NXP Semiconductors PCA9537DP,118

Overview

PCA9537DP,118 from NXP Semiconductors is a 4-bit I²C-bus/SMBus GPIO expander with interrupt and active-low reset, operating from 2.3 V to 5.5 V, featuring 5 V-tolerant I/Os, open-drain INT output, and default input configuration at power-on. It serves as a low-power I/O extension solution for ACPI power switches, push-buttons, LEDs, and sensors in embedded control subsystems.

For engineers reviewing the PCA9537DP,118 datasheet, PCA9537DP,118 pinout, PCA9537DP,118 application, or PCA9537DP,118 equivalent, key selection considerations include its fixed I²C address (0x49), TSSOP10 package, 400 kHz Fast-mode support, 0.25 μA standby current, and register-level polarity inversion capability.

Technical Context

The PCA9537DP,118 implements a synchronous I²C slave interface with four configurable I/O pins managed via four dedicated registers: Configuration (input/output direction), Input Port (read-only state mirroring), Output Port (writeable output latch), and Polarity Inversion (bitwise active-HIGH/LOW inversion). All registers are accessed using an explicit command byte (0–3) following the device address.

Its interrupt logic activates the open-drain INT pin when any input-configured I/O changes state relative to the Input Port register value; reading the Input Port register clears the interrupt condition. The active-low RESET pin and internal power-on reset both initialize all registers to default states, including all I/Os as high-impedance inputs.

Key Specifications

Pinout & Package

TSSOP10 package (SOT552-1), 3 mm body width, 0.5 mm lead pitch, surface-mount, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar GPIO expander applications.

Compared with PCA9537DP,118, PCA9537DPZ offers identical functionality with enhanced ESD packaging, while TCA6408A trades the dedicated RESET and fixed-address simplicity for greater I/O count and address configurability - making it suitable for scalable multi-expander systems.

Availability

PCA9537DP,118 is available at Aetrix Electronics and suitable for industrial HMI panels, LED status banks, ACPI power switch interfaces, and temperature sensor subsystem monitors requiring stable component supply across extended product lifecycles.

Supply support for PCA9537DP,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 core expertise in interface, power management, and embedded processing technologies.

The PCA9537DP,118 belongs to NXP's I²C-bus GPIO expander family, designed specifically to simplify I/O expansion in resource-constrained embedded controllers while maintaining low power, high noise immunity, and seamless integration with ACPI and SMBus-based power management architectures.

FAQ

What is the I²C address of the PCA9537DP,118 and can it be changed?

The PCA9537DP,118 has a fixed 7-bit I²C address of 0x49 (1001001b), with no provision for address modification via pins or registers. This design ensures deterministic bus behavior in single-device configurations but requires careful system-level I²C address planning when multiple expanders are used. The PCA9537DP,118 datasheet confirms this address is hardwired and non-configurable.

Does the PCA9537DP,118 support both standard-mode and fast-mode I²C communication?

Yes, the PCA9537DP,118 supports standard-mode I²C up to 100 kHz and fast-mode I²C up to 400 kHz, as verified in Section 10 of the official datasheet. Its SCL/SDA inputs include integrated noise filters, and timing parameters such as tLOW, tHIGH, and tSU;DAT are specified for both modes - enabling reliable operation in mixed-speed I²C systems.

How does the interrupt (INT) pin on the PCA9537DP,118 behave and how is it cleared?

The PCA9537DP,118 INT pin is an active-low, open-drain output that asserts when any input-configured I/O changes state relative to its stored value in the Input Port register. The interrupt is automatically cleared upon reading the Input Port register (command byte 0x00), not by writing to any register or toggling RESET. This behavior is explicitly defined in Section 6.5 of the PCA9537DP,118 datasheet.

What happens to the I/O pins of the PCA9537DP,118 during power-on or RESET assertion?

During power-on reset or when the RESET pin is held LOW, all four I/O pins (IO0–IO3) default to high-impedance inputs, and all internal registers (Configuration, Input Port, Output Port, Polarity Inversion) initialize to their documented default values. This behavior is guaranteed by the internal POR circuit and is confirmed in Sections 6.3 and 6.4 of the PCA9537DP,118 product data sheet.

Is the PCA9537DP,118 pin-compatible with other NXP 4-bit I/O expanders like the PCA9536?

No, the PCA9537DP,118 is not pin-compatible with the PCA9536. While both are 4-bit I²C expanders in TSSOP10 packages, the PCA9536 lacks the dedicated RESET pin and uses a different pinout (e.g., RESET on PCA9537DP,118 Pin 6 is unused on PCA9536). The PCA9537DP,118 datasheet Figure 2 and Table 3 confirm its unique 10-pin assignment, including RESET and INT functions absent in PCA9536.