MAX8709B Datasheet, PDF (16/24 Pages) Maxim Integrated Products – High-Efficiency CCFL Backlight Controller with SMBus Interface

High-Efficiency CCFL Backlight
Controller with SMBus Interface
Write-Byte Format
S
ADDRESS
7 BITS
SLAVE ADDRESS
WR ACK
1B
1B
COMMAND
8 BITS
ACK
1B
DATA
8 BITS
ACK
P
1B
COMMAND BYTE: SELECTS
WHICH REGISTER YOU ARE
WRITING TO
DATA BYTE: DATA GOES INTO THE
REGISTER SET BY THE COMMAND BYTE
Read-Byte Format
S ADDRESS WR ACK COMMAND ACK S ADDRESS RD ACK
7 BITS
1B 1B
8 BITS
1B
7 BITS
1B 1B
DATA
8 BITS
/// P
1B
SLAVE ADDRESS
COMMAND BYTE: SELECTS
WHICH REGISTER YOU ARE
READING FROM
SLAVE ADDRESS: REPEATED DATA BYTE: READS FROM
DUE TO CHANGE IN DATA- THE REGISTER SET BY THE
FLOW DIRECTION
COMMAND BYTE
Send-Byte Format
Receive-Byte Format
S ADDRESS WR ACK COMMAND ACK P
S ADDRESS RD
7 BITS 1B 1B
8 BITS
1B
7 BITS
1B
COMMAND BYTE: SENDS COMMAND
WITH NO DATA; USUALLY USED FOR
ONE-SHOT COMMAND
SLAVE ADDRESS
S = START CONDITION
P = STOP CONDITION
SHADED = SLAVE TRANSMISSION
ACK= ACKNOWLEDGED = 0
/// = NOT ACKNOWLEDGED = 1
WR = WRITE = 0
RD = READ =1
ACK
DATA
/// P
1B
8 BITS
1B
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
Figure 6. SMBus Protocols
SMBus Interface (SDA, SCL)
The MAX8709B supports an Intel SMBus-compatible 2-
wire digital interface. SDA is the bidirectional data line
and SCL is the clock line of the 2-wire interface corre-
sponding respectively to SMBDATA and SMBCLK lines of
the SMBus. SDA and SCL are Schmidt-triggered inputs
that can accommodate slow edges; however, the rising
and falling edges should still be faster than 1µs and
300ns, respectively. The MAX8709B use the write-byte,
read-byte, and receive-byte protocols (Figure 6). The
SMBus protocols are documented in System Manage-
ment Bus Specification V1.1 and are available at
http://www.SMBus.org/.
The MAX8709B is a slave-only device and responds to
the 7-bit address 0b01011000 (i.e., with the R/W bit clear
indicating a write, this corresponds to 0x58). The
MAX8709B has three functional registers: a 5-bit bright-
ness register (BRIGHT4–BRIGHT0), a 3-bit shutdown-
mode register (SHMD2–SHMDE0), and a 2-bit status
register (STATUS1–STATUS0). In addition, the device has
three identification (ID) registers: an 8-bit chip ID register,
an 8-bit chip revision register, and an 8-bit manufacturer
ID register.
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