NXP Semiconductors PCA9535HF,118

Overview

PCA9535HF,118 from NXP Semiconductors is a 16-bit I²C-bus/SMBus GPIO expander in HWQFN24 package, providing configurable input/output ports with active-low open-drain interrupt output, 2.3 V to 5.5 V supply operation, and 5 V-tolerant I/Os for ACPI power switches and sensor interfaces.

For engineers reviewing the PCA9535HF,118 datasheet, PCA9535HF,118 pinout, PCA9535HF,118 application, or PCA9535HF,118 equivalent, this device delivers low-standby-current I/O expansion with polarity inversion, noise-filtered SCL/SDA inputs, and hardware address selection via A0–A2 pins for multi-device bus sharing.

Technical Context

The PCA9535HF,118 implements two independent 8-bit port registers (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. Its I²C interface supports standard (100 kHz) and fast-mode (400 kHz) clock frequencies.

Power-on reset initializes all I/Os as high-impedance inputs and sets registers to default states; the open-drain INT output asserts when any input pin state differs from its corresponding Input Port register value, requiring read-back of that port to clear the interrupt condition.

Key Specifications

Pinout & Package

PCA9535HF,118 uses the HWQFN24 package (SOT994-1), featuring a 4 mm × 4 mm body, 0.75 mm height, and an exposed center thermal pad connected to VSS. The VSS pin and thermal pad must both be soldered to PCB ground for proper electrical and thermal performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9535PW,118 and PCA9555D,112, the PCA9535HF,118 offers superior thermal performance and smallest footprint among NXP's 16-bit I²C expanders, making it optimal for space-constrained, high-density industrial modules where power efficiency and heat dissipation are prioritized.

Availability

PCA9535HF,118 is available at Aetrix Electronics and suitable for industrial control panels, ACPI power management subsystems, and smart sensor hub interfaces requiring stable component supply across long production lifecycles.

Supply support for PCA9535HF,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 deep expertise in I²C ecosystem components and embedded interface IP.

The PCA9535 family was designed specifically to extend I²C-based system I/O capability in resource-constrained embedded designs - emphasizing low power, 5 V tolerance, and interrupt-driven responsiveness for real-time peripheral monitoring.

FAQ

What is the I²C address range supported by PCA9535HF,118?

The PCA9535HF,118 uses a fixed 7-bit base address of 0x20 (1000000b), with the three least-significant bits determined by A0–A2 pins. This yields eight possible slave addresses from 0x20 to 0x27, allowing up to eight PCA9535HF,118 devices on a single I²C bus without address conflict.

Does PCA9535HF,118 include internal pull-up resistors on its I/O pins?

No, the PCA9535HF,118 does not include internal pull-up resistors - unlike the PCA9555 variant. This omission significantly reduces standby current when I/Os are held LOW, making PCA9535HF,118 ideal for battery-powered or ultra-low-power applications where quiescent current must be minimized.

How is the interrupt output of PCA9535HF,118 cleared after assertion?

The INT pin of PCA9535HF,118 is cleared only by reading the Input Port register corresponding to the port where the state change occurred - e.g., reading Input Port 0 clears INT triggered by IO0_x pins. Reading the wrong port or writing to registers has no effect on the interrupt latch.

Can PCA9535HF,118 drive LEDs directly, and what design considerations apply?

Yes, PCA9535HF,118 can drive LEDs in sink configuration (anode to VDD, cathode to I/O). However, when LEDs are OFF, I/O voltage drops ~1.2 V below VDD, increasing supply current. To minimize IDD, use open-drain mode with external pull-up or ensure VDD ≤ LED forward voltage - a concern absent in PCA9535C variants.

What is the function of the exposed thermal pad on the HWQFN24 package of PCA9535HF,118?

The exposed center pad on PCA9535HF,118's HWQFN24 package is electrically connected to VSS and serves dual roles: it provides a low-impedance ground path for noise suppression and acts as a primary thermal conduction path to the PCB. For reliable operation, the pad must be soldered to a matching copper thermal pad with multiple vias to internal ground planes.