ST AN2933 APPLICATION NOTE

AN2933

Application note

Demo board user guidelines for the TS4999 filter-free stereo

2 x 2.8 W class D audio power amplifier with selectable 3D effect

Introduction

This application note concerns the TS4999 demonstration board, designed to evaluate the stereo class D audio differential amplifier TS4999.

This document provides:

■ a brief description of the TS4999 device.

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

■ the layout of the demonstration board.

About the TS4999

The TS4999 is a fully-differential class D stereo power amplifier. It can drive up to 1.35 W into an 8 Ω load at 5 V per channel. The device has four different gain settings utilizing two discrete pins, G0 and G1.

Pop and click reduction circuitry provides low on/off switch noise while allowing the device to start within 8 ms. 3D enhancement effects are selected through one digital input pin that allows more amazing stereo audio sound.

Two standby pins (active low) allow each channel to be switched off separately.

The TS4999 is available in an 18-bump flip-chip package.

Key features of the TS4999

■ Operating range from V

■ Dedicated standby mode active low for each channel.

■ Output power per channel: 2.8 W at 5 V into 4 Ω with 10% THD+N or 0.7 W at 3.6 V into

8 Ω with 1% THD+N max.

■ Selectable 3D sound effect.

■ Four gain setting steps: 3.5, 6, 9.5 and 12 dB.

■ Low current consumption.

■ PSRR: 63 dB typical at 217 Hz.

■ Fast start-up phase: 7.8 ms.

■ Output short-circuit and thermal shutdown protection.

■ Flip-chip 18-bump lead-free package.

Refer to the datasheet for complete information on the TS4999.

= 2.4 V to 5.5 V.

March 2009 Rev 1 1/10

www.st.com

Description of the demonstration board AN2933

1 Description of the demonstration board

The TS4999 demonstration board is designed to evaluate the TS4999, a fully-differential class D stereo power amplifier. The TS4999 device, in a flip-chip package, is mounted on a four-layer PCB. Easily-accessible connectors on the board allow changing or driving the gain select pins (G0 and G1), the standby control pins for the left and right channels (STBL and STBR) and the 3D sound effect pin (3D).

The differential gain of the TS4999 can be set to 3.5, 6, 9.5, or 12 dB, depending on the logic level of the G0 pin (connected to pin 2 of S1) and G1 pin (connected to pin 2 of S2).

Table 1. Gain settings with G0 and G1 pins

G1 G0 S1 S2 Gain (dB) Gain (V/V)

00 3.51.5

01 62

10 9.53

11 124

123

Note: An internal 300 kΩ (+/-20%) resistor is placed between pins G0, G1 and GND. When the

pins are floating (S1 and S2 included), the gain is 3.5 dB. In full standby (left and right channels OFF), these resistors are disconnected (HiZ input).

Table 2. Truth table for 3D effect pin and STANDBY pins

3D STBYL STBYR 3D Effect Left channel Right channel

0 0 0 X STDBY STDBY

001OFFSTDBYON

010OFFONSTDBY

011OFFONON

1 0 0 X STDBY STDBY

1 0 1 N/A N/A N/A

1 1 0 N/A N/A N/A

1 1 1 ON ON ON

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AN2933 Description of the demonstration board

Note: 1 An internal 300 kΩ (+/-20%) resistor is placed between pins STBYL, STBYR, 3D and GND.

When the 3D pin is floating (S5 included), the 3D effect is switched off. When pins STBYL, STBYR are floating (S3 and S4 included), the amplifier is in full standby mode. In full standby (left and right channels OFF), the internal resistors of the gain and 3D effect pins (G0, G1 and 3D) are disconnected (HiZ input).

2 When the 3D effect is switched on, both channels must be in operation or in shutdown mode

at the same time.

The amplifier’s inputs are capacitor-coupled, meaning that the -3 dB cut-off frequency F Hz is:

with Z

in Ω, Cin in Farads, C1 = C2 and C3 = C4.

3 On the TS4999 demonstration board, C

impedance Zin changes with the set gain, as does F

⋅⋅

2π Z

inCin

= C1 = C2 = C3 = C4 = 220 nF. The input

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

More information on component calculations is available in the TS4999 datasheet.

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Description of the demonstration board AN2933

Table 3. Demonstration board connectors

Connector(s) Description

P1 Power connector (V

Gain setting connectors: S1 for the G0, S2 for the G1 pin of the TS4999.

The pins are connected as follows: – 1 to V

– 2 of S1 to the G0 pin

S1, S2

– 2 of S2 to the G1 pin – 3 to GND Jumper position: – logical "1": pins 1 and 2 are shorted – logical "0": pins 2 and 3 are shorted

Standby control connector: S3 for the left channel, S4 for the right channel. The pins are connected as follows: – 1 to V

– 2 of S3 to the STBYL pin of the TS4999

S3, S4

– 2 of S4 to the STBYR pin of the TS4999 – 3 to GND Jumper position:

– pins 1 and 2 are shorted, the channel is operating.

123

– pins 2 and 3 are shorted or pin 2 is floating, the channel is in standby

123

mode.

3D effect control connector. The pins are connected as follows:

– 1 to V – 2 to 3D pin of the TS4999

– 3 to GND

– pins 1 and 2 are shorted, the 3D effect is ON.

123

– pins 2 and 3 are shorted, the 3D effect is OFF.

123

JP1

Left channel input signal connector (GND, L

and GND). Power supply voltage from 2.5 to 5.5 V.

123

+, Lin- and GND)

JP2

JP3

Right channel input signal connector (GND, R

Left channel output signal connector (GND, L

JP4 Right channel output signal connector (GND, R

-, Rin+and GND)

+, Lo- and GND)

-, Ro+and GND)

Caution: When you apply the power supply through P1, do not invert the polarity since this will

irreversibly damage the U1 amplifier.

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AN2933 Description of the demonstration board

Figure 1. Schematic diagram

Vcc

P1 Vcc

Lin+

Lin-

GND

123

JP1

220nF

VCC

220nF

123

JP2

Rin+

Rin-

GND

LinP

LinN

RinP

RinN

S3 STBL

VCC VCC

Lin+

Lin-

Rin+

Rin-

STBYL

STBL

STBYR

STBR

TS4999 - FC18

S4 STBR

Gain

Select

Gain

Select

VCC

Standby

Control

C5 100nF

PWM

Vcc

RPVCC

C6 1uF

LPVCC

Bridge

C7 1uF

Lout+

Lout-

JP3

1 2 3 4

Header 4

S5 3D

C13D

AVCC

Oscillator

3D EFFECT

PWM

Bridge

Rout+

Rout-

JP4

1 2 3 4

Header 4

Protection

Circuit

PGNDAGND

Table 4. Component list for the demonstration board

Designation Quantity Description

C1, C2, C3, C4 4 220 nF/16 V, SMD ceramic capacitor, 0603

C5 1 100 nF/16 V, SMD ceramic capacitor, 0603

C6, C7 1 1 µF/16 V, SMD ceramic capacitor, 0603

P1 1 2-pin header 2.54 mm pitch

S1, S2, S3, S4, S5 5 3-pin header 2.54 mm pitch

JP1, JP2, JP3, JP4 4 4-pin header 2.54 mm pitch

U1 1 TS4999 class-D audio amplifier

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Demonstration board layout AN2933

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 middle layer 1

Figure 4. PCB middle layer 2 Figure 5. PCB bottom layer

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AN2933 Demonstration board layout

Figure 6. Top view and dimensions of the demonstration board

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Conclusion AN2933

3 Conclusion

To order the board online, go to http://www.st.com/stonline/domains/buy/buy_dev.htm, and use the order code STEVAL-CCA016V1.

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AN2933 Revision history

4 Revision history

Table 5. Document revision history

Date Revision Changes

27-Mar-2009 1 Initial release.

9/10

AN2933

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