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PCF8574/74A: Remote 8-bit I/O expander for I²C‑bus with interrupt

The PCF8574/74A 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, 100 kHz I²C‑bus interface, three hardware address inputs and interrupt output operating between 2.5 V and 6 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. System master can read from the input port or write to the output port through a single register.

The low current consumption of 2.5 μA (typical, static) is great for mobile applications and the latched output ports directly drive LEDs.

The PCF8574 and PCF8574A 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 PCF8574/74A 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.

PCF8574_74A: Product Block Diagram

Outline 3d SOT162-1

Data Sheets (1)

Application Notes (7)

Users Guides (4)

Brochures (5)

Package Information (2)

Packing (3)

Reports or Presentations (1)

Supporting Information (3)

IBIS Model

• PCF8574AT IBIS Model (REV 1.0) ibs PCF8574AT 2/28/2013
• PCF8574T IBIS Model (REV 1.0) ibs PCF8574T 2/28/2013

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	MSL	MSL LF
PCF8574AT/3		SOT162-1	SO-SOJ-REFLOW SO-SOJ-WAVE SO-SOJ-REFLOW SO-SOJ-WAVE	Tube in Drypack	Active	PCF8574AT/3,512 (9352 755 81512)	PCF8574AT	PCF8574AT/3		week 35, 2004	2	2
				Reel 13" Q1/T1 in Drypack	Active	PCF8574AT/3,518 (9352 755 81518)	PCF8574AT	PCF8574AT/3		week 35, 2004	2	2
PCF8574TS/3		SOT266-1	SSOP-TSSOP-VSO-WAVE	Reel 13" Q1/T1	Active	PCF8574TS/3,118 (9352 756 72118)	8574TS	PCF8574TS/3		Always Pb-free	1	1
				Bulk Pack	Active	PCF8574TS/3,112 (9352 756 72112)	8574TS	PCF8574TS/3		Always Pb-free	1	1
PCF8574ATS/3		SOT266-1	SSOP-TSSOP-VSO-WAVE	Reel 13" Q1/T1	Active	PCF8574ATS/3,118 (9352 765 44118)	8574A	PCF8574ATS/3		Always Pb-free	1	1
PCF8574T/3		SOT162-1	SO-SOJ-REFLOW SO-SOJ-WAVE SO-SOJ-REFLOW SO-SOJ-WAVE	Tube in Drypack	Active	PCF8574T/3,512 (9352 756 17512)	PCF8574T	PCF8574T/3		Always Pb-free	1	2
				Reel 13" Q1/T1 in Drypack	Active	PCF8574T/3,518 (9352 756 17518)	PCF8574T	PCF8574T/3		Always Pb-free	1	2