NXP Semiconductors PCA9538D,118

Overview

PCA9538D,118 from NXP Semiconductors is an 8-bit I²C-bus/SMBus GPIO expander with interrupt and active-LOW reset, housed in a 16-pin SOIC package (SOT162-1). It provides configurable input/output pins, polarity inversion, and low standby current (≤1 µA), enabling expansion of microcontroller I/O for push-buttons, LEDs, and sensors in industrial control systems.

For engineers reviewing the PCA9538D,118 datasheet, PCA9538D,118 pinout, PCA9538D,118 application, or PCA9538D,118 equivalent, this device supports 2.3 V to 5.5 V operation, 400 kHz I²C clock, 5 V-tolerant I/Os, and hardware address selection via A0/A1 - critical for multi-device bus design and power-constrained embedded nodes.

Technical Context

The PCA9538D,118 implements a register-mapped I²C slave interface with four dedicated 8-bit registers: Configuration (I/O direction), Input Port (read-only state), Output Port (writeable output latch), and Polarity Inversion (input logic inversion). All registers are accessible via standard I²C write/read transactions using command-byte addressing without auto-increment.

Its interrupt output (INT) is open-drain and asserts when any configured input pin changes state relative to its Input Port register value; the active-LOW RESET pin triggers full register initialization without power cycling. Internal noise filtering on SCL/SDA and no-glitch power-up behavior ensure robust operation in electrically noisy environments.

Key Specifications

Pinout & Package

PCA9538D,118 is packaged in SO16 (SOT162-1): plastic small outline, 16 leads, body width 7.5 mm, lead pitch 1.27 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9539D,118, the PCA9538D,118 delivers optimal cost and space efficiency for ≤8 I/O needs; versus TCA9538PWR, it offers identical performance with NXP-specific support channels and long-term industrial lifecycle assurance.

Availability

PCA9538D,118 is available at Aetrix Electronics and suitable for industrial control panels, LED status subsystems, and sensor interface hubs requiring stable component supply, extended temperature operation, and I²C bus scalability.

Supply support for PCA9538D,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 focused on secure connectivity solutions for automotive, industrial, and IoT applications, with deep expertise in I²C ecosystem components.

The PCA9538D,118 belongs to NXP's I²C GPIO expander family, designed specifically to simplify I/O expansion in resource-constrained embedded systems while maintaining robustness, low power, and interoperability with SMBus hosts.

FAQ

What is the I²C address range supported by PCA9538D,118?

The PCA9538D,118 uses a fixed 7-bit base address of 1110000b, with the two least significant bits determined by A0 and A1 pins. This yields four possible addresses: 0x20, 0x21, 0x22, and 0x23. The PCA9538D,118 does not support software-configurable addresses - all addressing is hardware-defined via these two pins, ensuring deterministic bus allocation in multi-device systems.

Does PCA9538D,118 include internal pull-up resistors on its I/O pins?

No, the PCA9538D,118 explicitly omits internal I/O pull-up resistors - a key distinction from the PCA9554. This design choice reduces standby current when I/Os are held LOW, making PCA9538D,118 preferable for ultra-low-power applications. External pull-ups must be added where required, such as for open-drain sensor interfaces or I²C bus termination.

How does the interrupt (INT) pin of PCA9538D,118 behave during I/O reconfiguration?

When an I/O pin is changed from output to input on PCA9538D,118, a false interrupt may occur if the physical pin state differs from the stored value in the Input Port register. The INT pin asserts immediately upon mismatch detection and remains active until either the Input Port register is read or the pin returns to its prior logic level - confirming that interrupt handling must include register reads to clear pending events.

Can PCA9538D,118 operate with a 3.3 V supply while interfacing with 5 V sensors?

Yes, PCA9538D,118 supports VDD from 2.3 V to 5.5 V and features 5 V-tolerant I/Os - meaning IO0–IO7 accept input voltages up to 5.5 V regardless of VDD level. With VDD = 3.3 V, the PCA9538D,118 safely reads 5 V sensor outputs (e.g., TTL or CMOS logic) without damage or level-shifting circuitry, simplifying mixed-voltage system integration.

What is the maximum total output current allowed on PCA9538D,118 I/O pins?

The PCA9538D,118 limits total sourced current across all I/Os to 85 mA and total sunk current to 100 mA. Additionally, no single I/O pin may exceed ±25 mA. These constraints are specified in the datasheet's Static Characteristics tables and must be observed in layout and firmware - for example, driving multiple LEDs simultaneously requires current limiting per pin and aggregate load calculation to avoid exceeding the 100 mA sink limit.