LTC3220-1_15 Datasheet, PDF (14/20 Pages) Linear Technology – 360mA Universal 18-Channel LED Driver

LTC3220/LTC3220-1
OPERATION
Bus Speed
The I²C port is designed to be operated at speeds up to
400kHz. It has built-in timing delays to ensure correct
operation when addressed from an I²C compliant master
device. It also contains input filters designed to suppress
glitches should the bus become corrupted.
Start and Stop Conditions
A bus-master signals the beginning of a communication
to a slave device by transmitting a START condition.
A START condition is generated by transitioning SDA
from high to low while SCL is high. When the master has
finished communicating with the slave, it issues a STOP
condition by transitioning SDA from low to high while
SCL is high. The bus is then free for communication with
another I²C device.
Byte Format
Each byte sent to the LTC3220/LTC3220-1 must be 8 bits
long followed by an extra clock cycle for the acknowledge
bit to be returned by the LTC3220/LTC3220-1. The data
should be sent to the LTC3220/LTC3220-1 most significant
bit (MSB) first.
Acknowledge
The acknowledge signal is used for handshaking between
the master and the slave. An acknowledge (active low)
generated by the slave (LTC3220/LTC3220-1) lets the mas-
ter know that the latest byte of information was received.
The acknowledge related clock pulse is generated by the
master. The master releases the SDA line (high) during
the acknowledge clock cycle. The slave-receiver must pull
down the SDA line during the acknowledge clock pulse
so that it remains a stable low during the high period of
this clock pulse.
Slave Address
Each version of LTC3220/LTC3220-1 responds to a unique
address which has been factory programmed (Table 1).
The eighth bit of the address byte (R/W) must be 0 for the
LTC3220/LTC3220-1 to recognize the address since it is a
write only device. This effectively forces the address to be
8 bits long where the least significant bit of the address
is 0. If the correct seven bit address is given but the R/W
bit is 1, the LTC3220/LTC3220-1 will not respond.
Table 1. LTC3220/LTC3220-1 Factory Programmed Slave
Address
PART NUMBER
SLAVE ADDRESS
LTC3220
0011100
LTC3220-1
0011101
32201fc
14