Infineon Technologies CY8C9540A-24PVXI

Overview

CY8C9540A-24PVXI from Cypress Semiconductor is a 40-bit I/O expander IC with integrated EEPROM and eight independently configurable 8-bit PWM outputs, supporting I²C/SMBus-compatible communication with clock stretching, 3.3 V operation, and internal 11-Kbyte user-accessible EEPROM for persistent configuration storage. It serves as a dual-function I²C slave-simultaneously acting as a multi-port I/O controller and serial EEPROM-enabling GPIO expansion in space-constrained embedded control systems such as industrial HMIs and sensor interface modules.

For engineers reviewing the CY8C9540A-24PVXI datasheet, CY8C9540A-24PVXI pinout, CY8C9540A-24PVXI application, or CY8C9540A-24PVXI equivalent, key selection criteria include I²C address flexibility via Extendable Soft Addressing (A0–A6), interrupt-driven input change detection, EEPROM write-disable (WD) pin support, and per-pin drive mode configurability (strong drive, open-drain, pull-up/down, high-Z).

Technical Context

The device implements two independent I²C slave interfaces on a shared bus: one for register-mapped I/O control (using 7-bit base address 0x40/0x50 with A0–A6 extension), and another for EEPROM access (base address 0xA0/0xB0). All 40 I/O pins are grouped across GPort0–GPort5, with GPort1 and GPort2 offering configurable pins that double as address inputs (A1–A6) or write-disable (WD).

It features eight 8-bit PWM generators (PWM0–PWM7), each selectable per-pin via the Select PWM register and clocked by one of six internal sources (1.5 MHz, 93.75 kHz, 32 kHz, 24 MHz, or divided variants). Configuration registers-including Port Direction, Drive Mode, Inversion, and Interrupt Mask-are volatile but persistable to EEPROM using dedicated store/restore commands.

Key Specifications

Pinout & Package

The CY8C9540A-24PVXI is housed in a 48-pin LQFP package (7 mm × 7 mm, 0.5 mm pitch) with exposed thermal pad. Pin functions are validated per Cypress Document 38-12036 Rev. *I (Page 6, "48-Pin Part Pinout").

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar I/O expansion applications.

Compared with TCA6424A and PCA9555, CY8C9540A-24PVXI uniquely integrates EEPROM-based configuration retention and eight PWM channels-reducing system-level component count and eliminating software overhead for state restoration and LED/timing control.

Availability

CY8C9540A-24PVXI is available at Aetrix Electronics and suitable for industrial HMI panels, smart sensor nodes, and automotive body control modules requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for CY8C9540A-24PVXI 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, connectivity, and sensing applications, with global R&D and manufacturing infrastructure.

The CY8C95xxA family targets resource-constrained embedded systems needing scalable GPIO expansion, nonvolatile configuration, and integrated PWM-eliminating discrete logic and external memory in industrial and IoT edge devices.

FAQ

Does CY8C9540A-24PVXI support standard I²C masters without clock stretching?

No. The CY8C9540A-24PVXI requires I²C masters capable of clock stretching to accommodate internal EEPROM write cycles and register access latency. Masters that time out on stretched clocks-such as some SMBus controllers-will fail communication. Cypress confirms this requirement in Section 4 ("Device Access Addressing") and AC Electrical Characteristics (Page 19) of datasheet 38-12036 Rev. *I.

How is the 11-Kbyte EEPROM organized and accessed?

The EEPROM is byte-addressable using two-byte addressing (AHI/ALO), supporting up to 28 Kbytes; CY8C9540A uses 11 Kbytes. Reads and writes occur over the dedicated EEPROM I²C slave address (0xA0–0xBF). Writes are blocked if the WD pin is high or if the Config register disables EEPROM. User-default settings occupy a reserved EEPROM subsection and load automatically at power-on.

Can unused address pins (A1–A6) be used as general-purpose I/O?

Yes. When not assigned as I²C address bits in the Extendable Soft Addressing scheme, pins A1–A6 function as additional GPIOs within GPort1 or GPort2, as confirmed in Table 1 ("GPIO Availability") and Pin Descriptions (Page 9) of the datasheet. Their role is determined at runtime via configuration registers-not fixed at manufacture.

What happens to I/O states during power-up before EEPROM defaults are loaded?

At power-on, all I/O pins default to weak pull-up (factory setting) until the EEPROM-stored user defaults are loaded-typically within 10–20 ms after Vdd stabilization. This behavior is enforced by the internal Power-On Reset (POR) circuit and documented in the "Power-on-Reset" section (Page 1) and Register Descriptions (Page 12–13). No external initialization sequence is required.