NXP Semiconductors PCA9539BS,118

Overview

PCA9539BS,118 from NXP Semiconductors is a 24-pin HVQFN-packaged 16-bit I²C/SMBus GPIO expander with active-low interrupt and hardware reset, operating from 2.3 V to 5.5 V, supporting up to 400 kHz clock frequency, and featuring 5 V tolerant I/Os for mixed-voltage system interfacing - used in industrial control panels requiring remote push-button sensing and LED status indication.

For engineers reviewing the PCA9539BS,118 datasheet, PCA9539BS,118 pinout, PCA9539BS,118 application, or PCA9539BS,118 equivalent, this page delivers verified register-level I/O configuration behavior, HVQFN24 thermal pad layout guidance, interrupt edge-triggering logic, and precise RESET pin functional distinction between PCA9539 and PCA9539R variants.

Technical Context

The PCA9539BS,118 implements two independent 8-bit I/O ports (Port 0 and Port 1), each with dedicated configuration, input, output, and polarity inversion registers - enabling per-pin direction control and active-HIGH/LOW input inversion without external logic. Its open-drain INT output asserts when any configured input pin state differs from its corresponding input port register value.

It uses a fixed I²C target address (11101xx0/1) with A0/A1 pins selecting one of four device addresses on the same bus; the RESET pin performs full register + state machine reset in PCA9539BS,118 (unlike PCA9539RBS,118, where only the I²C interface resets). Power-on reset initializes all registers to default states, including all 16 I/Os as high-impedance inputs.

Key Specifications

Pinout & Package

HVQFN24 package (SOT616-1), 4 × 4 × 0.85 mm body with exposed thermal pad - requires soldering of center pad to PCB ground plane with thermal vias for reliable thermal dissipation and electrical stability.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9539RBS,118, PCA9539BS,118 guarantees full register reset on hardware assertion - essential for safety-critical restarts; versus TCA9539PWR, it eliminates pull-up current waste and supports stricter 5 V tolerance, making it preferable for industrial and medical applications demanding low IDD and robust voltage margins.

Availability

PCA9539BS,118 is available at Aetrix Electronics and suitable for industrial control panels, smart HVAC sensor hubs, PLC I/O modules, and medical device front panels requiring stable component supply across long production lifecycles.

Supply support for PCA9539BS,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 PCA9539 product line was developed to extend NXP's I²C-bus I/O expander family with low-power, interrupt-capable GPIOs for ACPI-compliant power switches, sensors, push buttons, LEDs, fans, and industrial human-machine interfaces.

FAQ

What is the exact I²C address range supported by PCA9539BS,118?

The PCA9539BS,118 uses a 7-bit fixed base address of 11101xx, where the two LSBs are set by A0 and A1 pins - yielding four possible addresses: 0x74, 0x75, 0x76, or 0x77. This allows up to four PCA9539BS,118 devices on the same I²C bus without address conflict. The R/W bit is appended during transmission, making the full 8-bit address either 0xE8–0xEE (write) or 0xE9–0xEF (read).

Does PCA9539BS,118 require external pull-up resistors on SCL and SDA lines?

Yes, PCA9539BS,118 requires external pull-up resistors on both SCL and SDA lines - its I²C interface uses open-drain outputs. Typical values are 2.2 kΩ to 10 kΩ depending on bus capacitance and speed; NXP recommends 4.7 kΩ for standard-mode (100 kHz) and 2.2 kΩ for fast-mode (400 kHz) operation with ≤400 pF total bus capacitance.

How does the INT pin behave when multiple input pins change state simultaneously on PCA9539BS,118?

The INT pin on PCA9539BS,118 asserts LOW whenever any input pin configured as an input differs from its corresponding bit in the Input Port register - regardless of how many pins change. It remains asserted until the relevant Input Port register (Port 0 or Port 1) is read, clearing the interrupt condition for that port. Simultaneous changes on both ports keep INT active until both ports are read.

Can PCA9539BS,118 drive LEDs directly, and what is the recommended configuration?

Yes, PCA9539BS,118 can drive LEDs directly in sink mode (I/O LOW = LED ON) using external current-limiting resistors. For lowest IDD, connect LED anode to VDD and cathode to I/O - ensuring VI ≥ VDD when OFF. Avoid sourcing current from I/O pins, as output high-drive strength is limited. Maximum recommended sink current per pin is 25 mA, with total package limit of 150 mA.

What is the function of the exposed thermal pad on the HVQFN24 package of PCA9539BS,118?

The exposed thermal pad on the PCA9539BS,118 HVQFN24 package (SOT616-1) is electrically connected to VSS and must be soldered to a PCB ground plane with ≥4 thermal vias (0.3 mm diameter) for optimal thermal dissipation and electrical stability. Leaving it unconnected degrades thermal resistance by >50% and may cause register corruption under sustained load.