Datasheet

Reference

2-11

Operation

Data must be written to and read from these registers sequentially, in the order

shown in the above table. This allows for a much shorter data stream, since

the address for each register does not have to be sent/received and

acknowledged before data can be written to or read from each register. For

example, a typical write operation could be as follows:

1) 11011000 — Address of TPA0172 with write bit set

2) Acknowledge sent back by the TPA0172

3) 00000011 — Right gain register 1 set to 16.25 dB

4) Acknowledge sent back by the TPA0172

5) 00000011 — Left gain register 1 set to 16.25 dB

6) Acknowledge sent back by the TPA0172

7) 00000011 — Right gain register 2 set to 16.25 dB

8) Acknowledge sent back by the TPA0172

9) 00000011 — Left gain register 2 set to 16.25 dB

10) Acknowledge sent back by the TPA0172

11) 00000000 — Mask register — enable internal SHUTDOWN (bit 2),

SE/BTL

(bit 1), and PCB ENABLE (bit 0)

12) Acknowledge sent back by the TPA0172

13) 00001000 — Control register — disable PCBEEP input (bit 7), gain

(bit 3), reserved (bit 2), LINE inputs selected (bit 1), SHUTDOWN low for

normal operation (bit 0)

14) Acknowledge sent back by the TPA0172

Each time the TPA0172 receives a write instruction from the I2C bus, all six

registers must be sent an 8-bit number. Conversely, each time the TPA0172

receives a read instruction, the device sends the values stored in all six

registers, in sequential order, to the I

C bus starting with the gain right register

1 and ending with the control register.

2.5.3.1 ADDRESS1 and ADDRESS0 Operation

The ADDRESS1 and ADDRESS0 pins allow the specific I

C address of the

TPA0172 to be set, allowing up to four amplifiers to be controlled through the

same I

C bus. The 8-bit I

C address of the TPA0172 is 11011a1a0(r/w), with

bit 2 (a1) set by ADDRESS1, bit 1 (a0) set by ADDRESS0, and bit 0 (r/w) as

the read/write bit. For example, pulling ADDRESS1 high and ADDRESS0 low

would give an address of 1101110(r/w). Note that the high and low values are

relative to V

, not I

. As a result, the trip point is approximately V

/2.