max9726aetpt Maxim Integrated Products, Inc., max9726aetpt Datasheet - Page 14

• Manufacturer Part Number: max9726aetpt
• Description: Max9726 Directdrive, Headphone Amplifier With Bassmax, I?c, Volume And Gain Control
• Manufacturer: Maxim Integrated Products, Inc.

DirectDrive, Headphone Amplifier with
BassMax, I
Figure 6. Write Data Format Example
Figure 7. Volume-Control Transfer Function
Table 2. Command Register
Table 3. Shutdown Control, SHDN = V
14
CONDITION
Disabled
Enabled
Shutdown
START
ACKNOWLEDGE FROM MAX9726
COMMAND BYTE IS STORED ON
S
______________________________________________________________________________________
B7
RECEIPT OF STOP CONDITION
SLAVE ADDRESS
100
120
MODE
20
40
60
80
0
0
BassMax
Enable
R/W
B6
16
0
CODE (DECIMAL)
A
2
B7 B6 B5 B4 B3 B2
32
C, Volume and Gain Control
COMMAND BYTE
FROM MAX9726
ACKNOWLEDGE
B5
48
B7
0
1
B1 B0
64
CONDITION
A
STOP
B4
DD
P
A write to the MAX9726 includes transmission of a
START condition, the slave address with the R/W bit set
to 0 (see Table 1), one byte of data to configure the
command register, and a STOP condition. Figure 6
illustrates the proper format for one frame.
The MAX9726 only accepts write data, but it acknowl-
edges the receipt of its address byte with the R/W bit
set to 1. The MAX9726 does not write to the SDA bus in
the event that the R/W bit is set to 1. Subsequently, the
master reads all 1’s from the MAX9726. Always set the
R/W bit to zero to avoid this situation.
The MAX9726 has one command register that is used
to enable/disable shutdown, enable/disable BassMax,
and set the volume. Table 2 describes the function of
the bits contained in the command register.
Set B7 to 0 to shutdown the MAX9726. The MAX9726
wakes up from shutdown when B7 is set to 1 provided
SHDN is high. SHDN must be high and B7 must be set
to 1 for the MAX9726 to operate normally (see Table 3).
Set B6 to 1 to enable BassMax (see Table 4). The out-
put signal’s low-frequency response is boosted accord-
ing to the external components connected between
OUT_ and BM_. See the Gain-Setting Components sec-
tion for details on choosing the external components.
Adjust the MAX9726’s volume with control bits [5:0].
The volume is adjustable to one of 64 steps ranging
from full mute to the maximum gain set by the external
components. Table 5 lists all the possible volume set-
tings for the MAX9726. Figure 7 shows the volume-con-
trol transfer function for the MAX9726.
Table 4. BassMax Control
BassMax Disabled
BassMax Enabled
Volume (See Table 5)
B3
MODE
B2
B1
Command Register
Write Data Format
B6
0
1
B0