AN2622 Datasheet, PDF (1/5 Pages) STMicroelectronics – TS4909 low power stereo headphone amplifier

AN2622
Application note
TS4909 low power stereo headphone amplifier
evaluation board user guidelines
Introduction
This application note concerns the DEMOTS4909 evaluation board, designed to evaluate
the TS4909 low power stereo headphone amplifier with capacitor-less output.
In this document, you will find:
■ a brief description of the TS4909 audio amplifier
■ a description of the evaluation board and all of its components
■ the layout of the evaluation board
About the TS4909
The TS4909 is a stereo audio amplifier designed to drive headphones in portable
applications.
The integrated phantom ground is a circuit topology that eliminates the heavy output
coupling capacitors. This is of primary importance in portable applications where space
constraints are very high. A single-ended configuration is also available, offering even lower
power consumption because the phantom ground can be switched off.
Specially designed for applications requiring low power supplies, the TS4909 is capable of
delivering 52mW of continuous average power into a 32Ω load with less than 1% THD+N
from a 3V power supply. Pop & click noise during switch-on and switch-off phases is
eliminated thanks to integrated circuitry.
Key features of the TS4909 include:
■ No output coupling capacitors necessary
■ Pop & click noise reduction circuitry
■ Operating from V_CC = 2.2V to 5.5V
■ Standby mode active low
■ Output power:
– 158mW @5V, into 16Ω with 1% THD+N max (1kHz)
– 52mW @3.0V into 32Ω with 1% THD+N max (1kHz)
■ Ultra low current consumption: 2.0mA typ.@3V
■ Ultra low standby consumption: 10nA typ.
■ High signal-to-noise ratio 105dB typ. @5V
■ High crosstalk immunity: 110dB (F=1kHz)
■ PSRR: 72dB (F=1kHz), inputs grounded
■ Low t_WU: 50ms in PHG mode, 100ms in SE mode
■ Available in lead-free DFN10 3x3mm
For complete information about the TS4909, refer to the datasheet.
September 2007
Rev 1
1/5
www.st.com