ST AN2862 APPLICATION NOTE

AN2862

Application note

Demonstration board user guidelines for the TS2007FC

3 W filter-free class D audio amplifier with 6-12 dB fixed gain select

Introduction

This application note concerns the TS2007FC demonstration board, designed to evaluate the class D audio differential amplifier TS2007FC.

This document provides:

■ a brief description of the TS2007FC device.

■ a description of the demonstration board and all of its components.

■ the layout of the demonstration board.

About the TS2007FC

The TS2007FC is an audio power class D amplifier that can drive up to 1.4 W into an 8 Ω load at 5 V. It achieves better efficiency compared to a typical class AB audio power amplifier.

This device allows switching between two different gains: 6 or 12 dB via a logic signal on the GS pin. Pop and click reduction circuitry provides low on/off switch noise while allowing the device to start within 1 ms. A standby function (active low) reduces the current consumption to 1 μA typical. The TS2007FC also integrates an output short-circuit protection mechanism and thermal shutdown protection to avoid damage to the amplifier.

Key features of the TS2007FC

■ Operating range from V

■ Standby mode active low.

■ Output power: 1.4 W at 5 V or 0.5 W at 3.0 V into 8 Ω with 1% THD+N maximum.

■ Output power: 2.3 W at 5 V or 0.75 W at 3.0 V into 4 Ω with 1% THD+N maximum.

■ Two fixed gain selects: 6 or 12 dB.

■ Low current consumption.

■ Efficiency: 88% typical.

■ Signal-to-noise ratio: 90 dB typical.

■ PSRR: 68 dB typical at 217 Hz with 6 dB gain.

■ PWM base frequency: 280 kHz

■ Low pop and click noise.

■ Thermal shutdown protection.

■ Output short-circuit protection.

■ Flip-chip lead-free 9-bump package.

Refer to the datasheet for complete information on the TS2007FC.

= 2.4 to 5.5 V.

February 2009 Rev 1 1/7

www.st.com

Description of the evaluation board AN2862

1 Description of the evaluation board

The TS2007FC demonstration board is designed for the TS2007FC class D audio differential amplifier. The TS2007FC device, in a flip-chip package, is mounted on a twolayer PCB. Easily-accessible connectors on the board allow changing or driving the gain select and standby control pins, as well as changing the input configuration of the TS2007FC.

The TS2007FC’s gain can be set to either 6 or 12 dB via the P1 connector (see Tab l e 1 ).

The input configuration is either capacitor-coupled or common-mode feedback. On the evaluation board, the JP3 and JP4 connectors allow you to change the input configuration.

In the capacitor-coupled configuration, the -3 dB cut-off frequency in Hz is:

----------------------------------- -

⋅⋅

2π Z

inC1

----------------------------------- -=

2π ZinC

⋅⋅

with Z

in Ω (Zin=75kΩ typically), C in Farads and C1 = C2.

More information about component calculations is available in the TS2007FC datasheet.

Table 1. Evaluation board connectors

Connector(s) Description

JP1 Input signal connector (GND, In+, In-, GND).

JP1 Output signal connector (GND, Out-, Out+, GND).

Input configuration:

JP3, JP4

– capacitor-coupled when JP3 and JP4 are open. – common-mode feedback when JP3 and JP4 are shorted by jumpers.

Gain select control connector:

– pins 1 and 2 are shorted or pin 2 is floating, the gain is 6 dB.

123

– pins 2 and 3 are shorted, the gain is 12 dB.

123

The connector pins are connected as follows: – 1 to V

– 2 to GS of the TS2007FC – 3 to GND

Standby control connector:

– pins 1 and 2 are shorted, the TS2007FC is in operation mode.

123

– pins 2 and 3 are shorted, the TS2007FC is in standby mode.

123

The connector pins are connected as follows: – 1 to V

– 2 to STANDBY of the TS2007FC – 3 to GND

JP5 Power connector (V

and GND). Power supply voltage from 2.4 to 5.5 V.

Caution: When you apply the power supply through JP5, do not invert the polarity since this will

irreversibly damage the U1 amplifier.

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AN2862 Description of the evaluation board

Figure 1. Schematic diagram

GND

IN IN +

GND

JP1

VCC

1 2

JP3

1 2 3 4

220nF

JP4

A2C2

U1 TS2007

GS Vcc

IN -

Gain

Select

IN +

Standby Control

VCC

Standby Gnd

C3 1uF

Vcc

Oscillator

VCC

PWM

Bridge

Prot ection

Circuit

JP5

1 2

OUT+

OUT-

JP2

GND

OUT+

OUT-

GND

1 2 3

Table 2. Component list for the demonstration board

Designation Quantity Description

C1, C2 2 220 nF/16 V, SMD ceramic capacitors, 0603

C3 1 1 µF/16 V, SMD ceramic capacitor, 0603

JP1, JP2 2 4-pin header 2.54 mm pitch

JP3, JP4, JP5 3 2-pin header 2.54 mm pitch

P1, P2 2 3-pin header 2.54 mm pitch

U1 1 TS2007EIJT

3/7

Demonstration board layout AN2862

2 Demonstration board layout

The following figures depict the top view and layers of the demonstration board.

Figure 2. PCB top layer Figure 3. PCB bottom layer

Figure 4. Top view and dimensions of the demonstration board

4/7

AN2862 Conclusion

3 Conclusion

To order the board online go to http://www.st.com/stonline/domains/buy/buy_dev.htm, and user the order code STEVAL-CCA012V1.

5/7

Revision history AN2862

4 Revision history

Table 3. Document revision history

Date Revision Changes

06-Feb-2009 1 Initial release.

6/7

AN2862

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