lm48557tlx National Semiconductor Corporation, lm48557tlx Datasheet - Page 16

• 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-ENDED INPUT CONFIGURATION
Ground-Referenced Audio Source
The LM48557 input stage is compatible with ground-refer-
enced input sources, such as CODECs with an integrated
headphone amplifier. Connect either input, IN+ or IN- to the
NON-GROUND REFERENCED AUDIO SOURCE
Stereo-to-Mono Conversion
The LM48557 can convert a single-ended stereo signal to a
mono BTL signal (Figure 10). Connect the left and right
FIGURE 9. Single-Ended Input Configuration with a Ground-Referenced Source
FIGURE 10. Single-Ended Stereo-to-Mono BTL Conversion
16
CODEC output, and connect the unused input and VCM to
the CODEC output ground (Figure 9). An input coupling ca-
pacitor in series with the source and device input is recom-
mended to block the CODEC output offset voltage, minimiz-
ing click and pop and zipper noise during volume transitions.
CODEC outputs in parallel through two equal value resistors
to either IN+ or IN-, and connect the unused input and VCM
to the CODEC ground. Select the value of the resistors based
on the desired frequency response created by the combina-
tion of the input resistor and the input coupling capacitor.
30098108
30098107