NXP Semiconductors PCA9574HR,115

Overview

PCA9574HR,115 from NXP Semiconductors is an 8-bit I²C-bus and SMBus GPIO expander with dual supply rails (VDD = 1.1–3.6 V, VDD(IO) = 1.1–3.6 V), active-low reset and open-drain interrupt output, designed for voltage-level translation in battery-powered mobile devices such as clamshell phones and media players. It defaults all eight I/Os to inputs at power-up, supports 400 kHz I²C operation, and delivers <1 μA standby current.

For engineers reviewing the PCA9574HR,115 datasheet, PCA9574HR,115 pinout, PCA9574HR,115 application, or PCA9574HR,115 equivalent, key selection considerations include its dual-rail level-shifting capability, programmable bus-hold or 100 kΩ pull-up/pull-down per I/O, interrupt masking, polarity inversion register, and support for GPIO All Call addressing across multiple devices on one bus.

Technical Context

The PCA9574HR,115 implements a register-mapped I²C slave interface with seven user-accessible registers (Input, Polarity Inversion, Bus-Hold Enable, Pull-Up/Pull-Down Selector, Configuration, Output, Interrupt Mask, and Interrupt Status), enabling independent direction control, input state monitoring, and interrupt generation on unmasked input transitions. Its internal Power-On Reset and dedicated active-low RESET pin ensure deterministic initialization of all registers and I/O states.

It uses separate core logic (VDD) and I/O bank (VDD(IO)) supplies to enable bidirectional voltage translation between incompatible logic domains - e.g., 1.8 V controller interfacing to 3.3 V sensors - while maintaining full I²C compliance at Standard-mode (100 kHz) and Fast-mode (400 kHz). The INT pin asserts low on any unmasked input edge and clears only upon reading the Input Port register.

Key Specifications

Pinout & Package

PCA9574HR,115 is packaged in HVQFN16 (3 × 3 × 0.85 mm, no leads, exposed thermal pad), optimized for space-constrained portable designs. Pin mapping matches the PCA9574BS variant per NXP SOT758-1 specification.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit I²C GPIO expander applications.

Compared with TCA6408A and PCA9538, PCA9574HR,115 uniquely supports true bidirectional voltage translation, per-pin bus-hold or pull-up/pull-down selection, and polarity inversion - making it the only option among the three suitable for mixed-voltage, ultra-low-power, and noise-prone portable designs.

Availability

PCA9574HR,115 is available at Aetrix Electronics and suitable for battery-powered mobile gadgets, multi-voltage sensor interfaces, and industrial control systems requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for PCA9574HR,115 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 company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and consumer applications.

The PCA9574 product line was developed to extend NXP's I²C-bus I/O expander family with enhanced low-voltage operation, dual-rail level translation, and reduced standby current - specifically targeting power-sensitive mobile and portable electronics.

FAQ

What voltage levels can PCA9574HR,115 translate between?

The PCA9574HR,115 supports independent supply rails: VDD (core logic) from 1.1 V to 3.6 V and VDD(IO) (I/O bank) from 1.1 V to 3.6 V. This enables bidirectional level translation - for example, a 1.2 V microcontroller communicating with 3.3 V sensors - without external level shifters. Both rails must be within spec; operation outside this range is not guaranteed.

Does PCA9574HR,115 support interrupt debouncing in hardware?

No, the PCA9574HR,115 does not include hardware debouncing. Its INT pin asserts immediately on any unmasked input state transition. Debouncing must be implemented in firmware (e.g., by reading the Input Port register and verifying stable state over time) or externally via RC filters on input lines. The interrupt mask register (MSK) helps suppress spurious edges from noisy sources.

How many PCA9574HR,115 devices can share one I²C bus?

Up to two PCA9574HR,115 devices can operate on the same I²C bus using the A0 address pin to select between target addresses 40h and 42h. For more than two units, external I²C multiplexers (e.g., PCA9548A) or alternative expanders with additional address bits (e.g., PCA9575) are required - the PCA9574HR,115 itself has no provision for >2 devices per bus.

Can PCA9574HR,115 drive LEDs directly?

No, PCA9574HR,115 I/O pins are not rated for direct LED driving. Its output sink capability is 3 mA per pin (totem-pole), insufficient for typical indicator LEDs (often requiring 5–20 mA). It can, however, control LED driver transistors or MOSFETs - using P0–P7 as logic-level switches - while relying on external circuitry for current amplification and voltage matching.

Is the exposed thermal pad on PCA9574HR,115's HVQFN16 package electrically connected?

Yes, the exposed center pad on the PCA9574HR,115 HVQFN16 package is internally connected to VSS (ground). Per NXP SOT758-1, it must be soldered to the PCB ground plane using thermal vias for proper electrical performance, thermal dissipation, and mechanical reliability. Leaving it floating or unconnected violates the device's specified operating conditions and may cause instability or premature failure.