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INTEGRATED CIRCUITS DATA SHEET PCF8591 8-bit A/D and D/A converter Product speciﬁcation Supersedes data of 2001 Dec 13 2003 Jan 27

Product speciﬁcation PCF8591 Philips Semiconductors 8-bit A/D and D/A converter CONTENTS 1 2 3 4 5 6 7 7.1 7.2 7.3 7.4 7.5 7.6 8 8.1 8.2 8.3 8.4 8.5 9 10 11 12 13 14 15 16 17 17.1 17.2 17.3 17.4 18 19 20 21 FEATURES APPLICATIONS GENERAL DESCRIPTION ORDERING INFORMATION BLOCK DIAGRAM PINNING FUNCTIONAL DESCRIPTION Addressing Control byte D/A conversion A/D conversion Reference voltage Oscillator CHARACTERISTICS OF THE I2C-BUS Bit transfer Start and stop conditions System configuration Acknowledge I2C-bus protocol LIMITING VALUES HANDLING DC CHARACTERISTICS D/A CHARACTERISTICS A/D CHARACTERISTICS AC CHARACTERISTICS APPLICATION INFORMATION PACKAGE OUTLINES SOLDERING Introduction to soldering through-hole mount packages Soldering by dipping or by solder wave Manual soldering Suitability of through-hole mount IC packages for dipping and wave soldering methods DATA SHEET STATUS DEFINITIONS DISCLAIMERS PURCHASE OF PHILIPS I2C COMPONENTS 2003 Jan 27 2

Philips Semiconductors 8-bit A/D and D/A converter FEATURES 1 • Single power supply • Operating supply voltage 2.5 V to 6 V • Low standby current • Serial input/output via I2C-bus • Address by 3 hardware address pins • Sampling rate given by I2C-bus speed • 4 analog inputs programmable as single-ended or differential inputs • Auto-incremented channel selection • Analog voltage range from VSS to VDD • On-chip track and hold circuit • 8-bit successive approximation A/D conversion • Multiplying DAC with one analog output. 2 APPLICATIONS • Closed loop control systems • Low power converter for remote data acquisition • Battery operated equipment • Acquisition of analog values in automotive, audio and TV applications. Product speciﬁcation PCF8591 3 GENERAL DESCRIPTION The PCF8591 is a single-chip, single-supply low power 8-bit CMOS data acquisition device with four analog inputs, one analog output and a serial I2C-bus interface. Three address pins A0, A1 and A2 are used for programming the hardware address, allowing the use of up to eight devices connected to the I2C-bus without additional hardware. Address, control and data to and from the device are transferred serially via the two-line bidirectional I2C-bus. The functions of the device include analog input multiplexing, on-chip track and hold function, 8-bit analog-to-digital conversion and an 8-bit digital-to-analog conversion. The maximum conversion rate is given by the maximum speed of the I2C-bus. 4 ORDERING INFORMATION TYPE NUMBER PCF8591P PCF8591T NAME DIP16 SO16 PACKAGE DESCRIPTION plastic dual in-line package; 16 leads (300 mil) plastic small outline package; 16 leads; body width 7.5 mm VERSION SOT38-4 SOT162-1 2003 Jan 27 3

Philips Semiconductors 8-bit A/D and D/A converter 5 BLOCK DIAGRAM handbook, full pagewidth Product speciﬁcation PCF8591 I2C BUS INTERFACE POWER ON RESET ANALOGUE MULTIPLEXER SCL SDA A0 A1 A2 EXT VDD VSS OSC AIN0 AIN1 AIN2 AIN3 AOUT PCF8591 STATUS REGISTER DAC DATA REGISTER ADC DATA REGISTER OSCILLATOR CONTROL LOGIC SAMPLE AND HOLD SAMPLE AND HOLD COMPARATOR SUCCESSIVE APPROXIMATION REGISTER/LOGIC DAC VREF AGND MBL821 Fig.1 Block diagram. 6 PINNING SYMBOL AINO AIN1 AIN2 AIN3 A0 A1 A2 VSS SDA SCL OSC EXT AGND VREF AOUT VDD PIN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 DESCRIPTION analog inputs (A/D converter) hardware address negative supply voltage I2C-bus data input/output I2C-bus clock input oscillator input/output external/internal switch for oscillator input analog ground voltage reference input analog output (D/A converter) positive supply voltage 2003 Jan 27 4 handbook, halfpage AIN0 AIN1 AIN2 AIN3 A0 A1 A2 VSS 1 2 3 4 5 6 7 8 16 VDD 15 AOUT 14 VREF 13 AGND 12 EXT 11 OSC 10 SCL 9 SDA PCF8591P MBL822 Fig.2 Pinning diagram (DIP16).

Philips Semiconductors 8-bit A/D and D/A converter Product speciﬁcation PCF8591 handbook, halfpage AIN0 AIN1 AIN2 AIN3 A0 A1 A2 VSS 1 2 3 4 5 6 7 8 16 VDD 15 AOUT 14 VREF 13 AGND 12 EXT 11 OSC 10 SCL 9 SDA PCF8591T MBL823 Fig.3 Pinning diagram (SO16). 7 FUNCTIONAL DESCRIPTION 7.1 Addressing Each PCF8591 device in an I2C-bus system is activated by sending a valid address to the device. The address consists of a fixed part and a programmable part. The programmable part must be set according to the address pins A0, A1 and A2. The address always has to be sent as the first byte after the start condition in the I2C-bus protocol. The last bit of the address byte is the read/write-bit which sets the direction of the following data transfer (see Figs 4, 16 and 17). handbook, halfpage msb lsb 1 0 0 1 A2 A1 A0 R/W fixed part programmable part MBL824 Fig.4 Address byte. 7.2 Control byte The second byte sent to a PCF8591 device will be stored in its control register and is required to control the device function. The upper nibble of the control register is used for enabling the analog output, and for programming the analog inputs as single-ended or differential inputs. The lower nibble selects one of the analog input channels defined by the upper nibble (see Fig.5). If the auto-increment flag is set, the channel number is incremented automatically after each A/D conversion. If the auto-increment mode is desired in applications where the internal oscillator is used, the analog output enable flag in the control byte (bit 6) should be set. This allows the internal oscillator to run continuously, thereby preventing conversion errors resulting from oscillator start-up delay. The analog output enable flag may be reset at other times to reduce quiescent power consumption. The selection of a non-existing input channel results in the highest available channel number being allocated. Therefore, if the auto-increment flag is set, the next selected channel will be always channel 0. The most significant bits of both nibbles are reserved for future functions and have to be set to logic 0. After a Power-on reset condition all bits of the control register are reset to logic 0. The D/A converter and the oscillator are disabled for power saving. The analog output is switched to a high-impedance state. 2003 Jan 27 5

Philips Semiconductors 8-bit A/D and D/A converter Product speciﬁcation PCF8591 handbook, full pagewidth msb lsb 0 X X X 0 X X X CONTROL BYTE A/D CHANNEL NUMBER: 00 01 10 11 channel 0 channel 1 channel 2 channel 3 AUTO-INCREMENT FLAG: (active if 1) ANALOGUE INPUT PROGRAMMING: 00 Four single-ended inputs AIN0 AIN1 AIN2 AIN3 channel 0 channel 1 channel 2 channel 3 channel 0 channel 1 channel 2 01 Three differential inputs AIN0 AIN1 AIN2 AIN3 10 Single-ended and differential mixed channel 0 AIN0 AIN1 channel 1 AIN2 AIN3 11 Two differential inputs AIN0 AIN1 AIN2 AIN3 channel 2 channel 0 channel 1 ANALOGUE OUTPUT ENABLE FLAG: (analogue output active if 1) MBL825 Fig.5 Control byte. 2003 Jan 27 6

Philips Semiconductors 8-bit A/D and D/A converter Product speciﬁcation PCF8591 7.3 D/A conversion The third byte sent to a PCF8591 device is stored in the DAC data register and is converted to the corresponding analog voltage using the on-chip D/A converter. This D/A converter consists of a resistor divider chain connected to the external reference voltage with 256 taps and selection switches. The tap-decoder switches one of these taps to the DAC output line (see Fig.6). The analog output voltage is buffered by an auto-zeroed unity gain amplifier. This buffer amplifier may be switched on or off by setting the analog output enable flag of the control register. In the active state the output voltage is held until a further data byte is sent. The on-chip D/A converter is also used for successive approximation A/D conversion. In order to release the DAC for an A/D conversion cycle the unity gain amplifier is equipped with a track and hold circuit. This circuit holds the output voltage while executing the A/D conversion. The output voltage supplied to the analog output AOUT is given by the formula shown in Fig.7. The waveforms of a D/A conversion sequence are shown in Fig.8. handbook, full pagewidth VREF DAC out R256 R255 R3 R2 R1 AGND FF 02 TAP DECODER 01 00 MBL826 D7 D6 D0 Fig.6 DAC resistor divider chain. 2003 Jan 27 7

Philips Semiconductors 8-bit A/D and D/A converter Product speciﬁcation PCF8591 handbook, full pagewidth msb lsb MBL827 D7 D6 D5 D4 D3 D2 D1 D0 DAC data register VAOUT VAOUT = VAGND + VREF - VAGND 7 Di · 2i 256 i = 0 VDD VREF VAGND VSS 00 01 02 03 04 HEX code FE FF Fig.7 DAC data and DC conversion characteristics. handbook, full pagewidth MBL828 PROTOCOL S ADDRESS 0 A CONTROL BYTE A DATA BYTE 1 A DATA BYTE 2 A 1 2 8 9 1 9 1 9 1 SCL SDA VAOUT high impedance state or previous value held in DAC register previous value held in DAC register value of data byte 1 Fig.8 D/A conversion sequence. time 2003 Jan 27 8

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