Infineon Technologies CY8C20666AS-24LQXIT

Overview

CY8C20666AS-24LQXIT 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), 16 KB flash, 2 KB SRAM, and dedicated hardware for capacitive sensing of up to 33 buttons or 6 sliders. It supports I²C (up to 400 kHz), SPI (up to 12 MHz), USB 2.0 Full-Speed (12 Mbps), and operates from 1.71–5.5 V across –40 °C to +85 °C.

For engineers reviewing the CY8C20666AS-24LQXIT datasheet, CY8C20666AS-24LQXIT pinout, CY8C20666AS-24LQXIT application, or CY8C20666AS-24LQXIT equivalent, key selection criteria include SmartSense_EMC noise immunity, low-power wake-up scanning (28 µA/sensor @ 125 ms interval), configurable GPIO sink capability (25 mA per pin), integrated 10-bit ADC with internal reference, and QFN-48 package compatibility with USB-enabled layouts.

Technical Context

The device implements a dedicated CapSense analog block with patented CSA_EMC and CSD sensing algorithms, coupled with real-time SmartSense_EMC auto-tuning that dynamically adjusts sensor thresholds and IDAC settings to maintain stable performance under EMI stress and manufacturing variation. Its analog mux bus enables ganged proximity sensing by routing multiple sensors to shared comparators and reference buffers.

It features four clock sources - 6/12/24 MHz IMO, 32 kHz ILO, external 32 kHz crystal, and external clock input - enabling precise timing control for both CapSense scanning and system-level USB/I²C/SPI synchronization. The internal LDO provides high PSRR for analog subsystem stability independent of supply rail noise.

Key Specifications

Pinout & Package

This device is housed in a 48-pin QFN package (7 mm × 7 mm, 0.5 mm pitch) with exposed thermal pad, optimized for USB-capable CapSense applications requiring up to 33 sensing inputs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT42QT2120-MAHR and STM32F072CBT6, CY8C20666AS-24LQXIT delivers deterministic CapSense performance with zero-touch firmware tuning, integrated USB HID, and hardware-accelerated EMI rejection - making it optimal for production-ready, high-reliability touch interfaces where development schedule and EMC certification risk are critical.

Availability

CY8C20666AS-24LQXIT is available at Aetrix Electronics and suitable for home appliance control panels, industrial HMI terminals, medical device keypads, and consumer audio remotes requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for CY8C20666AS-24LQXIT 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 mixed-signal ICs for embedded systems, emphasizing configurable analog/digital blocks and system-on-chip integration.

This device belongs to the PSoC® CY8C20xx6A/AS family, engineered specifically for robust, production-ready capacitive touch interfaces with minimal external components and zero manual tuning overhead.

FAQ

What is the maximum number of capacitive sensors supported by CY8C20666AS-24LQXIT?

The CY8C20666AS-24LQXIT supports up to 33 capacitive buttons or 6 sliders, using its dedicated hardware CapSense block and configurable GPIOs. This count assumes standard electrode layout and excludes pins used for USB, I²C, or crystal oscillator functions. All 33 inputs can be scanned in under 10 ms with default SmartSense settings.

Does CY8C20666AS-24LQXIT require external components for basic CapSense operation?

No external components are required for basic CapSense operation. The device integrates IDACs, comparators, reference buffers, and a 1.0/1.2 V LDO. Only a single external modulator capacitor (typically 2.2 nF) on P0[1] or P0[3] is needed for CSD sensing. USB, I²C, and crystal interfaces use internal termination and biasing.

Can CY8C20666AS-24LQXIT operate from a single 3.3 V supply?

Yes. The device operates across 1.71–5.5 V, so 3.3 V is fully supported. At 3.3 V, GPIO sink current remains 25 mA per pin, USB signaling meets Full-Speed specifications, and SmartSense auto-tuning maintains full functionality. Internal LDO continues regulating analog reference independently.

Is PSoC Designer still supported for CY8C20666AS-24LQXIT firmware development?

Yes. Cypress provides long-term maintenance for PSoC Designer v5.4, including CapSense configuration tools, SmartSense tuning GUI, and USB HID descriptor generators. While newer PSoC devices use PSoC Creator or ModusToolbox, CY8C20xx6A/AS remains fully supported in the legacy IDE with all documented user modules and application notes.