INTEGRATED CIRCUITS DATA SHEET PCF8574 Remote 8-bit I/O expander for I2C-bus Product specification Supersedes data of 2002 Jul 29 2002 Nov 22 Philips Semiconductors Product specification Remote 8-bit I/O expander for I2C-bus CONTENTS 1 FEATURES 2 GENERAL DESCRIPTION 3 ORDERING INFORMATION 4 BLOCK DIAGRAM 5 PINNING 5.1 5.2 DIP16 and SO16 packages SSOP20 package 6 CHARACTERISTICS OF THE I2C-BUS 6.1 6.2 6.3 6.4 Bit transfer Start and stop conditions System configuration Acknowledge 7 FUNCTIONAL DESCRIPTION 7.1 7.2 7.3 Addressing Interrupt output Quasi-bidirectional I/Os 8 LIMITING VALUES 9 HANDLING 10 DC CHARACTERISTICS 11 I2C-BUS TIMING CHARACTERISTICS 12 PACKAGE OUTLINES 13 SOLDERING 13.1 13.2 13.2.1 13.2.2 13.3 13.3.1 13.3.2 13.3.3 13.4 Introduction Through-hole mount packages Soldering by dipping or by solder wave Manual soldering Surface mount packages Reflow soldering Wave soldering Manual soldering 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 2 PCF8574 Philips Semiconductors Product specification Remote 8-bit I/O expander for I2C-bus 1 PCF8574 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 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 microcontroller if there is incoming data on its ports without having to communicate via the I2C-bus. This means that the PCF8574 can remain a simple slave device. • 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 The PCF8574 and PCF8574A versions differ only in their slave address as shown in Fig.10. The PCF8574 is a silicon CMOS circuit. It provides general purpose remote I/O expansion for most microcontroller families via the two-line bidirectional bus (I2C-bus). 3 ORDERING INFORMATION PACKAGE TYPE NUMBER 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 plastic shrink small outline package; 20 leads; body width 4.4 mm SOT266-1 PCF8574TS; PCF8574ATS 2002 Nov 22 SSOP20 3 Philips Semiconductors Product specification Remote 8-bit I/O expander for I2C-bus 4 PCF8574 BLOCK DIAGRAM handbook, full pagewidth INT 13 INTERRUPT LOGIC PCF8574 1 A0 A1 A2 SCL SDA LP FILTER 2 4 3 5 6 14 15 INPUT FILTER I 2 C BUS CONTROL 7 SHIFT REGISTER 8 BIT I/O PORT 9 10 11 12 WRITE pulse VDD V SS 16 8 READ pulse POWER-ON RESET MBD980 Fig.1 Block diagram (pin numbers apply to DIP16 and SO16 packages). 2002 Nov 22 4 P0 P1 P2 P3 P4 P5 P6 P7 Philips Semiconductors Product specification Remote 8-bit I/O expander for I2C-bus 5 PCF8574 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 A0 1 16 VDD A1 2 15 SDA A1 A2 3 14 SCL handbook, halfpage P0 4 16 VDD 2 15 SDA A2 3 14 SCL PCF8574P 13 INT PCF8574AP 12 P7 P1 5 P0 P2 6 11 P6 P2 6 11 P6 P3 7 10 P5 P3 7 10 P5 VSS 8 9 4 P1 5 VSS P4 PCF8574T 13 INT PCF8574AT 12 P7 8 9 P4 MCE001 MBD979 Fig.2 Pin configuration (DIP16). 2002 Nov 22 A0 1 Fig.3 Pin configuration (SO16). 5 Philips Semiconductors Product specification Remote 8-bit I/O expander for I2C-bus 5.2 PCF8574 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 1 20 P7 SCL 2 19 P6 n.c. 3 18 n.c. SDA 4 17 P5 VDD 5 16 P4 A1 7 14 P3 n.c. 8 13 n.c. PCF8574TS A0 6 PCF8574ATS 15 VSS A2 9 12 P2 P0 10 11 P1 MBD978 Fig.4 Pin configuration (SSOP20). 2002 Nov 22 6 Philips Semiconductors Product specification Remote 8-bit I/O expander for I2C-bus 6 PCF8574 6.2 CHARACTERISTICS OF THE I2C-BUS Both data and clock lines remain HIGH when the bus is not 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). The I2C-bus is for 2-way, 2-line communication between different ICs or modules. The two lines are a serial data line (SDA) and a serial clock 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. 6.3 6.1 Start and stop conditions Bit transfer 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). 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). handbook, full pagewidth SDA SCL data line stable; data valid change of data allowed MBC621 Fig.5 Bit transfer. handbook, full pagewidth SDA SDA SCL SCL S P START condition STOP condition MBC622 Fig.6 Definition of start and stop conditions. SDA SCL MASTER TRANSMITTER / RECEIVER SLAVE RECEIVER SLAVE TRANSMITTER / RECEIVER MASTER TRANSMITTER MASTER TRANSMITTER / RECEIVER MBA605 Fig.7 System configuration. 2002 Nov 22 7 Philips Semiconductors Product specification Remote 8-bit I/O expander for I2C-bus 6.4 Acknowledge PCF8574 of each byte that has been clocked out of the slave transmitter. The device that acknowledges has to pull down the 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. 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 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 the transmitter must leave the data line HIGH to enable the master to generate a stop condition. 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 handbook, full pagewidth DATA OUTPUT BY TRANSMITTER not acknowledge DATA OUTPUT BY RECEIVER acknowledge SCL FROM MASTER 1 2 8 9 S clock pulse for acknowledgement START condition MBC602 Fig.8 Acknowledgment on the I2C-bus. 2002 Nov 22 8 Philips Semiconductors Product specification Remote 8-bit I/O expander for I2C-bus 7 PCF8574 FUNCTIONAL DESCRIPTION VDD handbook, full pagewidth write pulse 100 µA data from shift register D Q FF P0 to P7 CI S power-on reset V SS D Q FF CI read pulse S to interrupt logic data to shift register MBD977 Fig.9 Simplified schematic diagram of each I/O. 7.1 Addressing For addressing see Figs 10, 11 and 12. slave address handbook, full pagewidth S 0 1 0 0 A2 slave address A1 A0 0 A S 0 1 1 1 A2 A1 A0 0 A MBD973 a. PCF8574. b. PCF8574A. Fig.10 PCF8574 and PCF8574A slave addresses. 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). 2002 Nov 22 9 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 ... 2 3 4 5 6 7 8 slave address (PCF8574) SDA S 0 1 10 start condition 0 0 A2 A1 data to port A0 0 R/W A data to port DATA 1 A acknowledge from slave DATA 2 A acknowledge from slave acknowledge from slave Philips Semiconductors 1 Remote 8-bit I/O expander for I2C-bus andbook, full pagewidth 2002 Nov 22 SCL WRITE TO PORT DATA OUT FROM PORT DATA 1 VALID t pv t pv MBD974 Product specification PCF8574 Fig.11 WRITE mode (output). DATA 2 VALID 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 ... S 0 1 start condition 0 0 A2 A1 A0 1 A R/W DATA 1 A acknowledge from slave DATA 4 acknowledge from slave 1 P stop condition READ FROM PORT 11 DATA INTO PORT DATA 2 DATA 3 t ph Philips Semiconductors SDA data from port Remote 8-bit I/O expander for I2C-bus 2002 Nov 22 data from port slave address (PCF8574) DATA 4 t ps INT t iv t ir t ir MBD975 Product specification Fig.12 READ mode (input). PCF8574 htdiwegap lluf ,koobdnah 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. Philips Semiconductors Product specification Remote 8-bit I/O expander for I2C-bus 7.2 PCF8574 • Interrupts which occur during the acknowledge clock pulse may be lost (or very short) due to the resetting of the interrupt during this pulse. 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. 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. An interrupt is generated by any rising or falling edge of the port inputs in the input mode. After time tiv the signal INT is valid. 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. Resetting and reactivating the interrupt circuit is achieved when data on the port is changed to the original setting or data is read from or written to the port which has generated the interrupt. Resetting occurs as follows: • In the READ mode at the acknowledge bit after the rising edge of the SCL signal • In the WRITE mode at the acknowledge bit after the HIGH-to-LOW transition of the SCL signal handbook, full pagewidth V DD PCF8574 (1) PCF8574 (2) PCF8574 (16) INT INT INT MICROCONTROLLER INT MBD976 Fig.13 Application of multiple PCF8574s with interrupt. slave address (PCF8574) handbook, full pagewidth SDA S 0 1 0 0 A2 A1 data from port A0 start condition SCL 1 2 1 R/W 3 4 5 6 7 A 1 acknowledge P5 from slave 1 P stop condition 8 DATA INTO P5 INT t iv t ir Fig.14 Interrupt generated by a change of input to I/O P5. 2002 Nov 22 12 MBD972 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 ... S 0 1 1 1 A2 A1 A0 start condition 1 2 R/W 3 4 5 6 7 A 1 A P3 acknowledge from slave 0 A P3 8 P P3 OUTPUT VOLTAGE P3 PULL-UP OUTPUT CURRENT I OHt I OH Product specification Fig.15 Transient pull-up current IOHt while P3 changes from LOW-to-HIGH and back to LOW. MBD971 PCF8574 handbook, full pagewidth 13 SCL 0 data to port Philips Semiconductors SDA data to port Remote 8-bit I/O expander for I2C-bus 2002 Nov 22 slave address (PCF8574A) 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). SYMBOL PARAMETER MIN. MAX. UNIT VDD supply voltage −0.5 +7.0 V VI input voltage VSS − 0.5 VDD + 0.5 V II DC input current − ±20 mA IO DC output current − ±25 mA IDD supply current − ±100 mA ISS supply current − ±100 mA Ptot total power dissipation − 400 mW PO power dissipation per output − 100 mW Tstg storage temperature −65 +150 °C Tamb ambient temperature −40 +85 °C 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 CONDITIONS MIN. TYP. MAX. UNIT Supply VDD supply voltage − 6.0 V IDD supply current operating mode; VDD = 6 V; − no load; VI = VDD or VSS; fSCL = 100 kHz 40 100 µA Istb standby current standby mode; VDD = 6 V; no load; VI = VDD or VSS − 2.5 10 µA VPOR Power-on reset voltage VDD = 6 V; no load; VI = VDD or VSS; note 1 − 1.3 2.4 V 2.5 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 IL leakage current VI = VDD or VSS −1 − +1 µA Ci input capacitance VI = VSS − − 7 pF 2002 Nov 22 14 Philips Semiconductors Product specification Remote 8-bit I/O expander for I2C-bus SYMBOL PARAMETER PCF8574 CONDITIONS MIN. TYP. MAX. UNIT 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 − − ±400 µA VI ≥ VDD or VI ≤ VSS IOL LOW level output current VOL = 1 V; VDD = 5 V 10 25 − mA IOH HIGH level output current VOH = VSS 30 − 300 µA IOHt transient pull-up current HIGH during acknowledge (see Fig.15); VOH = VSS; VDD = 2.5 V − −1 − mA Ci input capacitance − − 10 pF Co output capacitance − − 10 pF Port timing; CL ≤ 100 pF (see Figs 11 and 12) tpv output data valid − − 4 µs tsu input data set-up time 0 − − µs th input data hold time 4 − − µs Interrupt INT (see Fig.14) IOL LOW level output current VOL = 0.4 V 1.6 − − mA IL leakage current VI = VDD or VSS −1 − +1 µA TIMING; CL ≤ 100 pF tiv input data valid time − − 4 µs tir reset delay time − − 4 µs −0.5 − +0.3VDD V 0.7VDD − VDD + 0.5 V −250 − +250 nA Select inputs A0 to A2 VIL LOW level input voltage VIH HIGH level input voltage ILI input leakage current pin at VDD or VSS Note 1. The Power-on reset circuit resets the I2C-bus logic at VDD < VPOR and sets all I/Os to logic 1 (with current source to VDD). 2002 Nov 22 15 Philips Semiconductors Product specification Remote 8-bit I/O expander for I2C-bus PCF8574 11 I2C-BUS TIMING CHARACTERISTICS 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 tSU;STA START condition set-up time 4.7 − − µs tHD;STA START condition hold time 4.0 − − µs tLOW SCL LOW time 4.7 − − µs tHIGH SCL HIGH time 4.0 − − µs tr SCL and SDA rise time − − 1.0 µs tf SCL 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 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. handbook, full pagewidth t SU;STA BIT 6 (A6) BIT 7 MSB (A7) START CONDITION (S) PROTOCOL t LOW t HIGH BIT 0 LSB (R/W) ACKNOWLEDGE (A) STOP CONDITION (P) 1 / f SCL SCL t tf tr BUF SDA t HD;STA t SU;DAT t HD;DAT Fig.16 I2C-bus timing diagram. 2002 Nov 22 16 t VD;DAT MBD820 t SU;STO Philips Semiconductors Product specification Remote 8-bit I/O expander for I2C-bus PCF8574 12 PACKAGE OUTLINES DIP16: plastic dual in-line package; 16 leads (300 mil) SOT38-4 ME seating plane D A2 A A1 L c e Z w M b1 (e 1) b b2 MH 9 16 pin 1 index E 1 8 0 5 10 mm scale DIMENSIONS (inch dimensions are derived from the original mm dimensions) UNIT A max. A1 min. A2 max. b b1 b2 c D (1) E (1) e e1 L ME MH w Z (1) max. mm 4.2 0.51 3.2 1.73 1.30 0.53 0.38 1.25 0.85 0.36 0.23 19.50 18.55 6.48 6.20 2.54 7.62 3.60 3.05 8.25 7.80 10.0 8.3 0.254 0.76 inches 0.17 0.020 0.13 0.068 0.051 0.021 0.015 0.049 0.033 0.014 0.009 0.77 0.73 0.26 0.24 0.10 0.30 0.14 0.12 0.32 0.31 0.39 0.33 0.01 0.030 Note 1. Plastic or metal protrusions of 0.25 mm maximum per side are not included. OUTLINE VERSION REFERENCES IEC JEDEC EIAJ ISSUE DATE 92-11-17 95-01-14 SOT38-4 2002 Nov 22 EUROPEAN PROJECTION 17 Philips Semiconductors Product specification Remote 8-bit I/O expander for I2C-bus PCF8574 SO16: plastic small outline package; 16 leads; body width 7.5 mm SOT162-1 D E A X c HE y v M A Z 9 16 Q A2 A (A 3) A1 pin 1 index θ Lp L 1 8 e detail X w M bp 0 5 10 mm scale DIMENSIONS (inch dimensions are derived from the original mm dimensions) UNIT A max. A1 A2 A3 bp c D (1) E (1) e HE L Lp Q v w y mm 2.65 0.30 0.10 2.45 2.25 0.25 0.49 0.36 0.32 0.23 10.5 10.1 7.6 7.4 1.27 10.65 10.00 1.4 1.1 0.4 1.1 1.0 0.25 0.25 0.1 0.9 0.4 inches 0.10 0.012 0.096 0.004 0.089 0.01 0.019 0.013 0.014 0.009 0.41 0.40 0.30 0.29 0.050 0.419 0.043 0.055 0.394 0.016 0.043 0.039 0.01 0.01 0.004 0.035 0.016 Z (1) θ 8o 0o Note 1. Plastic or metal protrusions of 0.15 mm maximum per side are not included. REFERENCES OUTLINE VERSION IEC JEDEC SOT162-1 075E03 MS-013 2002 Nov 22 EIAJ EUROPEAN PROJECTION ISSUE DATE 97-05-22 99-12-27 18 Philips Semiconductors Product specification Remote 8-bit I/O expander for I2C-bus PCF8574 SSOP20: plastic shrink small outline package; 20 leads; body width 4.4 mm D SOT266-1 E A X c y HE v M A Z 11 20 Q A2 A (A 3) A1 pin 1 index θ Lp L 1 10 detail X w M bp e 0 2.5 5 mm scale DIMENSIONS (mm are the original dimensions) UNIT A max. A1 A2 A3 bp c D (1) E (1) e HE L Lp Q v w y Z (1) θ mm 1.5 0.15 0 1.4 1.2 0.25 0.32 0.20 0.20 0.13 6.6 6.4 4.5 4.3 0.65 6.6 6.2 1.0 0.75 0.45 0.65 0.45 0.2 0.13 0.1 0.48 0.18 10 0o Note 1. Plastic or metal protrusions of 0.20 mm maximum per side are not included. OUTLINE VERSION SOT266-1 2002 Nov 22 REFERENCES IEC JEDEC EIAJ EUROPEAN PROJECTION ISSUE DATE 95-02-22 99-12-27 MO-152 19 o Philips Semiconductors Product specification Remote 8-bit I/O expander for I2C-bus 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 SOLDERING 13.1 Introduction This text gives a very brief insight to a complex technology. 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). 13.3.2 There is no soldering method that is ideal for all IC packages. Wave soldering is often preferred when through-hole and surface mount components are mixed on 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 13.2.1 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: Through-hole mount packages • Use a double-wave soldering method comprising a turbulent wave with high upward pressure followed by a smooth laminar wave. SOLDERING BY DIPPING OR BY SOLDER 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; 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. – 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. • For packages with leads on four sides, the footprint must 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. 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 13.3.1 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. Surface mount packages 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. REFLOW SOLDERING Reflow soldering requires solder paste (a suspension of fine solder particles, flux and binding agent) to be applied to the printed-circuit board by screen printing, stencilling or pressure-syringe dispensing before package placement. 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. 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. 2002 Nov 22 WAVE SOLDERING Conventional single wave soldering is not recommended for surface mount devices (SMDs) or printed-circuit boards with a high component density, as solder bridging and non-wetting can present major problems. 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. 13.2.2 PCF8574 20 Philips Semiconductors Product specification Remote 8-bit I/O expander for I2C-bus 13.4 PCF8574 Suitability of IC packages for wave, reflow and dipping soldering methods MOUNTING SOLDERING METHOD PACKAGE(1) WAVE suitable(3) Through-hole mount DBS, DIP, HDIP, SDIP, SIL Surface mount REFLOW(2) DIPPING − suitable suitable − HBCC, HBGA, HLQFP, HSQFP, HSOP, HTQFP, HTSSOP, HVQFN, HVSON, SMS not suitable(4) suitable − PLCC(5), SO, SOJ suitable suitable − suitable − suitable − BGA, LBGA, LFBGA, SQFP, TFBGA, VFBGA not suitable recommended(5)(6) LQFP, QFP, TQFP not SSOP, TSSOP, VSO not recommended(7) Notes 1. For more detailed information on the BGA packages refer to the “(LF)BGA Application 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. 2002 Nov 22 21 Philips Semiconductors Product specification Remote 8-bit I/O expander for I2C-bus PCF8574 14 DATA SHEET STATUS LEVEL DATA SHEET STATUS(1) PRODUCT STATUS(2)(3) Development DEFINITION I Objective data 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 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). Production 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. 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. 15 DEFINITIONS 16 DISCLAIMERS 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. 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 Semiconductors customers using or selling these products 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. 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 at these or at any other conditions above those given in the Characteristics sections of the specification is not implied. Exposure to limiting values for extended periods may affect device reliability. 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. Application information Applications that are described herein for any of these products are for illustrative purposes only. Philips Semiconductors make no representation or warranty that such applications will be suitable for the specified use without further testing or modification. 2002 Nov 22 22 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. 2002 Nov 22 23 Philips Semiconductors – a worldwide 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: [email protected]. SCA74 © Koninklijke Philips Electronics N.V. 2002 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. Printed in The Netherlands 403512/04/pp24 Date of release: 2002 Nov 22 Document order number: 9397 750 10462