DS3508E+T&R/C Maxim Integrated, DS3508E+T&R/C Datasheet - Page 12

• Manufacturer Part Number: DS3508E+T&R/C
• Description: LCD Gamma Buffers I2C 8Ch Gamma Buffer w/EEPROM
• Manufacturer: Maxim Integrated

Specifications of DS3508E+T&R/C

• Rohs: yes
• Factory Pack Quantity: 2500
• Part # Aliases: 90-3508F+C00

I
Byte read: A byte read is an 8-bit information transfer
from the slave to the master plus a 1-bit ACK or NACK
from the master to the slave. The 8 bits of information
that are transferred (most significant bit first) from the
slave to the master are read by the master using the bit
read definition, and the master transmits an ACK using
the bit write definition to receive additional data bytes.
The master must NACK the last byte read to terminate
communication so the slave returns control of SDA to
the master.
Slave address byte: Each slave on the I
responds to a slave address byte sent immediately fol-
lowing a START condition. The slave address byte con-
tains the slave address in the most significant 7 bits
and the R/W bit in the least significant bit.
The DS3508’s slave address is determined by the state
of the A0 address pin as shown in Figure 3. An address
pin connected to GND results in a 0 in the correspond-
ing bit position in the slave address. Conversely, an
address pin connected to V
responding bit positions.
When the R/W bit is 0 (such as in E8h), the master is
indicating that it will write data to the slave. If R/W = 1
(E9h in this case), the master is indicating that it wants
to read from the slave.
If an incorrect slave address is written, the DS3508
assumes the master is communicating with another I
device and ignores the communication until the next
START condition is sent.
Memory address: During an I
master must transmit a memory address to identify the
memory location where the slave is to store the data.
The memory address is always the second byte trans-
mitted during a write operation following the slave
address byte.
See Figure 5 for I
Writing a single byte to a slave: The master must gen-
erate a START condition, write the slave address byte
(R/W = 0), write the memory address, write the byte of
data, and generate a STOP condition. Remember the
master must read the slave’s acknowledgment during
all byte write operations.
When writing to the DS3508, the DAC adjusts to the new
setting following a STOP. The EEPROM (used to make
the setting NV) is written following the STOP condition at
the end of the write command if the MODE bit is set to 0.
12
2
C, 8-Channel Gamma Buffer with EEPROM
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2
C communication examples.
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I
2
results in a 1 in the cor-
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C Communication
C write operation, the
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Writing multiple bytes to a slave: To write multiple
bytes to a slave in one transaction, the master gener-
ates a START condition, writes the slave address byte
(R/W = 0), writes the starting memory address, writes
up to 4 data bytes, and generates a STOP condition.
The DS3508 can write 1 to 4 bytes (1 page or row) in a
single write transaction. This is internally controlled by
an address counter that allows data to be written to
consecutive addresses without transmitting a memory
address before each data byte is sent. The address
counter limits the write to one 4-byte page. The first
page begins at address 00h and the second page
begins at 04h. Attempts to write to additional pages of
memory without sending a STOP condition between
pages results in the address counter wrapping around
to the beginning of the present row. To prevent address
wrapping from occurring, the master must send a
STOP condition at the end of the page, then wait for the
bus-free or EEPROM-write time to elapse. Then the
master can generate a new START condition, and write
the slave address byte (R/W = 0) and the first memory
address of the next memory row before continuing to
write data.
Acknowledge polling: Any time a EEPROM byte is
written, the DS3508 requires the EEPROM write time
(t
the byte to EEPROM. During the EEPROM write time,
the device does not acknowledge its slave address
because it is busy. It is possible to take advantage of
this phenomenon by repeatedly addressing the
DS3508, which allows communication to continue as
soon as the DS3508 is ready. The alternative to
acknowledge polling is to wait for a maximum period of
t
Reading a single byte from a slave: Unlike the write
operation that uses the specified memory address byte
to define where the data is to be written, the read opera-
tion occurs at the present value of the memory address
counter. To read a single byte from the slave, the master
generates a START condition, writes the slave address
byte with R/W = 1, reads the data byte with a NACK to
indicate the end of the transfer, and generates a STOP
condition. However, since requiring the master to keep
track of the memory address counter is impractical, the
following method should be used to perform reads from
a specified memory location.
Reading multiple bytes from a slave: The read opera-
tion can be used to read multiple bytes with a single
transfer. When reading bytes from the slave, the master
simply ACKs the data byte if it desires to read another
W
W
to elapse before attempting to access the device.
) after the STOP condition to write the contents of