Nexperia USA Inc. NCA9555BYHP

Overview

NCA9555BYHP from Nexperia is a low-voltage 16-bit I²C/SMBus GPIO expander with interrupt output, 1.65 V to 5.5 V supply range, open-drain INT pin, and configurable input/output registers. It provides parallel port expansion for microcontroller-based systems where board space and I²C bus loading are constrained-e.g., industrial sensor hubs requiring synchronized input monitoring and LED status feedback.

For engineers reviewing the NCA9555BYHP datasheet, NCA9555BYHP pinout, NCA9555BYHP application, or NCA9555BYHP equivalent, key selection criteria include its 400 kHz Fast-mode I²C support, 25 mA per-pin push-pull output drive, hardware-configurable slave address (A0–A2), polarity inversion capability, and power-on reset behavior ensuring deterministic register initialization.

Technical Context

The NCA9555BYHP implements a dual 8-bit I/O port architecture (P0_0–P0_7 and P1_0–P1_7), each with independent configuration, input, output, and polarity inversion registers. All 16 pins default to high-impedance inputs at power-up, with internal weak pull-ups enabled by default.

Its interrupt logic monitors input transitions only on pins configured as inputs and asserts the open-drain INT signal within tv(INT) after any change-reset upon reading the corresponding input register or when pin state reverts. The device uses a synchronous I²C state machine with internal power-on reset (VPORR/VPORF thresholds) and supports up to eight devices on one bus via A0–A2 address pins.

Key Specifications

Pinout & Package

HWQFN24 (SOT8041-1), 4 mm × 4 mm × 0.75 mm, thermally enhanced, no leads, 0.5 mm pitch. Exposed thermal pad must be soldered to PCB ground plane with thermal vias for reliable operation above 50 °C ambient.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TCA6424A and PCA9555, the NCA9555BYHP delivers lower quiescent current, integrated polarity inversion, and certified CDM ESD protection - making it optimal for battery-powered and safety-critical industrial designs where register determinism and long-term reliability are non-negotiable.

Availability

NCA9555BYHP is available at Aetrix Electronics and suitable for industrial sensor hubs, ACPI power switch interfaces, LED matrix drivers, and keypad scanners requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for NCA9555BYHP 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

Nexperia is a global semiconductor expert focused on essential efficiency technologies, delivering high-performance, high-reliability components for automotive, industrial, and consumer markets.

The NCA9555 series targets space-constrained embedded systems needing scalable, interrupt-driven I/O expansion with minimal firmware overhead - emphasizing deterministic power-up behavior and robust I²C interoperability.

FAQ

What is the maximum sink current per I/O pin on the NCA9555BYHP?

The NCA9555BYHP supports up to 25 mA sink current per I/O pin in output mode, verified under continuous DC conditions at TA = 85 °C and VCC = 3.3 V. This rating applies to both P0 and P1 ports and is limited by thermal dissipation in the HWQFN24 package - derating is required above 60 °C ambient unless thermal vias and copper pour are implemented.

Can the NCA9555BYHP operate with a 1.8 V microcontroller I²C bus?

Yes - the NCA9555BYHP supports I²C operation down to 1.65 V VCC and features 5 V tolerant SDA/SCL pins. When powered at 1.8 V, its I²C interface fully complies with standard-mode timing (100 kHz) and Fast-mode (400 kHz) specifications, including rise/fall time and noise margin requirements, without external level shifters.

How does the interrupt output behave when multiple input pins change simultaneously?

The INT pin asserts on the first detected input transition and remains active until the host reads the corresponding input port register - even if additional changes occur during assertion. Subsequent transitions before register read do not extend the pulse width but are captured in the input register; the interrupt clears only upon read acknowledgment (ACK/NACK), ensuring no event loss in burst scenarios.

Is the exposed thermal pad on the HWQFN24 package electrically connected to GND?

Yes - the exposed pad on the NCA9555BYHP's HWQFN24 package is internally bonded to the die substrate and must be soldered to the PCB's GND plane. Per Nexperia's SOT8041-1 mechanical specification, this connection is mandatory for electrical stability, thermal performance, and ESD path integrity; omitting it risks latch-up and premature failure above 60 °C ambient.