START

MSB

DEVICE ADDRESS

LSB

ACK

STOP

R/W

MSB

LSB

ACK

FIRST REGISTER BYTE

SUCCESSIVE

REGISTER BYTES

ACK

MSB

LSB

ACK

MSB

LSB

LAST REGISTER

BYTE

START

MSB

DEVICE ADDRESS

LSB

ACK

STOP

MSB

REGISTER DATA

LSB

ACK

R/W

LM48557

www.ti.com

SNAS486D – JULY 2009 – REVISED MAY 2013

A multi-byte write operation is similar to a single-byte operation, the master device issues a START condition and

device address, and the LM48557 responds with an ACK (Figure 21). The master device then transmits the first

data byte. Following the LM48557’s ACK, the master device does not issue a STOP condition, transmitting a

second data byte instead. The LM48557 responds with an ACK bit. The master device can continue to issue

data bytes, and the LM48557 will respond with an ACK, until a STOP condition is issued. Once a STOP

condition is issued, the LM48557 ignores the I2C bus until the master issues the LM48557’s device address.

Figure 20. Single-Byte Write Example

Figure 21. Multi-Byte Write Example

GENERAL AMPLIFIER FUNCTION

The LM48557 is a fully differential ceramic speaker driver that utilizes Ti’s inverting charge pump technology to

deliver over 5.8VRMS to a 1µF ceramic speaker while operating from a single 4.2V supply. The low noise,

inverting charge pump generates a negative supply voltage (CPVSS) from the positive supply voltage (PVDD). The

LM48557 takes advantage of the increased head room created by the charge pump and the bridge-tied load

(BTL) architecture, delivering significantly more voltage than a single-ended, single-supply amplifier to the

speaker.

Table 6. Volume Control Table

VOLUME

VOL5

VOL4

VOL3

VOL2

VOL1

VOL0

GAIN (dB)

STEP

1 (MUTE)

0

0

0

0

0

0

-90

2

0

0

0

0

0

1

-25

3

0

0

0

0

1

0

-22

4

0

0

0

0

1

1

-19

5

0

0

0

1

0

0

-16

6

0

0

0

1

0

1

-13

7

0

0

0

1

1

0

-10

8

0

0

0

1

1

1

-8

9

0

0

1

0

0

0

-6

10

0

0

1

0

0

1

-4

11

0

0

1

0

1

0

-2

12

0

0

1

0

1

1

0

13

0

0

1

1

0

0

2

14

0

0

1

1

0

1

4

15

0

0

1

1

1

0

6

16

0

0

1

1

1

1

8

17

0

1

0

0

0

0

10

18

0

1

0

0

0

1

12

19

0

1

0

0

1

0

14

20

0

1

0

0

1

1

16

21

0

1

0

1

0

0

18

22

0

1

0

1

0

1

20

23

0

1

0

1

1

0

22

24

0

1

0

1

1

1

24

Copyright © 2009–2013, Texas Instruments Incorporated

Submit Documentation Feedback

11

Product Folder Links: LM48557