NATIONAL SEMICONDUCTOR LM48555 User's Manual
Summary
The LM48555 is a specialized audio power amplifier designed for driving ceramic speakers in various portable electronics. Optimized for applications like mobile phones, PDAs, and digital cameras, it delivers high sound quality with exceptionally low distortion (THD+N) and advanced noise rejection features. This comprehensive manual provides technical specifications, detailed operating parameters, and application circuits necessary for integrating the amplifier seamlessly into next-generation portable devices requiring reliable, crystal-clear audio performance across different power profiles.
Page 1 Text Content
ra ic r D riv
March 2007
LM48555 Ceramic Speaker Driver General Description Key Specifications The LM48555 is an audio power amplifier designed to drive
■ IDDQ (Boost Converter + Amplifier)
ceramic speakers in applications such as cell phones, smart
at VDD = 5V 7.5m A (typ)
phones, PDAs and other portable devices. The LM48555 pro-
duces 15.7VP-P with less than 1% THD+N while operating ■ Output Voltage Swing
from a 3.2V power supply. The LM48555 features a low power
VDD = 3.2V, THD ≤ 1% 15.7VP-P (typ)
shutdown mode, and differential inputs for improved noise rejection. ■ Power Supply Rejection Ratio
80d B (typ)
The LM48555 includes advanced click and pop suppression f = 217Hz
that eliminates audible turn-on and turn-off transients. Addi- tionally, the integrated boost regulator features a soft start Features function that minimizes transient current during power-up
Fully differential amplifier
Boomer audio power amplifiers were designed specifically to
Externally configurable gain
provide high quality output power with a minimal number of
external components. The LM48555 does not require boot- Soft start function
strap capacitors, or snubber circuits. Low power shutdown mode The LM48555 is unity-gain stable and uses external gain-set- Under voltage lockout ting resistors.
Applications Mobile phones PDA's Digital cameras
Typical Application
* CF+ and CF- are optional. Refer to “Selecting Input and Feedback Capacitor and Resistor for Audio Amplifier” section.
FIGURE 1. Typical Audio Amplifier Application Circuit
Boomer® is a registered trademark of National Semiconductor Corporation.
© 2007 National Semiconductor Corporation www.national.com
Page Summary Contents For NATIONAL SEMICONDUCTOR LM48555 User's Manual
Manual Details
| Brand | National |
|---|---|
| Pages | 14 |
| File Size | 332.17 KB |
| Published | June 15, 2026 |
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Frequently Asked Questions
What kind of speakers is the LM48555 designed to drive?
It is optimized to drive DDQ ceramic speakers.
Does the amplifier require external components like bootstrap capacitors or snubber circuits?
No, it does not require external bootstrap capacitors or snubber circuits.
How effective are its noise rejection features?
It shows an 80dB typ Power Supply Rejection Ratio (PSRR) and a 65dB min Common Mode Rejection Ratio (CMRR).
What advanced functions help manage power activation?
It includes advanced click and pop suppression to eliminate audible transients, plus a soft start function.