Infineon Technologies CY8C20666A-24LTXIT

Overview

CY8C20666A-24LTXIT 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 supports full-speed USB 2.0 (12 Mbps), I²C (up to 400 kHz), and SPI (up to 12 MHz), and operates across 1.71–5.5 V with deep-sleep current as low as 0.1 µA - deployed in human-interface consumer electronics requiring robust touch response under variable EMI conditions.

For engineers reviewing the CY8C20666A-24LTXIT datasheet, CY8C20666A-24LTXIT pinout, CY8C20666A-24LTXIT application, or CY8C20666A-24LTXIT equivalent, key selection criteria include SmartSense_EMC noise immunity, configurable GPIO sink capability (25 mA per pin), integrated 10-bit ADC with internal reference, and QFN-24 package compatibility with 17-capacitive-sensing-input configurations.

Technical Context

The device implements a dedicated CapSense analog block with patented CSA_EMC and CSD sensing algorithms, enabling real-time sensor calibration without host intervention. Its SmartSense_EMC algorithm dynamically adjusts baseline, sensitivity, and noise thresholds to maintain stable button detection amid conducted/radiated EMI - critical for CE/FCC-compliant consumer enclosures.

It features four independent clock sources: 6/12/24 MHz IMO, 32 kHz ILO, external 32 kHz crystal, and external clock input - allowing precise timing control for both CapSense scanning (e.g., 125 ms wake-up interval) and USB frame synchronization. The internal LDO supplies regulated analog voltage with high PSRR, decoupling sensor performance from supply ripple.

Key Specifications

Pinout & Package

Package: 24-pin QFN (4 × 4 mm, 0.5 mm pitch), exposed thermal pad, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MTCH6302-I/ST and AT42QT2120-MMHR, CY8C20666A-24LTXIT uniquely combines programmable M8C core, full-speed USB HID, SmartSense_EMC noise immunity, and integrated analog resources - making it optimal for upgradable, multi-function HMI systems requiring field calibration and mixed-signal integration.

Availability

CY8C20666A-24LTXIT is available at Aetrix Electronics and suitable for consumer remote controls, appliance touch panels, medical handheld interfaces, and interactive kiosk front panels requiring stable component supply and long-term manufacturing continuity.

Supply support for CY8C20666A-24LTXIT 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, with headquarters in San Jose, CA.

CY8C20xx6A is part of Cypress's CapSense® controller family, engineered specifically for robust, low-power capacitive touch interfaces in cost-sensitive consumer and industrial HMI systems - emphasizing auto-tuning, EMI resilience, and rapid prototyping via PSoC Designer.

FAQ

What is the maximum number of capacitive sensors supported in the QFN-24 package?

The CY8C20666A-24LTXIT in its 24-pin QFN package supports up to 17 capacitive sensing inputs. This configuration is documented in the official datasheet (001-54459 Rev. *Y, page 11) and validated through Cypress's pinout mapping for the "24-pin QFN (17 Sensing Inputs)" variant. Sensor count is constrained by available GPIOs assigned to CapSense functionality, not flash size or CPU capability.

Does SmartSense auto-tuning require host processor intervention during operation?

No. SmartSense auto-tuning runs autonomously within the dedicated CapSense hardware block using on-chip IDACs, comparators, and counters. It continuously monitors signal-to-noise ratio and adjusts baseline, finger threshold, and scan parameters in real time - without CPU cycles, firmware polling, or external calibration routines. This is confirmed in the SmartSense_EMC technical description (page 5) and AN73034 design guide.

Can the internal 10-bit ADC measure external voltages beyond the VDD rail?

No. The 10-bit incremental ADC uses an internal voltage reference (1.024 V or 1.2 V, selectable) and accepts inputs only within 0 V to VREF. It cannot measure signals exceeding VDD or below VSS. External signal conditioning (e.g., resistor divider + op-amp buffer) is required for higher-voltage measurements - as specified in the ADC Electrical Specifications section (page 25) of the datasheet.

Is the USB interface limited to HID class, or does it support custom descriptors?

The USB interface supports fully customizable descriptors via firmware. While default PSoC Designer templates implement HID keyboard/mouse classes, the USB user module allows defining vendor-specific descriptors, bulk/interrupt endpoints, and custom class requests. This is demonstrated in the CY8C20xx6A TRM (section 12.3.2) and verified in application note AN64846, which shows descriptor modification for non-HID use cases.