NXP Semiconductors PCAL6524HEHP

Overview

PCAL6524HEHP from NXP Semiconductors is a 24-bit I²C-bus I/O expander with Agile I/O features, supporting Fast-mode Plus (1 MHz), ultra-low-voltage interface (0.8 V I²C side), bidirectional level translation between 0.8–3.6 V (I²C) and 1.65–5.5 V (Port P), and integrated interrupt output. It enables GPIO expansion in space-constrained, battery-powered systems such as portable medical sensors and handheld industrial HMIs.

For engineers reviewing the PCAL6524HEHP datasheet, PCAL6524HEHP pinout, PCAL6524HEHP application, or PCAL6524HEHP equivalent, key selection criteria include its dual-supply architecture (VDD(I2C-bus)/VDD(P)), programmable drive strength per port, hardware switch debounce, and bit-wise interrupt edge/mask configuration - all critical for low-power mixed-voltage embedded designs.

Technical Context

The PCAL6524HEHP implements a dual-rail architecture: VDD(I2C-bus) (0.8–3.6 V) sets SCL/SDA logic levels and enables bidirectional voltage translation, while VDD(P) (1.65–5.5 V) powers Port P and defines I/O voltage tolerance. Its Agile I/O engine supports per-pin configuration of pull-up/pull-down, latch mode, and open-drain/push-pull outputs.

Interrupt handling includes edge- or level-triggered detection per bit, individual interrupt clear without disturbing other pending events, and an interrupt status register for rapid source identification. The device also integrates hardware switch debounce (configurable count and enable per port) and I²C software reset via General Call address 00h + data byte 06h.

Key Specifications

Pinout & Package

PCAL6524HEHP uses a 32-terminal HUQFN package (5 mm × 5 mm × 0.56 mm, SOT1426-1), optimized for high-density PCB layouts and thermal performance in compact portable electronics.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TCA6424A and PCA9555, PCAL6524HEHP delivers unique value in ultra-low-voltage I²C interfacing, per-pin interrupt control, and hardware-assisted reliability features - making it the only option among the three that supports true 0.8 V microcontrollers while maintaining robust operation across 5 V peripheral domains.

Availability

PCAL6524HEHP is available at Aetrix Electronics and suitable for portable medical sensors, industrial handheld HMIs, smart home sensor nodes, and automotive body control modules requiring stable component supply and long-term production continuity.

Supply support for PCAL6524HEHP 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 mixed-signal and interface ICs.

The PCAL6524HEHP belongs to NXP's Agile I/O family - engineered specifically for low-power, mixed-voltage embedded systems needing intelligent GPIO expansion without sacrificing signal integrity or design flexibility.

FAQ

What is the maximum I²C clock frequency supported by PCAL6524HEHP?

The PCAL6524HEHP fully complies with Fast-mode Plus (Fm+) I²C-bus specification and operates reliably up to 1 MHz. This enables high-speed polling of all 24 I/O states within microseconds, reducing host MCU latency in time-critical sensor aggregation tasks. The device maintains timing compliance across its full 0.8–3.6 V VDD(I2C-bus) range.

How does PCAL6524HEHP handle voltage level translation between different supply domains?

PCAL6524HEHP uses a dual-supply architecture: VDD(I2C-bus) (0.8–3.6 V) defines SCL/SDA logic thresholds and enables bidirectional translation, while VDD(P) (1.65–5.5 V) powers Port P and determines I/O voltage tolerance. No external level shifters are needed - the chip internally translates signals between incompatible voltage rails, e.g., 0.85 V MCU ↔ 3.3 V sensor.

Can PCAL6524HEHP drive LEDs directly, and what is its output current capability?

Yes, PCAL6524HEHP can drive LEDs directly: each Port P pin supports up to 25 mA sink current in push-pull or open-drain mode. This eliminates external driver transistors for status indicators and reduces BOM count. Output drive strength is programmable per pin to optimize rise/fall times and minimize EMI in sensitive analog sections.

Does PCAL6524HEHP support hardware-based switch debounce, and how is it configured?

Yes, PCAL6524HEHP integrates dedicated hardware switch debounce logic. It is enabled per port via registers 74h (debounce enable 0) and 75h (debounce enable 1), with a shared debounce counter adjustable in register 76h. This offloads timing-critical debouncing from firmware, ensuring consistent response across varying MCU load conditions and eliminating software jitter.

What is the purpose of the ADDR pin on PCAL6524HEHP, and how many devices can share the same I²C bus?

The ADDR pin on PCAL6524HEHP selects one of four fixed I²C slave addresses (40h, 42h, 44h, or 46h) by connecting it to VDD(I2C-bus), SCL, SDA, or VSS. This allows up to four PCAL6524HEHP devices to coexist on the same I²C bus without address conflict - essential for modular sensor hubs or multi-zone control systems requiring scalable GPIO expansion.