Date: 27/02/2011

National Semiconductor packs class D, class G amplifier and ALC in a small size chip

National Semiconductor has integrated 1.4W Class D speaker amplifier, 20 mW Class G headphone amplifier and ALC in a small 2.55 mm by 3.02 mm package. This chip is designed for use as audio amplifier in smartphones and feature phones.

The key features of LM49251 include:
1. Its Class G headphone amp dynamically reduces the supply voltage to lower power consumption.
2. The loudspeaker's ALC provides designers with a programmable output power limiter for speaker protection and clip level to reduce audio distortion. ALC boosts small signals without clipping high level signals.
3. The LM49251 consumes less than 7 mA of quiescent current at 3.3V for the loudspeaker and headphone. The LM49251's ALC feature provides designers.
4. LM49251 provides enhanced Emission Suppression (E2S) and a Class D amplifier featuring a patented, ultra-low EMI pulse-width modulation (PWM) architecture to reduce RF emissions.
5. Its multiple inputs provide configurability for addressing different system requirements.
6. LM49251's mode selection, shutdown and volume are controlled through an I2C compatible interface.
7. The IC's click-and-pop suppression eliminates audible transients on power up and during shutdown.

National also introduced the LM49153 mono audio subsystem, which includes the same features as the LM49251, while integrating noise gate functionality onto the Class D amplifier. The noise gate feature prevents noise from being amplified when the volume is turned up. The LM49153 is offered in a 25-bump, 2.30 mm by 2.42 mm, micro SMD package.

Package:
LM49251: 30-bump 2.55 mm by 3.02 mm micro SMD package
LM49153: 25-bump 2.30 mm by 2.42 mm, micro SMD package.

Availability: Now
Price:
LM49251: Each $1.60 for 1K pieces
LM49153: Each $1.50 for 1K pieces

Editorial Product Rating: ** (Average Plus)

For more details visit: www.national.com