Infineon Technologies CY8C20666A-24LTXI

Overview

CY8C20666A-24LTXI from Cypress Semiconductor is a programmable 1.8 V CapSense® controller with SmartSense™ auto-tuning, integrating an M8C 8-bit Harvard-architecture CPU (24 MHz max), 8 KB flash/1 KB SRAM, and dedicated hardware for capacitive sensing of up to 33 buttons or 6 sliders. It operates from 1.71–5.5 V, achieves 28 µA/sensor average current (125 ms scan interval), and supports full-speed USB 2.0 (12 Mbps) - deployed in human-interface consumer electronics requiring robust touch response under variable environmental noise.

For engineers reviewing the CY8C20666A-24LTXI datasheet, CY8C20666A-24LTXI pinout, CY8C20666A-24LTXI application, or CY8C20666A-24LTXI equivalent, key selection criteria include SmartSense_EMC noise immunity, on-chip 1 V analog reference stability, ILO/IMO clock flexibility, GPIO sink capability (25 mA per pin), and USB 2.0 compliance without external PHY.

Technical Context

The device implements a dedicated CapSense analog block with patented CSA_EMC and CSD sensing algorithms, paired with SmartSense_EMC real-time auto-tuning that dynamically adjusts sensor thresholds and IDAC settings during runtime to maintain signal-to-noise ratio across manufacturing variance and EMI stress. Its internal 1 V analog reference and low-dropout regulator deliver >60 dB PSRR for stable capacitive measurement.

It features a configurable analog mux bus connecting all GPIOs to dual high-speed comparators and a 10-bit incremental ADC, enabling ganged proximity sensing and analog front-end reuse. The M8C core executes firmware while the CapSense block runs autonomous scanning - decoupling timing-critical sensing from CPU load.

Key Specifications

Pinout & Package

Package: 48-pin QFN (7 mm × 7 mm, 0.5 mm pitch), RoHS-compliant, moisture sensitivity level 3.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MTCH101-I/ST and AT42QT2120-MMHR, CY8C20666A-24LTXI provides integrated USB HID, real-time SmartSense_EMC noise compensation, and programmable firmware - enabling adaptive touch performance in electrically noisy environments without external components or host MCU dependency.

Availability

CY8C20666A-24LTXI is available at Aetrix Electronics and suitable for consumer remote controls, industrial HMI panels, medical patient monitors, and home appliance control panels requiring stable component supply and long-term lifecycle support.

Supply support for CY8C20666A-24LTXI 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

Cypress Semiconductor (now part of Infineon Technologies) designs programmable system-on-chip solutions for embedded control, sensing, and connectivity applications.

CY8C20xx6A is part of the PSoC® CapSense® controller family, engineered specifically for robust, low-power capacitive touch interfaces in cost-sensitive, high-volume consumer and industrial products.

FAQ

Does CY8C20666A-24LTXI require external crystal for USB operation?

No. The device uses its internal 24 MHz IMO clock for USB full-speed operation, eliminating need for external crystal or oscillator. An external 32 kHz crystal is optional and only required for precise sleep timer or watchdog accuracy over temperature.

Can SmartSense auto-tuning be disabled for manual calibration?

Yes. SmartSense can be disabled via PSoC Designer configuration; users may then set fixed IDAC values, scan resolution, and baseline update rates. This mode is used for deterministic testing or legacy system compatibility where dynamic tuning is undesirable.

What is the maximum number of simultaneous CapSense buttons supported in QFN-48 package?

The CY8C20666A-24LTXI in 48-pin QFN supports up to 33 capacitive sensing inputs. All 33 pins are GPIOs assignable as buttons or sliders; two additional pins (P0[1], P0[3]) serve as modulator capacitor connections, not sensing inputs.

Is USB enumeration guaranteed without host-side driver installation?

Yes. The device implements standard USB HID class descriptors. When connected to Windows, macOS, or Linux hosts, it enumerates as a plug-and-play Human Interface Device without requiring custom drivers - supporting keyboard, mouse, or custom report descriptors out of the box.