Infineon Technologies CY8C9540A-24PVXIT

Overview

CY8C9540A-24PVXIT from Cypress Semiconductor is a 40-bit I/O expander IC with integrated EEPROM and eight independently configurable 8-bit PWM channels, supporting I²C slave operation with clock stretching, programmable drive modes per pin (strong drive, open-drain, pull-up/down, high-Z), and interrupt-on-change functionality for system-level event detection in embedded control applications.

For engineers reviewing the CY8C9540A-24PVXIT datasheet, CY8C9540A-24PVXIT pinout, CY8C9540A-24PVXIT application, or CY8C9540A-24PVXIT equivalent, key selection criteria include I²C address flexibility via Extendable Soft Addressing (A0–A6), EEPROM write-disable (WD) pin support, user-default configuration storage in 11-Kbyte EEPROM, and per-pin drive mode configurability for mixed-signal board-level interfacing.

Technical Context

The CY8C9540A operates as two independent I²C slave devices on the same bus: one for multi-port I/O register access (base address 0x40–0x4F or 0xA0–0xAF depending on A0), and another for serial EEPROM access (base address 0x50–0x5F or 0xB0–0xBF). It requires I²C masters supporting clock stretching.

It features eight 8-bit PWM generators (PWM0–PWM7), each selectable to one of six internal clock sources (1.5 MHz, 93.75 kHz, 32 kHz, 24 MHz, or divided variants), with dedicated period, pulse width, divider, and enable registers - enabling precise timing control without host CPU overhead.

Key Specifications

Pinout & Package

CY8C9540A-24PVXIT 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).

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9555DWR and TCA6424ARGJR, CY8C9540A-24PVXIT delivers higher I/O density (40-bit), integrated PWM generation, larger EEPROM (11 KB), and flexible I²C addressing - making it uniquely suited for complex embedded systems requiring autonomous timing, persistent configuration, and scalable multi-device topologies.

Availability

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

Supply support for CY8C9540A-24PVXIT 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 high-performance mixed-signal ICs for embedded control, connectivity, and memory applications, with headquarters in San Jose, CA.

CY8C95xxA belongs to Cypress's programmable I/O expansion product line, engineered to offload GPIO, timing, and configuration management from host microcontrollers in resource-constrained embedded systems.

FAQ

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

No. The device requires I²C masters capable of clock stretching because internal EEPROM writes and register updates suspend SCL until completion. Masters that time out on stretched clocks will fail communication. Cypress confirms this requirement in Section 4 of Document 38-12036 Rev. *I.

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

Yes. When not assigned as I²C address bits, pins A1–A6 function as GPIOs within GPort1 and GPort2, as confirmed in Table 1 (Page 3) and Pin Descriptions (Page 9) of the datasheet. Their dual-role behavior is controlled by configuration registers.

How is EEPROM write protection enforced?

Write protection is enforced through two independent mechanisms: (1) hardware - pulling the WD pin high disables all EEPROM writes; (2) software - setting bit 7 of Config Register (29h) disables EEPROM access regardless of WD pin state.

What is the maximum PWM frequency achievable with CY8C9540A-24PVXIT?

The highest PWM frequency is 1.5 MHz (from the internal 1.5 MHz clock source with 1:1 prescaler and 0% duty cycle). With 8-bit resolution, minimum pulse width is ~167 ns. Actual usable frequency depends on selected clock source and divider register value (2Ch).