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
2
INPUT
FILTER
1
2
3
14
15
13 INTERRUPT
LOGIC
12 P7
11 P6
10 P5
9P4
7P3
6P2
5P1
4P0
8 BIT I/O
PORT
SHIFT
REGISTER
LP FILTER
WRITE pulse
READ pulse
POWER-ON
RESET
16
8
VDD
VSS
SDA
SCL
A2
A1
A0
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
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
INT
A0
A1
A2
P0
P1
P2
P3
SDA
VSS
SCL
P7
P6
P5
P4
VDD
PCF8574P
PCF8574AP
MBD979
Fig.2 Pin configuration (DIP16).
handbook, halfpage
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
INT
A0
A1
A2
P0
P1
P2
P3
SDA
VSS
SCL
P7
P6
P5
P4
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
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
INT
SCL
n.c.
SDA
VDD
A0
A1
n.c.
A2
P0
P7
P6
n.c.
P5
VSS
P4
P3
n.c.
P2
P1
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
S
START condition
Fig.7 System configuration.
MBA605
MASTER
TRANSMITTER /
RECEIVER SLAVE
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
S
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
DQ
C
I
S
FF
DQ
C
I
S
FF
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
A
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).
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2002 Nov 22 10
Philips Semiconductors Product specification
Remote 8-bit I/O expander for I2C-bus PCF8574
a
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).
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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
P
DATA 2 DATA 3
tir
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
1
P5
R/W acknowledge
from slave
1SDA
SCL
DATA INTO
P5
tir
INT
slave address (PCF8574) data from port
12345678
P
stop
condition
tiv
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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
1
P3
R/W acknowledge
from slave
A 0
P3
A P
SDA
SCL
P3
OUTPUT
VOLTAGE
IOHt IOH
P3
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
VIVDD or VIVSS −−±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
−−1mA
Ciinput capacitance −−10 pF
Cooutput capacitance −−10 pF
Port timing; CL100 pF (see Figs 11 and 12)
tpv output data valid −−4µs
t
su input data set-up time 0 −− µs
t
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
L100 pF
tiv input data valid time −−4µs
t
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
t
SU;STA START condition set-up time 4.7 −−µs
t
HD;STA START condition hold time 4.0 −−µs
t
LOW SCL LOW time 4.7 −−µs
t
HIGH SCL HIGH time 4.0 −−µs
t
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
tf
r
t
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
MH
c
(e )
1
ME
A
L
seating plane
A1
wM
b1
b2
e
D
A2
Z
16
1
9
8
E
pin 1 index
b
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
H
L
mm
DIMENSIONS (inch dimensions are derived from the original mm dimensions)
A
min. A
max. bmax.
w
ME
e1
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)
eH
ELL
pQZ
ywv θ
REFERENCES
OUTLINE
VERSION EUROPEAN
PROJECTION ISSUE DATE
IEC JEDEC EIAJ
mm
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
o
o
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
8
16
wM
bp
D
detail X
Z
e
9
1
y
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
X
θ
A
A1
A2
HE
Lp
Q
E
c
L
vMA
(A )
3
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)
eH
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
o
o
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
wM
θ
A
A1
A2
bp
D
HE
Lp
Q
detail X
E
Z
e
c
L
vMA
X
(A )
3
A
y
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
A
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,
copyright, or mask work right to these products, and
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.