Datasheet

MAX9744
Write Byte
A write to the MAX9744 includes transmission of a
START condition, the slave address with the R/W bit set
to 0 (see Table 3), one byte of data to the command
register, and a STOP condition. Figure 6 illustrates the
proper format for one frame.
A write to the MAX9744 consists of a 6-step sequence
as seen below:
1) The master sends a START condition.
2) The master sends the 7 bits slave ID plus a write
bit (low).
3) The addressed slave asserts an ACK on the data
line.
4) The master sends 8 data bits.
5) The active slave asserts an ACK (or NACK) on the
data line.
6) The master generates a stop condition.
Speaker Volume Control
The command register is used to control the volume
level of the speaker amplifier. The two MSBs (A1 and
A0) are set to 00, while V5–V0 is the data that is written
into the addresses register to set the volume level
(Tables 5 and 6).
Filterless Modulation/PWM
The MAX9744 features two output modulation schemes:
filterless modulation or classic PWM, selectable through
the I
2
C interface. Table 6 shows the register command
to set the output scheme.
When switching between schemes, the output is not
click-and-pop protected. To have click-and-pop protec-
tion when switching between output schemes, the
device must enter shutdown mode and be configured
to the new output scheme before the 220ms startup
sequence is terminated.
20W Stereo Class D Speaker Amplifier
with Volume Control
18 ______________________________________________________________________________________
S SLAVE ADDRESS
7 BITS
WRITE BYTE FORMAT
WR ACK DATA
8 BITS
ACK P
DATA BYTE: GIVES A COMMAND.SLAVE ADDRESS:
EQUIVALENT TO CHIP-
SELECT LINE OF A
3-WIRE INTERFACE.
0
Figure 6. Write Byte Format Example
D7 (MSB) D6 D5 D4 D3 D2 D1 D0 (LSB)
A1 A0 V5 V4 V3 V2 V1 V0
Table 5. Data Byte Format
A
0
A
1
V5–V0 SETTING
00 XXXXXX Volume level (Table 7)
01 000000 Filterless modulation
01 000001 Classic PWM
A
0
A
1
V5–V0 SETTING
10 XXXXXX Reserved
11 000100 Increased volume
11 000101 Decreased volume
Table 6. Command Register Programming