MAX6948B MAXIM [Maxim Integrated Products], MAX6948B Datasheet - Page 24

• Manufacturer Part Number: MAX6948B
• Description: High-Efficiency PWM LED Driver with Boost Converter and Five Constant-Current GPIO Ports
• Manufacturer: MAXIM [Maxim Integrated Products]

High-Efficiency PWM LED Driver with Boost
Converter and Five Constant-Current GPIO Ports
A write to the MAX6948B comprises the transmission of
the slave address with the R/W bit set to zero, followed
by at least 1 byte of information. The first byte of infor-
mation is the command byte. The command byte deter-
mines which register of the MAX6948B is to be written by
the next byte, if received. If a STOP condition is detected
after the command byte is received, the MAX6948B
takes no further action (Figure 13) beyond storing the
command byte.
Any bytes received after the command byte are data
bytes. The first data byte goes into the internal regis-
ter of the MAX6948B selected by the command byte
(Figure 14).
If multiple data bytes are transmitted before a STOP
condition is detected, these bytes are generally stored
in subsequent MAX6948B internal registers because
24
Figure 13. Command Byte Received
Figure 14. Command and Single Data Byte Received
Figure 15. N Data Bytes Received
Message Format for Writing the LED Driver
S
S
HOW COMMAND BYTE AND DATA BYTE MAP INTO
HOW COMMAND BYTE AND DATA BYTE MAP INTO
S
ACKNOWLEDGE FROM MAX6948B
ACKNOWLEDGE FROM MAX6948B
SLAVE ADDRESS
SLAVE ADDRESS
MAX6948B REGISTERS
MAX6948B REGISTERS
COMMAND BYTE IS STORED ON RECEIPT OF
SLAVE ADDRESS
R/W
R/W
ACKNOWLEDGE FROM MAX6948B
0
0
A
A
D15 D14 D13 D12 D11 D10
D15 D14 D13 D12 D11 D10
STOP CONDITION
R/W
ACKNOWLEDGE FROM MAX6948B
ACKNOWLEDGE FROM MAX6948B
0
COMMAND BYTE
COMMAND BYTE
A
D15
the command-byte address generally autoincrements
(Table 1).
The MAX6948B is read using the MAX6948B’s internally
stored command byte as an address pointer, the same
way the stored command byte is used as an address
pointer for a write. The pointer generally autoincrements
after each data byte is read using the same rules as for
a write (Table 1). Thus, a read is initiated by first config-
uring the MAX6948B’s command byte by performing a
write (Figure 13). The master can now read n consecu-
tive bytes from the MAX6948B, with the first data byte
being read from the register addressed by the initialized
command byte. When performing read-after-write verifi-
cation, remember to reset the command byte’s address
because the stored command-byte address is generally
autoincremented after the write (Figure 15, Table 1).
D14
D9
D9
D8
D8
D13
A
A
D12
COMMAND BYTE
ACKNOWLEDGE FROM MAX6948B
D7
D7
D11
AUTOINCREMENT MEMORY ADDRESS
AUTOINCREMENT MEMORY ADDRESS
D6
D6
Message Format for Reading
D10
D5
D5
ACKNOWLEDGE FROM MAX6948B
ACKNOWLEDGE FROM MAX6948B
DATA BYTE
DATA BYTE
D4
D4
D9
BYTES
BYTE
N
1
D3
D3
D8
D2
D2
A
D1
D1
P
D0
D0
A
A
P
P