Datasheet

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SLOS327C − AUGUST 2000 − REVISED MAY 2001
28
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
slave address
The slave address for the TPA0172 consists of 7 bits of address information along with 1 bit, the LSB, reserved
for read/write information. There are eight possible addresses (including the read/write bit) for this device that
can be selected with the external A1 and A0 address pins. The most significant 5 bits of the address are fixed.
Table 7 lists the possible addresses for the TPA0172.
Table 7. Valid Slave Addresses
FIXED ADDRESS
SELECTABLE WITH
ADDRESS PINS
READ/WRITE
BIT
BIT 7 (MSB) BIT 6 BIT 5 BIT 4 BIT 3
BIT 2
(A1)
BIT 1
(A0)
BIT 0
(R/W
)
1 1 0 1 1 0 0 0
1 1 0 1 1 0 0 1
1 1 0 1 1 0 1 0
1 1 0 1 1 0 1 1
1 1 0 1 1 1 0 0
1 1 0 1 1 1 0 1
1 1 0 1 1 1 1 0
1 1 0 1 1 1 1 1
gain register operation
The gain of the TPA0172 ranges from 20 dB to −60 dB in 64 1.25-dB steps. At power-up, both the right and left
channels are set at −60 dB. The truth table shown in Table 8 gives examples of valid values that may be read
from or written to the four gain setting registers. Note that the amplifier is muted if either bit 7 or bit 6 is set.
Furthermore, to avoid any unwanted clicks or pops, the gain settings should not be changed until the amplifier
has completed the power-up sequence, which can be determined by monitoring bit 7 of the mask register. When
the bit goes to 0, the power-up sequence is complete.
Table 8. Gain Settings Truth Table
GAIN (dB)
BIT 7
(MSB)
BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1
BIT 0
(LSB)
20 0 0 0 0 0 0 0 0
18.75 0 0 0 0 0 0 0 1
17.5 0 0 0 0 0 0 1 0
16.25 0 0 0 0 0 0 1 1
… … … … … … … … …
−57.5 0 0 1 1 1 1 0 1
−58.75 0 0 1 1 1 1 1 0
−60 0 0 1 1 1 1 1 1
−85 (mute) 1 1 X X X X X X