PCF8591
NXP Semiconductors
8-bit A/D and D/A converter
MASTER
TRANSMITTER/
RECEIVER
MASTER
TRANSMITTER/
RECEIVER
SLAVE
TRANSMITTER/
RECEIVER
SLAVE
RECEIVER
MASTER
TRANSMITTER
SDA
SCL
mga807
Fig 13. System configuration
9.4 Acknowledge
The number of data bytes transferred between the START and STOP conditions from
transmitter to receiver is unlimited. Each byte of 8 bits is followed by an acknowledge
cycle.
• A slave receiver, which is addressed, must generate an acknowledge after the
reception of each byte
• Also a master receiver must generate an acknowledge after the reception of each
byte that has been clocked out of the slave transmitter
• The device that acknowledges must 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 considered)
• 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
Acknowledgement on the I2C-bus is shown in Figure 14.
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 14. Acknowledgement on the I2C-bus
9.5 I2C bus protocol
After a START condition, the I2C slave address has to be sent to the PCF8591 device.
PCF8591
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© NXP B.V. 2013. All rights reserved.
Product data sheet
Rev. 7 — 27 June 2013
12 of 31
NXP [ NXP ]
