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NXP Semiconductors PCA8574D,518 — Logic ICs

NXP PCA8574D,518 I2C 8-bit I/O Expander, 400 kHz, 16-SOIC

MPNPCA8574D,518
End of Life

NXP PCA8574D,518 I2C 8-bit I/O expander, 400 kHz clock, push-pull outputs, POR, 2.3V–5.5V supply, -40°C to 85°C, 16-SOIC package.

$1.79Ref. price · indicative, final on quote
NXP Semiconductors PCA8574D,518 datasheet (PDF)
Packaging16-SOIC (0.295", 7.50mm Width)
RoHSROHS3 Compliant
Sourced new & surplus through independent channelsAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

PCA8574D,518 specifications
ParameterValue
Output typePush-Pull
MountingSurface Mount
Voltage2.3V ~ 5.5V
Current - output source (Sink)100µA, 25mA
Frequency400 kHz
InterfaceI2C
Operating temperature-40°C ~ 85°C
PackageTape & Reel (TR); Cut Tape (CT)
FeaturesPOR
Number of i (O)8
Case16-SOIC (0.295\", 7.50mm Width)
Interrupt outputYes

Product details

What this I²C expander does that a direct GPIO port cannot

The NXP PCA8574D,518 is an 8-bit I/O expander that communicates over the I²C bus at up to 400 kHz, adding eight push-pull digital I/O lines to any host controller that has an I²C interface. It includes a power-on reset (POR) feature that ensures the outputs start in a known state after power-up, avoiding the glitches that can happen when a microcontroller's GPIOs are still initialising.

I/O drive and load considerations

Each I/O pin can sink up to 25 mA and source only 100 µA. If you need to drive a load that requires sourcing current — like a P-channel MOSFET gate or a high-side switch — you will need an external pull-up resistor or a different expander architecture.

The supplier device package is 16-SO. The 1.27 mm pin pitch is compatible with most SOIC footprints, but the wider body means it will not fit a narrow (3.9 mm) SOIC land pattern — double-check the PCB layout before committing.

NXP lists the PCA8574D,518 as Active in production, and it is ROHS3 compliant.

Frequently asked questions

Can PCA8574D replace PCF8574?

The PCA8574D is a direct drop-in replacement for the PCF8574 in most designs. Both are 8-bit I²C I/O expanders in the same 16-SOIC package with the same pinout and I²C address map. The PCA8574D adds a power-on reset feature that the PCF8574 lacks, which ensures known output states at startup. Functionally they are interchangeable, but if your design depends on the PCF8574's specific power-up behaviour (outputs float high), test the PCA8574D's POR behaviour first.

Is PCA8574D compatible with 5V logic?

Yes. The I²C interface and I/O pins are 5 V-tolerant when powered at 5 V, and the push-pull outputs swing rail-to-rail, so they drive 5 V CMOS inputs directly.