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PCA8574/74A: Remote 8-bit I/O expander for I²C-bus with interrupt

The PCA8574/74A provides general-purpose remote I/O expansion via the two-wire bidirectional I²C‑bus (serial clock (SCL), serial data (SDA)).

The devices consist of eight quasi-bidirectional ports, 400 kHz I²C‑bus interface, three hardware address inputs and interrupt output operating between 2.3 V and 5.5 V. The quasi-bidirectional port can be independently assigned as an input to monitor interrupt status or keypads, or as an output to activate indicator devices such as LEDs. The system master can read from the input port or write to the output port through a single register.

The low current consumption of 4.5 μA (typical, static) is great for mobile applications and the latched output ports have 25 mA high current sink drive capability for directly driving LEDs.

The PCA8574 and PCA8574A are identical, except for the different fixed portion of the slave address. The three hardware address pins allow eight of each device to be on the same I²C‑bus, so there can be up to 16 of these I/O expanders PCA8574/74A together on the same I²C‑bus, supporting up to 128 I/Os (for example, 128 LEDs).

The active LOW open-drain interrupt output (INT) can be connected to the interrupt logic of the microcontroller and is activated when any input state differs from its corresponding input port register state. It is used to indicate to the microcontroller that an input state has changed and the device needs to be interrogated without the microcontroller continuously polling the input register via the I²C‑bus.

The internal Power-On Reset (POR) initializes the I/Os as inputs with a weak internal pull-up 100 μA current source.

PCA8574_74A: Product Block Diagram

PCA8574_74A: Block Diagram

Outline 3d SOT403-1

Data Sheets (1)

Application Notes (2)

Users Guides (4)

Brochures (3)

Package Information (3)

Packing (3)

Supporting Information (3)

Ordering Information

Package Information

Product ID	Package Description	Outline Version	Reflow/Wave Soldering	Packing	Product Status	Part NumberOrdering code(12NC)	Marking	Chemical Content	RoHS / Pb Free / RHF	LeadFree Conversion Date	EFR	IFR(FIT)	MTBF(hour)	MSL	MSL LF
PCA8574AD		SOT162-1	SO-SOJ-REFLOW SO-SOJ-WAVE SO-SOJ-REFLOW SO-SOJ-WAVE	Tube in Drypack	Active	PCA8574AD,512 (9352 834 89512)	PCA8574AD	PCA8574AD		Always Pb-free	0.0	2.0	5E8	1	2
				Reel 13" Q1/T1 in Drypack	Active	PCA8574AD,518 (9352 834 89518)	PCA8574AD	PCA8574AD		Always Pb-free	0.0	2.0	5E8	1	2
PCA8574PW		SOT403-1	SSOP-TSSOP-VSO-WAVE	Reel 13" Q1/T1	Active	PCA8574PW,118 (9352 837 61118)	PCA8574	PCA8574PW		Always Pb-free	0.0	2.0	5E8	1	1
				Bulk Pack	Active	PCA8574PW,112 (9352 837 61112)	PCA8574	PCA8574PW		Always Pb-free	0.0	2.0	5E8	1	1
PCA8574D		SOT162-1	SO-SOJ-REFLOW SO-SOJ-WAVE SO-SOJ-REFLOW SO-SOJ-WAVE	Reel 13" Q1/T1 in Drypack	Active	PCA8574D,518 (9352 834 85518)	PCA8574D	PCA8574D		Always Pb-free	0.0	2.0	5E8	1	2
				Tube in Drypack	Active	PCA8574D,512 (9352 834 85512)	PCA8574D	PCA8574D		Always Pb-free	0.0	2.0	5E8	1	2
PCA8574APW		SOT403-1	SSOP-TSSOP-VSO-WAVE	Bulk Pack	Active	PCA8574APW,112 (9352 837 59112)	PA8574A	PCA8574APW		Always Pb-free	0.0	2.0	5E8	1	1
				Reel 13" Q1/T1	Active	PCA8574APW,118 (9352 837 59118)	PA8574A	PCA8574APW		Always Pb-free	0.0	2.0	5E8	1	1
PCA8574ATS		SOT266-1	SSOP-TSSOP-VSO-WAVE	Reel 13" Q1/T1	Active	PCA8574ATS,118 (9352 834 91118)	PA8574A	PCA8574ATS		Always Pb-free	0.0	2.0	5E8	1	1
				Bulk Pack	Active	PCA8574ATS,112 (9352 834 91112)	PA8574A	PCA8574ATS		Always Pb-free	0.0	2.0	5E8	1	1
PCA8574TS		SOT266-1	SSOP-TSSOP-VSO-WAVE	Reel 13" Q1/T1	Active	PCA8574TS,118 (9352 834 87118)	PCA8574	PCA8574TS		Always Pb-free	0.0	2.0	5E8	1	1
				Bulk Pack	Active	PCA8574TS,112 (9352 834 87112)	PCA8574	PCA8574TS		Always Pb-free	0.0	2.0	5E8	1	1