NXP Semiconductors PCF8575CTS/1,118

Overview

PCF8575CTS/1,118 from NXP Semiconductors (formerly Philips) is a 16-bit quasi-bidirectional I/O expander IC for I²C-bus systems, operating at 4.5–5.5 V with 400 kbit/s FAST-mode support, open-drain interrupt output, and latched outputs capable of directly driving LEDs. It serves as an I²C slave device to extend microcontroller GPIO in industrial control panels and embedded HMI interfaces.

For engineers reviewing the PCF8575CTS/1,118 datasheet, PCF8575CTS/1,118 pinout, PCF8575CTS/1,118 application, or PCF8575CTS/1,118 equivalent, key selection criteria include its 24-pin SSOP package, 16 I/O port architecture, interrupt-driven input change detection, and compatibility with standard I²C masters across automotive body control modules and programmable logic controllers.

Technical Context

The PCF8575CTS/1,118 implements a two-byte I²C transaction protocol where Port 0 (P00–P07) and Port 1 (P10–P17) are updated sequentially per write cycle, with automatic power-on reset setting all I/Os to high-impedance inputs. Its quasi-bidirectional ports require no direction-control signal and use transient pull-up current (IOHt) for fast rising edges on heavily loaded outputs.

Interrupt generation occurs on any rising or falling edge at input pins, with INT deactivation synchronized to read/write pulse edges - reset on rising edge of read pulse and definitively cleared on falling edge of write pulse. The device supports up to eight parallel instances via hardware address pins A0–A2.

Key Specifications

Pinout & Package

PCF8575CTS/1,118 is housed in a plastic shrink small outline package (SSOP24) with 24 leads, body width 5.3 mm (SOT340-1), optimized for surface-mount reflow assembly and space-constrained PCB layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar I²C I/O expander applications.

Compared with PCF8575CTS/1,118, PCA9555PW,118 offers broader voltage flexibility and register-level polarity control, while TCA9555RTWR delivers superior ESD robustness and nanoamp-level standby - both retain identical 16-bit quasi-bidirectional I/O functionality but differ in power, voltage, and protection trade-offs.

Availability

PCF8575CTS/1,118 is available at Aetrix Electronics and suitable for industrial control panels, automotive body controllers, and programmable logic controller I/O modules requiring stable component supply and long-term production continuity.

Supply support for PCF8575CTS/1,118 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

NXP Semiconductors is a global semiconductor leader specializing in secure connectivity solutions for automotive, industrial, and IoT applications, with roots in Philips' pioneering analog and mixed-signal IC development.

The PCF8575CTS/1,118 belongs to NXP's legacy I²C peripheral portfolio designed specifically for cost-sensitive, high-reliability embedded systems requiring simple, robust GPIO expansion without complex configuration overhead.

FAQ

What is the maximum I²C clock frequency supported by the PCF8575CTS/1,118?

The PCF8575CTS/1,118 supports FAST-mode I²C operation up to 400 kHz, as confirmed in Section 11 of the datasheet. This allows efficient 16-bit I/O updates in under 500 µs per transaction, making it suitable for real-time control loops in industrial automation where latency must remain below 1 ms.

Does the PCF8575CTS/1,118 require external pull-up resistors on SDA and SCL lines?

Yes, the PCF8575CTS/1,118 requires external pull-up resistors on both SDA and SCL lines, as specified in Section 7 of the datasheet. These resistors establish the HIGH state on the open-drain I²C bus and must be sized according to bus capacitance and desired rise time - typical values range from 2.2 kΩ to 10 kΩ for 400 kHz operation.

How does the interrupt output (INT) of the PCF8575CTS/1,118 behave during I/O state changes?

The INT pin of the PCF8575CTS/1,118 goes LOW on any rising or falling edge at input pins, remains asserted until the corresponding port data is read or written, and resets on the rising edge of the read-from-port pulse. This behavior enables edge-triggered interrupt handling in microcontrollers without continuous polling of the I²C bus.

Can the PCF8575CTS/1,118 drive LEDs directly without external current-limiting components?

Yes, the PCF8575CTS/1,118 can drive LEDs directly due to its latched outputs with high current drive capability - delivering up to 25 mA per pin at VOL = 1 V. However, a series current-limiting resistor is still required to set the LED forward current, as the device does not regulate current internally.

What is the power-on reset threshold voltage for the PCF8575CTS/1,118?

The power-on reset threshold voltage (VPOR) for the PCF8575CTS/1,118 is specified as 1.2 V minimum and 1.8 V maximum in Section 10 of the datasheet. When VDD rises above VPOR, the internal reset circuit releases and initializes all I/Os to high-impedance inputs, ensuring predictable startup behavior without external reset circuitry.