lm48557tlx National Semiconductor Corporation, lm48557tlx Datasheet - Page 12

• Manufacturer Part Number: lm48557tlx
• Description: Mono, Bridge-tied Load, Ceramic Speaker Driver With I2c Volume Control And Reset
• Manufacturer: National Semiconductor Corporation

www.national.com
SINGLE AND MULTI-BYTE WRITE OPERATION
The LM48557 supports both single-byte and multi-byte write
operations. A single-byte write operation begins with the mas-
ter device transmitting a START condition followed by the
device address (Figure 7). After receiving the correct device
address, the LM48557 generates an ACK bit. The master de-
vice transmits the register data byte, after which the LM48557
generates and ACK bit. Following the ACK, the master issues
a STOP condition, completing the singly-byte data transfer.
A multi-byte write operation is similar to a single-byte opera-
tion, the master device issues a START condition and device
GENERAL AMPLIFIER FUNCTION
The LM48557 is a fully differential ceramic speaker driver that
utilizes National’s inverting charge pump technology to deliv-
er over 5.8V
from a single 4.2V supply. The low noise, inverting charge
pump generates a negative supply voltage (CPV
RMS
to a 1µF ceramic speaker while operating
FIGURE 7. Single-Byte Write Example
FIGURE 8. Multi-Byte Write Example
SS
) from the
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address, and the LM48557 responds with an ACK (Figure 8).
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 I
master issues the LM48557’s device address.
positive supply voltage (PV
tage of the increased head room created by the charge pump
and the bridge-tied load (BTL) architecture, delivering signif-
icantly more voltage than a single-ended, single-supply am-
plifier to the speaker.
DD
). The LM48557 takes advan-
2
C bus until the
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