MAX1739EEP+ Maxim Integrated Products, MAX1739EEP+ Datasheet - Page 21

• Manufacturer Part Number: MAX1739EEP+
• Description: Display Drivers Wide Brightness Rang e CCFL Backlight Con
• Manufacturer: Maxim Integrated Products

Specifications of MAX1739EEP+

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 11. SMBus Protocols
Send-Byte Format
has three identification (ID) registers: an 8-bit chip ID
register, an 8-bit chip revision register, and an 8-bit
manufacturer ID register.
The CRF/SDA and CTL/SCL pins have Schmidt-trig-
gered inputs that can accommodate slow edges; how-
ever, the rising and falling edges should still be faster
than 1µs and 300ns, respectively.
Communication starts with the master signaling the
beginning of a transmission with a START condition,
which is a high-to-low transition on CRF/SDA while
CTL/SCL is high. When the master has finished com-
municating with the slave, the master issues a STOP
condition (P), which is a low-to-high transition on
CRF/SDA while CTL/SCL is high (Figures 10, 11). The
bus is then free for another transmission. Figures 12
and 13 show the timing diagram for signals on the
2-wire interface. The address byte, command byte, and
data byte are transmitted between the START and
STOP conditions. The CRF/SDA state is allowed to
change only while CTL/SCL is low, except for the
Write-Byte Format
Read-Byte Format
S = Start condition
P = Stop condition
S
S
S
ADDRESS
Slave Address
7 bits
ADDRESS
7 bits
Slave Address
ADDRESS
7 bits
WR
1b
______________________________________________________________________________________
Shaded = Slave transmission
Ack= Acknowledged = 0
/// = Not acknowledged = 1
WR
1b
ACK
1b
ACK
1b
COMMAND
WR
1b
8 bits
COMMAND
Command Byte: sends command
with no data; usually used for one-
shot command
Command Byte: selects
which register you are
reading from
8 bits
ACK
1b
ACK
1b
Command Byte: selects
which register you are
writing to
ACK
CCFL Backlight Controllers
WR = Write = 0
RD = Read =1
1b
P
COMMAND
Receive-Byte Format
8 bits
S
S
Wide Brightness Range
START and STOP conditions. Data is transmitted in 8-
bit words and is sampled on the rising edge of
CTL/SCL. Nine clock cycles are required to transfer each
byte in or out of the MAX1739 since either the master or
the slave acknowledges the receipt of the correct byte
during the ninth clock. If the MAX1739 receives its correct
slave address followed by RW = 0, it expects to receive 1
or 2 bytes of information (depending on the protocol). If
the device detects a start or stop condition prior to clock-
ing in the bytes of data, it considers this an error condition
and disregards all of the data. If the transmission is com-
pleted correctly, the registers are updated immediately
after a STOP (or RESTART) condition. If the MAX1739
receives its correct slave address followed by RW = 1, it
expects to clock out the register data selected by the pre-
vious command byte.
The MAX1739 registers are accessible through several
different redundant commands (i.e., the command byte
in the read-byte and write-byte protocols), which can
ADDRESS
ADDRESS
Slave Address: repeated
due to change in data-
flow direction
7 bits
7 bits
Slave Address
ACK
1b
RD
RD
1b
1b
Data Byte: data goes into the register
set by the command byte
ACK
ACK
1b
1b
DATA
8 bits
DATA
DATA
SMBus Commands
8 bits
Data Byte: reads from
the register set by the
command byte
8 bits
Data Byte: reads data from
the register commanded
by the last read-byte or
write-byte transmission;
also used for SMBus Alert
Response return address
ACK
1b
1b
1b
///
///
P
P
P
21