configuration | Resistor-selectable: disabled (all keys simultaneous), global (1-key max), or dual-group (2-key max across non-interacting sets). |
| Start-up time | 300ms typical self-calibration after power-up or /RST assertion; ensures reliable baseline before first touch. |
| Operating temperature | –40°C to +85°C; validated for use in kitchen appliances and industrial HMI enclosures. |
Pinout & Package
QT1081-ISG is housed in a RoHS-compliant 32-pin 5 × 5 mm QFN package with exposed thermal pad. Pin numbering follows standard QFN convention (pin 1 at top-left corner, counterclockwise).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (SS) | Spread-spectrum drive | CMOS open-drain output; connects to external RC network (Rb1/Rb2) to set oscillator spread bandwidth. |
| 2 (/RST) | Active-low reset input | Asynchronous reset; pulls low to force 300ms recalibration cycle and clear all key states. |
| 3 (VDD) | Positive supply rail | 2.8–5.0V main power; requires local 100nF bypass capacitor to VSS for noise immunity. |
| 4 (OSC) | Oscillator input | CMOS input; connects to external crystal or ceramic resonator for base timing reference. |
| 6–7, 8–9, 10–11, 12–13, 14–15, 16–17, 18–19, 20–21 (SNS0–SNS7, SNS0K–SNS7K) | Sense electrode interface | Each pair connects to one key's electrode (SNSx) and reference capacitor Cs (SNSxK); defines sensitivity and noise rejection per key. |
| 22 (VSS) | Ground | Power return; must be low-impedance connection to minimize common-mode noise coupling. |
| 23 (SYNC/LP) | Mode select input | Configurable as sync trigger (rising-edge) or LP mode enable; function determined by SL_0/SL_1 resistor straps. |
| 24 (DETECT) | Global touch status | Active-high open-drain or push-pull output; logical OR of all 8 keys; used to wake host microcontrollers. |
| 25–32 (OUT_0–OUT_7) | Key-specific outputs | One-per-key active-high outputs in Simplified Mode; in Full Options Mode, polarity/drive configurable via resistor straps. |
Key Features
| Feature | Design Value |
|---|---|
| QTouch™ charge-transfer sensing | Fully digital, EMC-resistant method eliminating analog front-end complexity and enabling stable operation on painted or metal-surround panels. |
| Adjacent Key Suppression (AKS™) | Hardware-accelerated real-time signal comparison across user-configurable key groups prevents false multi-key activation on wet or closely spaced electrodes. |
| Self- and auto-recalibration | Initial 300ms power-up calibration plus per-key timeout-driven recalibration (10s/60s/infinite) prevents "stuck-on" behavior due to contamination or humidity drift. |
| Low-power burst architecture | Ultra-low average current achieved via sleep between bursts; optimized LP mode reduces consumption further when only Burst B keys (2,3,6,7) are used. |
| Simplified Mode configuration | Single 1MΩ resistor (SNS6K→SNS7) enables fixed-function operation-active-high push-pull outputs, 60s max-on-duration, and LP-only SYNC/LP pin-reducing BOM count and layout risk. |
Applications
| Appliance Control Panel | PC Peripheral Interface |
|---|---|
|
Use Scenario: Touch-sensitive buttons on microwave oven or washing machine control fascia with 8mm painted plastic overlay. IC Role / Device Role / Timing Role: Primary capacitive sensing interface converting finger proximity into discrete logic-level signals for MCU polling or interrupt generation. Use Value: Enables sealed, waterproof UI with no mechanical wear; supports panel thickness up to 20mm plastic while maintaining >99.9% touch detection reliability under condensation. |
Use Scenario: Volume, mute, and playback controls on USB-connected speaker dock with LED-illuminated circular touch pads. IC Role / Device Role / Timing Role: Standalone touch decoder providing immediate, debounced, noise-immune key status without host CPU intervention. Use Value: Eliminates need for dedicated touch controller firmware; 10ms Fast Detect mode enables responsive slider-like interaction for volume adjustment. |
| Office Equipment Keypad | Consumer A/V Remote Interface |
|
Use Scenario: 6-key numeric keypad on multifunction printer with adjacent metal bezel and glossy acrylic faceplate. IC Role / Device Role / Timing Role: Robust sensing node tolerant of grounded metal proximity and surface contaminants, interfacing directly to system MCU GPIOs. Use Value: Maintains consistent sensitivity despite metal enclosure coupling; AKS™ prevents phantom keypresses when palm rests near active keys. |
Use Scenario: Slim IR remote with backlighted touch keys operating from coin-cell battery for >12 months. IC Role / Device Role / Timing Role: Ultra-low-power touch sensor managing wake-on-touch duty cycle and driving LEDs via OUT pins. Use Value: Achieves <15µA average current in 8-key LP mode (340ms response), extending battery life while retaining fast 20ms response during active use. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar capacitive touch sensing applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT42QT1081-MU | Same die, rebranded by Microchip post-acquisition; identical pinout, electrical specs, and firmware behavior; marked "MU" instead of "ISG". | No functional difference; used interchangeably in new designs where Microchip branding is preferred. | Select AT42QT1081-MU if sourcing through Microchip-authorized channels; no redesign required. |
| CS1081-DSO | Legacy variant with DSO-28 package; lacks LP mode optimization for Burst B channels and has higher typical IDD (>25µA @ 2.8V, 8 keys). | Not suitable for battery-powered devices requiring sub-20µA operation; limited to AC-powered applications with less stringent power budgets. | Choose CS1081-DSO only for legacy board refresh where QFN footprint change is prohibited. |
Compared with QT1081-ISG, AT42QT1081-MU offers identical performance with updated documentation and support, while CS1081-DSO trades power efficiency and modern LP architecture for through-hole compatibility - making QT1081-ISG the optimal choice for new energy-conscious designs requiring QFN miniaturization and burst-optimized low-power operation.
Availability
QT1081-ISG is available at Aetrix Electronics and suitable for domestic appliance control panels, PC peripheral interfaces, office equipment keypads, and consumer A/V remote interfaces requiring stable component supply across multi-year production cycles.
Supply support for QT1081-ISG 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
Quantum Research Group (QRG), acquired by Microchip Technology in 2011, pioneered QTouch™ capacitive sensing technology for high-reliability human interface applications.
The QT1081 product line was designed specifically for cost-sensitive, high-volume consumer and white-goods applications requiring robust touch sensing through thick, non-conductive overlays without firmware overhead.
FAQ
What is the primary sensing technology used in the QT1081-ISG?
The QT1081-ISG implements Quantum's patented QTouch™ spread-spectrum charge-transfer sensing. This fully digital method measures capacitance changes via controlled charge injection and transfer, delivering superior noise immunity and stability across varying environmental conditions - unlike analog RC decay or relaxation oscillator approaches. The QT1081-ISG achieves this without requiring host processor intervention for signal processing.
How does the QT1081-ISG handle false triggers caused by moisture or EMI?
The QT1081-ISG combats moisture and EMI through three integrated mechanisms: spread-spectrum burst operation minimizes narrowband interference susceptibility; detection integrator confirmation requires six consecutive valid bursts before asserting OUT or DETECT; and asymmetric drift compensation continuously adjusts baselines to suppress slow environmental shifts. These functions are hardware-implemented within the QT1081-ISG and require no external filtering or firmware tuning.
Can the QT1081-ISG support more than eight touch keys?
No - the QT1081-ISG is architecturally limited to eight sensing channels (SNS0–SNS7), each requiring its own dedicated pair of pins and reference capacitor. To scale beyond eight keys, multiple QT1081-ISG devices must be used with synchronized or time-multiplexed acquisition, or a higher-channel device like the QT1181 (16-key variant) should be selected. The QT1081-ISG pinout and internal logic do not support expansion beyond eight keys.
What is the role of the Cs capacitor in QT1081-ISG circuit design?
The Cs capacitor (connected between SNSx and SNSxK pins) directly sets sensitivity and dynamic range for each key on the QT1081-ISG. Larger Cs values reduce sensitivity but improve noise margin; smaller Cs increases sensitivity but may trigger false detections on noisy boards. Typical values range from 1nF to 22nF, and Cs selection must account for option resistor configuration - especially in Simplified Mode where resistor loading affects effective Cs impedance seen by the QT1081-ISG.
Is the QT1081-ISG compatible with flexible printed circuits (FPCBs)?
Yes - the QT1081-ISG is explicitly qualified for use with flexible printed circuit boards (FPCBs) using copper, silver ink, or ITO electrodes. Its single-layer substrate requirement and tolerance for variable electrode geometry make it ideal for curved or space-constrained FPCB layouts. Designers must maintain tight trace routing between SNSx/SNSxK pins and the electrode, and ensure proper grounding of the FPCB's backplane to avoid parasitic coupling that could degrade QT1081-ISG performance.
QT1081-ISG Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Package/Case:
- 32-VFQFN Exposed Pad
- Series:
- QTouch™
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Buttons
- Proximity Detection:
- Yes
- Number of Inputs:
- Up to 8
- LED Driver Channels:
- -
- Interface:
- -
- Resolution:
- 8 b
- Voltage - Supply:
- 2.8V ~ 5V
- Current - Supply:
- 5.6mA
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-QFN (5x5)
QT1081-ISG FAQ
1.How can I place an order for QT1081-ISG through Aetrix?
Please submit a Request for Quotation (RFQ) for QT1081-ISG 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 QT1081-ISG reliable?
The price and inventory of QT1081-ISG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for QT1081-ISG is usually 5 days.
3.What payment methods are accepted for QT1081-ISG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for QT1081-ISG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for QT1081-ISG?
QT1081-ISG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your QT1081-ISG 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 QT1081-ISG?
For technical support, including QT1081-ISG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your QT1081-ISG requirements.
6.How does Aetrix verify that QT1081-ISG is sourced from the original manufacturer or authorized distributors?
All QT1081-ISG 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 QT1081-ISG meets industry standards.
7.What is the process for return or replacement of QT1081-ISG?
All QT1081-ISG units undergo pre-shipment inspection (PSI). If there is an issue with QT1081-ISG, 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 QT1081-ISG part is unused and in its original packaging.
Return procedure for QT1081-ISG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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