PCF8574TS/3,112 - NXP Semiconductors / Philips Semiconductors

DATA SH EET

Product speciﬁcation

Supersedes data of 2002 Jul 29 2002 Nov 22

INTEGRATED CIRCUITS

PCF8574

Remote 8-bit I/O expander for

I2C-bus

2002 Nov 22 2

Philips Semiconductors Product speciﬁcation

Remote 8-bit I/O expander for I2C-bus PCF8574

CONTENTS

1 FEATURES

2 GENERAL DESCRIPTION

3 ORDERING INFORMATION

4 BLOCK DIAGRAM

5 PINNING

5.1 DIP16 and SO16 packages

5.2 SSOP20 package

6 CHARACTERISTICS OF THE I2C-BUS

6.1 Bit transfer

6.2 Start and stop conditions

6.3 System configuration

6.4 Acknowledge

7 FUNCTIONAL DESCRIPTION

7.1 Addressing

7.2 Interrupt output

7.3 Quasi-bidirectional I/Os

8 LIMITING VALUES

9 HANDLING

10 DC CHARACTERISTICS

11 I2C-BUS TIMING CHARACTERISTICS

12 PACKAGE OUTLINES

13 SOLDERING

13.1 Introduction

13.2 Through-hole mount packages

13.2.1 Soldering by dipping or by solder wave

13.2.2 Manual soldering

13.3 Surface mount packages

13.3.1 Reflow soldering

13.3.2 Wave soldering

13.3.3 Manual soldering

13.4 Suitability of IC packages for wave, reflow and

dipping soldering methods

14 DATA SHEET STATUS

15 DEFINITIONS

16 DISCLAIMERS

17 PURCHASE OF PHILIPS I2C COMPONENTS

2002 Nov 22 3

Philips Semiconductors Product speciﬁcation

Remote 8-bit I/O expander for I2C-bus PCF8574

1 FEATURES

•Operating supply voltage 2.5 to 6 V

•Low standby current consumption of 10 µA maximum

•I2C-bus to parallel port expander

•Open-drain interrupt output

•8-bit remote I/O port for the I2C-bus

•Compatible with most microcontrollers

•Latched outputs with high current drive capability for

directly driving LEDs

•Address by 3 hardware address pins for use of up to

8 devices (up to 16 with PCF8574A)

•DIP16, or space-saving SO16 or SSOP20 packages.

2 GENERAL DESCRIPTION

ThePCF8574isasiliconCMOScircuit.Itprovidesgeneral

purpose remote I/O expansion for most microcontroller

families via the two-line bidirectional bus (I2C-bus).

The device consists of an 8-bit quasi-bidirectional port and

an I2C-bus interface. The PCF8574 has a low current

consumption and includes latched outputs with high

current drive capability for directly driving LEDs. It also

possesses an interrupt line (INT) which can be connected

to the interrupt logic of the microcontroller. By sending an

interrupt signal on this line, the remote I/O can inform the

microcontrollerifthere is incoming dataonits ports without

having to communicate via the I2C-bus. This means that

the PCF8574 can remain a simple slave device.

The PCF8574 and PCF8574A versions differ only in their

slave address as shown in Fig.10.

3 ORDERING INFORMATION

TYPE NUMBER PACKAGE

NAME DESCRIPTION VERSION

PCF8574P;

PCF8574AP DIP16 plastic dual in-line package; 16 leads (300 mil) SOT38-4

PCF8574T;

PCF8574AT SO16 plastic small outline package; 16 leads; body width 7.5 mm SOT162-1

PCF8574TS;

PCF8574ATS SSOP20 plastic shrink small outline package; 20 leads; body width 4.4 mm SOT266-1

2002 Nov 22 4

Philips Semiconductors Product speciﬁcation

Remote 8-bit I/O expander for I2C-bus PCF8574

4 BLOCK DIAGRAM

Fig.1 Block diagram (pin numbers apply to DIP16 and SO16 packages).

handbook, full pagewidth

MBD980

I C BUS

CONTROL

INPUT

FILTER

13 INTERRUPT

LOGIC

12 P7

11 P6

10 P5

9P4

7P3

6P2

5P1

4P0

8 BIT I/O

PORT

SHIFT

LP FILTER

WRITE pulse

READ pulse

POWER-ON

RESET

VDD

VSS

SDA

SCL

INT

PCF8574

2002 Nov 22 5

Philips Semiconductors Product speciﬁcation

Remote 8-bit I/O expander for I2C-bus PCF8574

5 PINNING

5.1 DIP16 and SO16 packages

SYMBOL PIN DESCRIPTION

A0 1 address input 0

A1 2 address input 1

A2 3 address input 2

P0 4 quasi-bidirectional I/O 0

P1 5 quasi-bidirectional I/O 1

P2 6 quasi-bidirectional I/O 2

P3 7 quasi-bidirectional I/O 3

VSS 8 supply ground

P4 9 quasi-bidirectional I/O 4

P5 10 quasi-bidirectional I/O 5

P6 11 quasi-bidirectional I/O 6

P7 12 quasi-bidirectional I/O 7

INT 13 interrupt output (active LOW)

SCL 14 serial clock line

SDA 15 serial data line

VDD 16 supply voltage

handbook, halfpage

INT

SDA

VSS

SCL

VDD

PCF8574P

PCF8574AP

MBD979

Fig.2 Pin configuration (DIP16).

handbook, halfpage

INT

SDA

VSS

SCL

VDD

PCF8574T

PCF8574AT

MCE001

Fig.3 Pin configuration (SO16).

2002 Nov 22 6

Philips Semiconductors Product speciﬁcation

Remote 8-bit I/O expander for I2C-bus PCF8574

5.2 SSOP20 package

SYMBOL PIN DESCRIPTION

INT 1 interrupt output (active LOW)

SCL 2 serial clock line

n.c. 3 not connected

SDA 4 serial data line

VDD 5 supply voltage

A0 6 address input 0

A1 7 address input 1

n.c. 8 not connected

A2 9 address input 2

P0 10 quasi-bidirectional I/O 0

P1 11 quasi-bidirectional I/O 1

P2 12 quasi-bidirectional I/O 2

n.c. 13 not connected

P3 14 quasi-bidirectional I/O 3

VSS 15 supply ground

P4 16 quasi-bidirectional I/O 4

P5 17 quasi-bidirectional I/O 5

n.c. 18 not connected

P6 19 quasi-bidirectional I/O 6

P7 20 quasi-bidirectional I/O 7

handbook, halfpage

INT

SCL

n.c.

SDA

VDD

n.c.

VSS

n.c.

PCF8574TS

PCF8574ATS

MBD978

Fig.4 Pin configuration (SSOP20).

2002 Nov 22 7

Philips Semiconductors Product speciﬁcation

Remote 8-bit I/O expander for I2C-bus PCF8574

6 CHARACTERISTICS OF THE I2C-BUS

The I2C-bus is for 2-way, 2-line communication between

different ICs or modules. The two lines are a serial data

line(SDA) anda serialclock line (SCL). Both lines must be

connected to a positive supply via a pull-up resistor when

connected to the output stages of a device. Data transfer

may be initiated only when the bus is not busy.

6.1 Bit transfer

One data bit is transferred during each clock pulse. The

data on the SDA line must remain stable during the HIGH

period of the clock pulse as changes in the data line at this

time will be interpreted as control signals (see Fig.5).

6.2 Start and stop conditions

Bothdata and clocklinesremain HIGHwhenthe busisnot

busy. A HIGH-to-LOW transition of the data line, while the

clock is HIGH is defined as the start condition (S).

A LOW-to-HIGH transition of the data line while the clock

is HIGH is defined as the stop condition (P) (see Fig.6).

6.3 System conﬁguration

A device generating a message is a ‘transmitter’, a device

receiving is the ‘receiver’. The device that controls the

message is the ‘master’ and the devices which are

controlled by the master are the ‘slaves’ (see Fig.7).

Fig.5 Bit transfer.

handbook, full pagewidth

MBC621

data line

stable;

data valid

change

of data

allowed

SDA

SCL

Fig.6 Definition of start and stop conditions.

handbook, full pagewidth

MBC622

SDA

SCL P

STOP condition

SDA

SCL

START condition

Fig.7 System configuration.

MBA605

MASTER

TRANSMITTER /

RECEIVER SLAVE

TRANSMITTER /

RECEIVER MASTER

TRANSMITTER MASTER

TRANSMITTER /

RECEIVER

SDA

SCL

2002 Nov 22 8

Philips Semiconductors Product speciﬁcation

Remote 8-bit I/O expander for I2C-bus PCF8574

6.4 Acknowledge

The number of data bytes transferred between the start

and the stop conditions from transmitter to receiver is not

limited. Each byte of eight bits is followed by one

acknowledge bit (see Fig.8). The acknowledge bit is a

HIGH level put on the bus by the transmitter whereas the

master generates an extra acknowledge related clock

pulse.

A slave receiver which is addressed must generate an

acknowledge after the reception of each byte. Also a

master must generate an acknowledge after the reception

of each byte that has been clocked out of the slave

transmitter. The device that acknowledges has to pull

downthe SDA line during the acknowledge clock pulse, so

that the SDA line is stable LOW during the HIGH period of

the acknowledge related clock pulse, set-up and hold

times must be taken into account.

A master receiver must signal an end of data to the

transmitter by not generating an acknowledge on the last

byte that has been clocked out of the slave. In this event

thetransmittermust leave thedataline HIGH toenablethe

master to generate a stop condition.

Fig.8 Acknowledgment on the I2C-bus.

handbook, full pagewidth

MBC602

START

condition

9821

clock pulse for

acknowledgement

not acknowledge

acknowledge

DATA OUTPUT

BY TRANSMITTER

DATA OUTPUT

BY RECEIVER

SCL FROM

MASTER

2002 Nov 22 9

Philips Semiconductors Product speciﬁcation

Remote 8-bit I/O expander for I2C-bus PCF8574

7 FUNCTIONAL DESCRIPTION

Fig.9 Simplified schematic diagram of each I/O.

handbook, full pagewidth

MBD977

100

µA

to interrupt

logic

VSS

P0 to P7

VDD

write pulse

data from

shift register

power-on

reset

read pulse

data to

shift register

7.1 Addressing

For addressing see Figs 10, 11 and 12.

Fig.10 PCF8574 and PCF8574A slave addresses.

handbook, full pagewidth

MBD973

S 0 1 0 0 A2 A1 A0 0 A 1 0

slave address slave address

S 0 1 1 A2 A1 A0

a. PCF8574. b. PCF8574A.

Each of the PCF8574’s eight I/Os can be independently used as an input or output. Input data is transferred from the

port to the microcontroller by the READ mode (see Fig.12). Output data is transmitted to the port by the WRITE mode

(see Fig.11).

This text is here in white to force landscape pages to be rotated correctly when browsing through the pdf in the Acrobat reader.This text is here in

_white to force landscape pages to be rotated correctly when browsing through the pdf in the Acrobat reader.This text is here inThis text is here in

white to force landscape pages to be rotated correctly when browsing through the pdf in the Acrobat reader. white to force landscape pages to be ...

2002 Nov 22 10

Philips Semiconductors Product speciﬁcation

Remote 8-bit I/O expander for I2C-bus PCF8574

ndbook, full pagewidth

MBD974

S 0 1 0 0 A2 A1 A0 0 A

start condition

DATA 1

R/W acknowledge

from slave

A DATA 2 ASDA

SCL

WRITE TO

PORT

tpv

DATA OUT

FROM PORT

slave address (PCF8574) data to port data to port

12345678

acknowledge

from slave acknowledge

from slave

tpv

DATA 2 VALIDDATA 1 VALID

Fig.11 WRITE mode (output).

This text is here in white to force landscape pages to be rotated correctly when browsing through the pdf in the Acrobat reader.This text is here in

_white to force landscape pages to be rotated correctly when browsing through the pdf in the Acrobat reader.This text is here inThis text is here in

white to force landscape pages to be rotated correctly when browsing through the pdf in the Acrobat reader. white to force landscape pages to be ...

2002 Nov 22 11

Philips Semiconductors Product speciﬁcation

Remote 8-bit I/O expander for I2C-bus PCF8574

handbook, full pagewidth

MBD975

S 0 1 0 0 A2 A1 A0 1 A

start condition

DATA 1

R/W acknowledge

from slave

ADATA 4 1SDA

READ FROM

PORT

tph

DATA INTO

PORT

slave address (PCF8574) data from port data from port

acknowledge

from slave stop

condition

tps

DATA 4

DATA 2 DATA 3

tir

tiv

INT

Fig.12 READ mode (input).

A LOW-to-HIGH transition of SDA, while SCL is HIGH is defined as the stop condition (P). Transfer of data can be stopped at any moment by a stop condition. When this occurs, data present

at the last acknowledge phase is valid (output mode). Input data is lost.

2002 Nov 22 12

Philips Semiconductors Product speciﬁcation

Remote 8-bit I/O expander for I2C-bus PCF8574

7.2 Interrupt output

The PCF8574 provides an open-drain output (INT) which

can be fed to a corresponding input of the microcontroller

(see Figs 13 and 14). This gives these chips a type of

master function which can initiate an action elsewhere in

the system.

Aninterruptisgenerated by anyrisingorfallingedge of the

port inputs in the input mode. After time tiv the signal INT is

valid.

Resetting and reactivating the interrupt circuit is achieved

when data on the port is changed to the original setting or

dataisreadfrom or writtentotheportwhich has generated

the interrupt.

Resetting occurs as follows:

•IntheREADmodeattheacknowledgebitaftertherising

edge of the SCL signal

•In the WRITE mode at the acknowledge bit after the

HIGH-to-LOW transition of the SCL signal

•Interrupts which occur during the acknowledge clock

pulse may be lost (or very short) due to the resetting of

the interrupt during this pulse.

Each change of the I/Os after resetting will be detected

and, after the next rising clock edge, will be transmitted as

INT. Reading from or writing to another device does not

affect the interrupt circuit.

7.3 Quasi-bidirectional I/Os

A quasi-bidirectional I/O can be used as an input or output

without the use of a control signal for data direction

(see Fig.15). At power-on the I/Os are HIGH. In this mode

only a current source to VDD is active. An additional strong

pull-up to VDD allows fast rising edges into heavily loaded

outputs. These devices turn on when an output is written

HIGH, and are switched off by the negative edge of SCL.

The I/Os should be HIGH before being used as inputs.

handbook, full pagewidth

MBD976

MICROCONTROLLER

INT INT INT

PCF8574

(1) PCF8574

(2)

VDD

INT

PCF8574

(16)

Fig.13 Application of multiple PCF8574s with interrupt.

Fig.14 Interrupt generated by a change of input to I/O P5.

handbook, full pagewidth

MBD972

S 0 1 0 0 A2 A1 A0 1 A

start condition

R/W acknowledge

from slave

1SDA

SCL

DATA INTO

tir

INT

slave address (PCF8574) data from port

12345678

stop

condition

tiv

This text is here in white to force landscape pages to be rotated correctly when browsing through the pdf in the Acrobat reader.This text is here in

_white to force landscape pages to be rotated correctly when browsing through the pdf in the Acrobat reader.This text is here inThis text is here in

white to force landscape pages to be rotated correctly when browsing through the pdf in the Acrobat reader. white to force landscape pages to be ...

2002 Nov 22 13

Philips Semiconductors Product speciﬁcation

Remote 8-bit I/O expander for I2C-bus PCF8574

handbook, full pagewidth

MBD971

S 0 1 1 1 A2 A1 A0 0 A

start condition

R/W acknowledge

from slave

A 0

A P

SDA

SCL

OUTPUT

VOLTAGE

IOHt IOH

PULL-UP

OUTPUT

CURRENT

slave address (PCF8574A) data to port data to port

12345678

Fig.15 Transient pull-up current IOHt while P3 changes from LOW-to-HIGH and back to LOW.

2002 Nov 22 14

Philips Semiconductors Product speciﬁcation

Remote 8-bit I/O expander for I2C-bus PCF8574

8 LIMITING VALUES

In accordance with the Absolute Maximum Rating System (IEC 60134).

9 HANDLING

Inputs and outputs are protected against electrostatic discharge in normal handling. However it is good practice to take

normal precautions appropriate to handling MOS devices (see

“Handling MOS devices”

10 DC CHARACTERISTICS

VDD = 2.5 to 6 V; VSS = 0 V; Tamb =−40 to +85 °C; unless otherwise speciﬁed.

SYMBOL PARAMETER MIN. MAX. UNIT

VDD supply voltage −0.5 +7.0 V

VIinput voltage VSS −0.5 VDD + 0.5 V

IIDC input current −±20 mA

IODC output current −±25 mA

IDD supply current −±100 mA

ISS supply current −±100 mA

Ptot total power dissipation −400 mW

POpower dissipation per output −100 mW

Tstg storage temperature −65 +150 °C

Tamb ambient temperature −40 +85 °C

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

Supply

VDD supply voltage 2.5 −6.0 V

IDD supply current operatingmode;VDD =6V;

no load; VI=V

DD or VSS;

fSCL = 100 kHz

−40 100 µA

Istb standby current standby mode; VDD =6V;

no load; VI=V

DD or VSS

−2.5 10 µA

VPOR Power-on reset voltage VDD = 6 V; no load;

VI=V

DD or VSS; note 1 −1.3 2.4 V

Input SCL; input/output SDA

VIL LOW level input voltage −0.5 −+0.3VDD V

VIH HIGH level input voltage 0.7VDD −VDD + 0.5 V

IOL LOW level output current VOL = 0.4 V 3 −− mA

ILleakage current VI=V

DD or VSS −1−+1 µA

Ciinput capacitance VI=V

SS −−7pF

2002 Nov 22 15

Philips Semiconductors Product speciﬁcation

Remote 8-bit I/O expander for I2C-bus PCF8574

Note

1. The Power-on reset circuit resets the I2C-bus logic at VDD <V

POR and sets all I/Os to logic 1 (with current source to

VDD).

I/Os

VIL LOW level input voltage −0.5 −+0.3VDD V

VIH HIGH level input voltage 0.7VDD −VDD + 0.5 V

IIHL(max) maximum allowed input

current through protection

diode

VI≥VDD or VI≤VSS −−±400 µA

IOL LOW level output current VOL =1V; V

DD =5V 10 25 −mA

IOH HIGH level output current VOH =V

SS 30 −300 µA

IOHt transient pull-up current HIGH during acknowledge

(see Fig.15); VOH =V

SS;

VDD = 2.5 V

−−1−mA

Ciinput capacitance −−10 pF

Cooutput capacitance −−10 pF

Port timing; CL≤100 pF (see Figs 11 and 12)

tpv output data valid −−4µs

su input data set-up time 0 −− µs

hinput data hold time 4 −− µs

Interrupt INT (see Fig.14)

IOL LOW level output current VOL = 0.4 V 1.6 −− mA

ILleakage current VI=V

DD or VSS −1−+1 µA

TIMING;C

L≤100 pF

tiv input data valid time −−4µs

ir reset delay time −−4µs

Select inputs A0 to A2

VIL LOW level input voltage −0.5 −+0.3VDD V

VIH HIGH level input voltage 0.7VDD −VDD + 0.5 V

ILI input leakage current pin at VDD or VSS −250 −+250 nA

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

2002 Nov 22 16

Philips Semiconductors Product speciﬁcation

Remote 8-bit I/O expander for I2C-bus PCF8574

11 I2C-BUS TIMING CHARACTERISTICS

Note

1. All the timing values are valid within the operating supply voltage and ambient temperature range and refer to VIL

and VIH with an input voltage swing of VSS to VDD.

SYMBOL PARAMETER MIN. TYP. MAX. UNIT

I2C-bus timing (see Fig.16; note 1)

fSCL SCL clock frequency −−100 kHz

tSW tolerable spike width on bus −−100 ns

tBUF bus free time 4.7 −−µs

SU;STA START condition set-up time 4.7 −−µs

HD;STA START condition hold time 4.0 −−µs

LOW SCL LOW time 4.7 −−µs

HIGH SCL HIGH time 4.0 −−µs

rSCL and SDA rise time −−1.0 µs

tfSCL and SDA fall time −−0.3 µs

tSU;DAT data set-up time 250 −−ns

tHD;DAT data hold time 0 −−ns

tVD;DAT SCL LOW to data out valid −−3.4 µs

tSU;STO STOP condition set-up time 4.0 −−µs

Fig.16 I2C-bus timing diagram.

handbook, full pagewidth

PROTOCOL

SCL

SDA

MBD820

BIT 0

LSB

(R/W)

tHD;STA tSU;DAT tHD;DAT tVD;DAT tSU;STO

tBUF

tSU;STA tLOW tHIGH 1 / fSCL

START

CONDITION

(S)

BIT 7

MSB

(A7)

BIT 6

(A6) ACKNOWLEDGE

(A) STOP

CONDITION

(P)

2002 Nov 22 17

Philips Semiconductors Product speciﬁcation

Remote 8-bit I/O expander for I2C-bus PCF8574

12 PACKAGE OUTLINES

REFERENCES

OUTLINE

VERSION EUROPEAN

PROJECTION ISSUE DATE

IEC JEDEC EIAJ

SOT38-4 92-11-17

95-01-14

(e )

seating plane

pin 1 index

0 5 10 mm

scale

Note

1. Plastic or metal protrusions of 0.25 mm maximum per side are not included.

UNIT A

max. 12 b

1(1) (1) (1)

b2cD E e M Z

DIMENSIONS (inch dimensions are derived from the original mm dimensions)

min. A

max. bmax.

1.73

1.30 0.53

0.38 0.36

0.23 19.50

18.55 6.48

6.20 3.60

3.05 0.2542.54 7.62 8.25

7.80 10.0

8.3 0.764.2 0.51 3.2

inches 0.068

0.051 0.021

0.015 0.014

0.009

1.25

0.85

0.049

0.033 0.77

0.73 0.26

0.24 0.14

0.12 0.010.10 0.30 0.32

0.31 0.39

0.33 0.0300.17 0.020 0.13

DIP16: plastic dual in-line package; 16 leads (300 mil) SOT38-4

2002 Nov 22 18

Philips Semiconductors Product speciﬁcation

Remote 8-bit I/O expander for I2C-bus PCF8574

UNIT A

max. A1A2A3bpcD

(1) E(1) (1)

ELL

pQZ

ywv θ

REFERENCES

OUTLINE

VERSION EUROPEAN

PROJECTION ISSUE DATE

IEC JEDEC EIAJ

inches

2.65 0.30

0.10 2.45

2.25 0.49

0.36 0.32

0.23 10.5

10.1 7.6

7.4 1.27 10.65

10.00 1.1

1.0 0.9

0.4 8

0.25 0.1

DIMENSIONS (inch dimensions are derived from the original mm dimensions)

Note

1. Plastic or metal protrusions of 0.15 mm maximum per side are not included.

1.1

0.4

SOT162-1

detail X

0.25

075E03 MS-013

pin 1 index

0.10 0.012

0.004 0.096

0.089 0.019

0.014 0.013

0.009 0.41

0.40 0.30

0.29 0.050

1.4

0.055

0.419

0.394 0.043

0.039 0.035

0.016

0.01

0.25

0.01 0.004

0.043

0.016

0.01

vMA

(A )

0 5 10 mm

scale

SO16: plastic small outline package; 16 leads; body width 7.5 mm SOT162-1

97-05-22

99-12-27

2002 Nov 22 19

Philips Semiconductors Product speciﬁcation

Remote 8-bit I/O expander for I2C-bus PCF8574

UNIT A1A2A3bpcD

(1) E(1) (1)

ELL

pQZywv θ

REFERENCES

OUTLINE

VERSION EUROPEAN

PROJECTION ISSUE DATE

IEC JEDEC EIAJ

mm 0.15

01.4

1.2 0.32

0.20 0.20

0.13 6.6

6.4 4.5

4.3 0.65 1.0 0.2

6.6

6.2 0.65

0.45 0.48

0.18 10

0.13 0.1

DIMENSIONS (mm are the original dimensions)

Note

1. Plastic or metal protrusions of 0.20 mm maximum per side are not included.

0.75

0.45

SOT266-1 MO-152 95-02-22

99-12-27

detail X

vMA

(A )

0.25

110

20 11

pin 1 index

0 2.5 5 mm

scale

SSOP20: plastic shrink small outline package; 20 leads; body width 4.4 mm SOT266-1

max.

1.5

2002 Nov 22 20

Philips Semiconductors Product speciﬁcation

Remote 8-bit I/O expander for I2C-bus PCF8574

13 SOLDERING

13.1 Introduction

Thistextgivesaverybriefinsight to a complextechnology.

A more in-depth account of soldering ICs can be found in

our

“Data Handbook IC26; Integrated Circuit Packages”

(document order number 9398 652 90011).

There is no soldering method that is ideal for all IC

packages. Wave soldering is often preferred when

through-holeandsurfacemountcomponentsaremixedon

one printed-circuit board. Wave soldering can still be used

for certain surface mount ICs, but it is not suitable for fine

pitch SMDs. In these situations reflow soldering is

recommended.

13.2 Through-hole mount packages

13.2.1 SOLDERING BY DIPPING OR BY SOLDER WAVE

The maximum permissible temperature of the solder is

260 °C; solder at this temperature must not be in contact

with the joints for more than 5 seconds. The total contact

time of successive solder waves must not exceed

5 seconds.

The device may be mounted up to the seating plane, but

the temperature of the plastic body must not exceed the

specified maximum storage temperature (Tstg(max)). If the

printed-circuit board has been pre-heated, forced cooling

may be necessary immediately after soldering to keep the

temperature within the permissible limit.

13.2.2 MANUAL SOLDERING

Apply the soldering iron (24 V or less) to the lead(s) of the

package, either below the seating plane or not more than

2 mm above it. If the temperature of the soldering iron bit

is less than 300 °C it may remain in contact for up to

10 seconds. If the bit temperature is between

300 and 400 °C, contact may be up to 5 seconds.

13.3 Surface mount packages

13.3.1 REFLOW SOLDERING

Reflow soldering requires solder paste (a suspension of

fine solder particles, flux and binding agent) to be applied

tothe printed-circuit boardbyscreen printing,stencillingor

pressure-syringe dispensing before package placement.

Several methods exist for reflowing; for example,

convection or convection/infrared heating in a conveyor

type oven. Throughput times (preheating, soldering and

cooling) vary between 100 and 200 seconds depending

on heating method.

Typical reflow peak temperatures range from

215 to 250 °C. The top-surface temperature of the

packages should preferable be kept below 220 °C for

thick/large packages, and below 235 °C for small/thin

packages.

13.3.2 WAVE SOLDERING

Conventional single wave soldering is not recommended

forsurfacemountdevices(SMDs)orprinted-circuitboards

with a high component density, as solder bridging and

non-wetting can present major problems.

To overcome these problems the double-wave soldering

method was specifically developed.

If wave soldering is used the following conditions must be

observed for optimal results:

•Use a double-wave soldering method comprising a

turbulent wave with high upward pressure followed by a

smooth laminar wave.

•For packages with leads on two sides and a pitch (e):

– larger than or equal to 1.27 mm, the footprint

longitudinal axis is preferred to be parallel to the

transport direction of the printed-circuit board;

– smaller than 1.27 mm, the footprint longitudinal axis

must be parallel to the transport direction of the

printed-circuit board.

The footprint must incorporate solder thieves at the

downstream end.

•Forpackageswithleadsonfoursides,thefootprintmust

be placed at a 45°angle to the transport direction of the

printed-circuit board. The footprint must incorporate

solder thieves downstream and at the side corners.

During placement and before soldering, the package must

be fixed with a droplet of adhesive. The adhesive can be

applied by screen printing, pin transfer or syringe

dispensing. The package can be soldered after the

adhesive is cured.

Typical dwell time is 4 seconds at 250 °C.

A mildly-activated flux will eliminate the need for removal

of corrosive residues in most applications.

13.3.3 MANUAL SOLDERING

Fix the component by first soldering two

diagonally-opposite end leads. Use a low voltage (24 V or

less) soldering iron applied to the flat part of the lead.

Contact time must be limited to 10 seconds at up to

300 °C. When using a dedicated tool, all other leads can

be soldered in one operation within 2 to 5 seconds

between 270 and 320 °C.

2002 Nov 22 21

Philips Semiconductors Product speciﬁcation

Remote 8-bit I/O expander for I2C-bus PCF8574

13.4 Suitability of IC packages for wave, reﬂow and dipping soldering methods

Notes

1. Formoredetailed information ontheBGA packages referto the

“(LF)BGAApplication Note

”(AN01026);order a copy

from your Philips Semiconductors sales office.

2. All surface mount (SMD) packages are moisture sensitive. Depending upon the moisture content, the maximum

temperature (with respect to time) and body size of the package, there is a risk that internal or external package

cracks may occur due to vaporization of the moisture in them (the so called popcorn effect). For details, refer to the

Drypack information in the

“Data Handbook IC26; Integrated Circuit Packages; Section: Packing Methods”

3. For SDIP packages, the longitudinal axis must be parallel to the transport direction of the printed-circuit board.

4. These packages are not suitable for wave soldering. On versions with the heatsink on the bottom side, the solder

cannot penetrate between the printed-circuit board and the heatsink. On versions with the heatsink on the top side,

the solder might be deposited on the heatsink surface.

5. If wave soldering is considered, then the package must be placed at a 45° angle to the solder wave direction.

The package footprint must incorporate solder thieves downstream and at the side corners.

6. Wave soldering is suitable for LQFP, QFP and TQFP packages with a pitch (e) larger than 0.8 mm; it is definitely not

suitable for packages with a pitch (e) equal to or smaller than 0.65 mm.

7. Wave soldering is suitable for SSOP and TSSOP packages with a pitch (e) equal to or larger than 0.65 mm; it is

definitely not suitable for packages with a pitch (e) equal to or smaller than 0.5 mm.

MOUNTING PACKAGE(1) SOLDERING METHOD

WAVE REFLOW(2) DIPPING

Through-hole mount DBS, DIP, HDIP, SDIP, SIL suitable(3) −suitable

Surface mount BGA, LBGA, LFBGA, SQFP, TFBGA, VFBGA not suitable suitable −

HBCC, HBGA, HLQFP, HSQFP, HSOP,

HTQFP, HTSSOP, HVQFN, HVSON, SMS not suitable(4) suitable −

PLCC(5), SO, SOJ suitable suitable −

LQFP, QFP, TQFP not recommended(5)(6) suitable −

SSOP, TSSOP, VSO not recommended(7) suitable −

2002 Nov 22 22

Philips Semiconductors Product speciﬁcation

Remote 8-bit I/O expander for I2C-bus PCF8574

14 DATA SHEET STATUS

Notes

1. Please consult the most recently issued data sheet before initiating or completing a design.

2. The product status of the device(s) described in this data sheet may have changed since this data sheet was

published. The latest information is available on the Internet at URL http://www.semiconductors.philips.com.

3. For data sheets describing multiple type numbers, the highest-level product status determines the data sheet status.

LEVEL DATA SHEET

STATUS(1) PRODUCT

STATUS(2)(3) DEFINITION

I Objective data Development This data sheet contains data from the objective speciﬁcation for product

development. Philips Semiconductors reserves the right to change the

speciﬁcation in any manner without notice.

II Preliminary data Qualiﬁcation This data sheet contains data from the preliminary speciﬁcation.

Supplementary data will be published at a later date. Philips

Semiconductors reserves the right to change the speciﬁcation without

notice, in order to improve the design and supply the best possible

product.

III Product data Production This data sheet contains data from the product speciﬁcation. Philips

Semiconductors reserves the right to make changes at any time in order

to improve the design, manufacturing and supply. Relevant changes will

be communicated via a Customer Product/Process Change Notiﬁcation

(CPCN).

15 DEFINITIONS

Short-form specification  The data in a short-form

specification is extracted from a full data sheet with the

same type number and title. For detailed information see

the relevant data sheet or data handbook.

Limiting values definition Limiting values given are in

accordance with the Absolute Maximum Rating System

(IEC 60134). Stress above one or more of the limiting

values may cause permanent damage to the device.

These are stress ratings only and operation of the device

attheseorat any other conditionsabovethosegiven in the

Characteristics sections of the specification is not implied.

Exposure to limiting values for extended periods may

affect device reliability.

Application information  Applications that are

described herein for any of these products are for

illustrative purposes only. Philips Semiconductors make

norepresentationor warranty thatsuchapplicationswillbe

suitable for the specified use without further testing or

modification.

16 DISCLAIMERS

Life support applications  These products are not

designed for use in life support appliances, devices, or

systems where malfunction of these products can

reasonably be expected to result in personal injury. Philips

Semiconductorscustomersusing orsellingtheseproducts

for use in such applications do so at their own risk and

agree to fully indemnify Philips Semiconductors for any

damages resulting from such application.

Right to make changes  Philips Semiconductors

reserves the right to make changes in the products -

including circuits, standard cells, and/or software -

described or contained herein in order to improve design

and/or performance. When the product is in full production

(status ‘Production’), relevant changes will be

communicated via a Customer Product/Process Change

Notification (CPCN). Philips Semiconductors assumes no

responsibility or liability for the use of any of these

products, conveys no licence or title under any patent,

makes no representations or warranties that these

products are free from patent, copyright, or mask work

right infringement, unless otherwise specified.

2002 Nov 22 23

Philips Semiconductors Product speciﬁcation

Remote 8-bit I/O expander for I2C-bus PCF8574

17 PURCHASE OF PHILIPS I2C COMPONENTS

Purchase of Philips I2C components conveys a license under the Philips’ I2C patent to use the

components in the I2C system provided the system conforms to the I2C specification defined by

Philips. This specification can be ordered using the code 9398 393 40011.

All rights are reserved. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner.

The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed

without notice. No liability will be accepted by the publisher for any consequence of its use. Publication thereof does not convey nor imply any license

under patent- or other industrial or intellectual property rights.

Philips Semiconductors – a world wide company

Contact information

For additional information please visit http://www.semiconductors.philips.com. Fax: +31 40 27 24825

For sales ofﬁces addresses send e-mail to: sales.addresses@www.semiconductors.philips.com.

Printed in The Netherlands 403512/04/pp24 Date of release: 2002 Nov 22 Document order number: 9397 750 10462