Novel audio amp design cuts out bypass capacitor

Edited by the Electronicstalk editorial team Aug 21, 2003

The latest Boomer audio amplifier from National Semiconductor eliminates the bypass capacitor typically connected to the reference voltage pin.

The latest Boomer audio amplifier from National Semiconductor eliminates the bypass capacitor typically connected to the reference voltage pin.

National's new architecture improves power supply rejection ratio and provides very fast turn-on times.

These features are ideal for applications in small, portable devices such as mobile phones and notebook computers.

"National Semiconductor is continuing to expand its Boomer amplifier portfolio with a product that sets the pace for the audio amplifier market", said Ken Boyce, Marketing Director for National Semiconductor's Audio Products Group.

"National's LM4906 features patent-pending architecture that eliminates the need for the reference voltage bypass capacitor, thereby reducing system cost, saving board space and manufacturing time for customers.

The product's fast turn-on and turn-off times are also very important for power consumption, enabling aggressive power management and longer talk time in cellular applications".

Designed to improve overall system performance, the LM4906 was created for demanding applications in mobile phones and other portable communication devices.

It is capable of delivering 1W of continuous average power to an 8ohm bridge-tied load with less than 1% total harmonic distortion plus noise from a 5V DC power supply.

The LM4906 has an internal selectable gain of either 6 or 12dB.

It does not require output coupling capacitors or bootstrap capacitors.

The LM4906 contains advanced pop and click circuitry that eliminates noise which would otherwise occur during turn-on and turn-off transitions.

Additionally, the LM4906 features a low power consumption shutdown mode (the part is enabled by pulling the shutdown pin high) and an internal thermal shutdown protection mechanism.

The LM4906 is available now in LLP chip-scale packaging and mini SOIC packaging and is priced at $0.60 in 1000-unit quantities.