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Texas Instruments PCF8574APWG4 — Interface & Transceivers

TI PCF8574APWG4 I²C I/O Expander, 8-Bit, 100 kHz, 20-TSSOP

MPNPCF8574APWG4
End of Life

Texas Instruments PCF8574APWG4, 8-bit I²C I/O expander, 100 kHz clock, 2.5V to 6V supply, push-pull outputs, interrupt output, 20-TSSOP package, -40°C to 85°C operating temperature.

Texas Instruments PCF8574APWG4 datasheet (PDF)
Independent supplier — new & surplus stockAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

PCF8574APWG4 specifications
ParameterValue
Output typePush-Pull
MountingSurface Mount
Supply voltage2.5V ~ 6V
Current - output source (Sink)1mA, 25mA
Clock frequency100 kHz
InterfaceI²C
Operating temperature-40°C~85°C
PackageTube
FeaturesPOR
Number of i (O)8
Case20-TSSOP (0.173\", 4.40mm Width)
Interrupt outputYes

Product details

8-bit I²C I/O expander with a wide supply window

It operates from a 2.5V to 6V supply, making it equally at home on a 3.3V MCU rail or a 5V legacy bus. The interrupt output (INT) signals the host when an input changes, saving the host from polling the bus — useful in low-power or latency-sensitive designs.

The 2.5V to 6V supply range is the headline fit parameter. At 3.3V the part is fully 3.3V-logic compatible; at 5V it works with 5V logic without level shifting. This eliminates a common BOM headache when bridging a 3.3V MCU to a 5V peripheral bus. The output sink current is 25 mA per pin, enough to drive a standard LED or a small relay coil directly (through a series resistor). Source current is limited to 1 mA, so sourcing loads need a pull-up or a buffer.

Frequently asked questions

Is PCF8574APWG4 compatible with 3.3V logic?

Yes. With a supply range of 2.5V to 6V, the part operates at 3.3V and its I²C and I/O pins are 3.3V-logic compatible. At 3.3V supply, the input thresholds meet standard 3.3V CMOS levels.

Is PCF8574APWG4 compatible with 5V?

Yes. The 2.5V to 6V supply range includes 5V operation. At 5V supply, the I/O pins are 5V-logic compatible, and the I²C bus can be pulled up to 5V as long as the host controller also operates at 5V or uses level translation.

What is the difference between PCF8574 and PCF8574A?

The PCF8574 and PCF8574A are functionally identical 8-bit I²C I/O expanders. The difference is the I²C slave address range: the PCF8574 uses addresses 0x20–0x27, while the PCF8574A uses 0x38–0x3F. This allows up to 16 of these expanders on the same I²C bus (eight of each type).