ST AN2474 APPLICATION NOTE
AN2474
Application note
TS4995 1.2W fully differential audio power amplifier with selectable
standby and 6db fixed gain - Evaluation board user guidelines
Introduction
This application note describes the DEMO TS4995, an evaluation board specifically
designed for the TS4995 differential audio amplifier. In this document, you will find:
● a brief description of the TS4995 differential audio amplifier ,
● a description of the evaluation board,
● a detailed list of evaluation board components,
● the layout of the evaluation board.
About the TS4995
The TS4995 is fully differential structure po wer audio amplifier which is capab le of deliv ering
1.2W of continuous RMS output power into an 8Ω load at 5V. Due to its differential inputs, it
exhibits outstanding noise immunity.
An external standby mode control reduces the supply curre nt to less than 10nA. A STBY
MODE pin allows the standby to be acti ve High or Low. An internal thermal shutdown
protection is also provided, making the device capable of su staining short-circuits.
The TS4995 features an internal fixed gain at 6dB which reduces the number of external
components on the application board, and the flip-chip package with 9 bumps allows
maximum space saving.
Its key features are:
● Differential inputs
● 90dB PSRR @ 217Hz with grounded inputs
● Operating range from V
● 1.2W rail to rail output power @ V
● 6dB integrated fixed gain
● Ultra-low consumption in standby mode (10nA)
● Selectable standby mode (active low or active high)
● Ultra-fast startup time: 10ms typ. at V
● Available in 9-bump flip-chip (300mm bump diameter)
● Ultra-low pop & click
Figure 1 on page 2 shows a typical application for the TS4995 amplifier.
For more detailed information about the TS4995, refer to the datasheet.
= 2.5V to 5.5V
CC
CC
=5V, THD+N=1%, F=1kHz, with 8Ω load
=3.3V
CC
January 2007 Rev 1 1/7
www.st.com
Typical application AN2474
1 Typical application
Figure 1. Typical application for the TS4995 audio amplifier
VCC
Cs1
1uF
VinP1
P2
Vin+
Optional
Cin1
330nF
Cin2
330nF
Cbypass1
1uF
3
1
8
VCC
TS4995
Vin-
Vin+
BYPASS
STDBY
2
3
2
Vcc
TS4995 FlipChip
+
Vo-
Vo+
7
5
8 Ohms
BIAS
STBY
STDBY MO DE
4
9
2
1
STD BY / Ope ration
1
3
GND
6
STDBY MODE
2/7
AN2474 Description of the evaluation board
2 Description of the evaluation board
The DEMO TS4995 is an evaluation board designed to help you evaluate the TS4995 low
power differential audio amplifier.
This section explains how to evaluate the amplifier in a ty pical application configuration.
Using the board, you can:
● set the amplifier in standby/operat ion mode,
● select standby mode (active low or active high),
● modify the input configuration from capacitor coupled to common mode feedback.
The Cn4 connector is used to select between standby or operation mode; and the Cn5
connector is used for standby to select between active low or active high. For example, in
Figure 2, the jumper that connects pin 2 and pin 3 of the Cn4 connector puts the device in
standby mode, while the jumper t hat connects pin1 and pin 2 of the Cn5 connector
determines that the standby is active high.
When the amplifier is used in common mode feedback input configuration, the input
capacitors are shorted by placing jumpers on connectors Cn2 and Cn3.
Figure 2. Evaluation board schematic diagram
JP1
VCC
Cn1
12
Cs
1uF
STBY MODE
8
Cn5
1
2
3
4
Vcc
Vo-
13
Vo+
+
GND
11
9
JP2
1
2
Cn2
Cin1
4
3
2
1
1 2
330nF
Cin2
1 2
330nF
Cn3
U1
TS4995
5
Vin-
3
Vin+
2
BYPASS
12
Cb
1uF
Cn4
1
2
3
BIAS
STBY
STBY
6
VCC VCC
3/7
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