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TLC59108 Datasheet, PDF (22/31 Pages) Texas Instruments – 8-BIT Fm+ I2C-BUS CONSTANT-CURRENT LED SINK DRIVER
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TLC59108
SLDS156 – MARCH 2009 .................................................................................................................................................................................................. www.ti.com
Start and Stop Conditions
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 Figure 12).
SDA
SCL
S
P
Start Condition
Stop Condition
Figure 12. Start and Stop Conditions
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 Figure 13).
SDA
SCL
Master
Transmitter/
Receiver
Slave
Receiver
Slave
Transmitter/
Receiver
Master
Transmitter
Master
Transmitter/
Receiver
I2C Bus
Multiplexer
Slave
Figure 13. System Configuration
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. 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 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 time and
hold time 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, the transmitter must leave the data line high to enable
the master to generate a Stop condition.
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