ST AN2722 Application note

AN2722

Application note

Demonstration board user guidelines for the

TS4601B high-performance stereo headphone driver

Introduction

This application note concerns the TS4601B’s demonstration board, designed to evaluate the TS4601B, a high-performance stereo headphone driver with capacitor-less outputs and

C interface from STMicroelectronics.

This document provides:

■ a brief description of the TS4601B device.

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

■ a description of the TS4601B control software provided.

■ the layout of the demonstration board.

Figure 1. TS4601B demonstration board

About the TS4601B

The TS4601B is a stereo headphone driver dedicated to high audio performance and space-constrained applications. It is based on a low-power dissipation amplifier core technology. Special care was taken in the design of the amplification chain to achieve peerless PSRR (107 dB typ. at 217 Hz) and 101 dB of SNR.

The TS4601B can drive at minimum 0.9 V 10 kΩ, regardless of the power supply voltage, in the range of 2.9 to 5.5 V.

An I²C interface is used to control the volume through 64 steps ranging from -60 dB to +4 dB and to configure the device in multiple modes. The traditionally-used output-coupling capacitors can be removed and a dedicated common-mode sense pin suppresses parasitic noise from the jack.

The TS4601B is designed to be used with an output serial resistor. It ensures unconditional stability over a wide range of capacitive loads. It is packaged in a tiny 16-bump flip chip package with a pitch of 500 µm and a 300-µm diameter ball size.

March 2009 Rev 2 1/16

output voltage into 16 Ω and 1.6 V

rms

into

www.st.com

The TS4601B has the following key features.

■ Power supply range: 2.9 to 5.5 V

■ 107 dB of PSRR at 217 Hz

■ Fully-differential inputs

■ I²C interface for volume control

■ Digital volume control range from -60 dB to +4 dB

■ 101 dB of SNR A-weighted

■ Independent right and left channel shutdown control

■ Low quiescent current: 4.8 mA typ. at 3.0 V

■ Low standby current: 2 µA max

■ Output coupling capacitors removed

■ Flip-chip package: 2.1 mm x 2.1 mm, 500 µm pitch, 16 bumps

Refer to the datasheet for complete information on the TS4601B.

AN2722

2/16

AN2722 Description of the demonstration board

1 Description of the demonstration board

The TS4601B demonstration board is designed to help you evaluate the TS4601B audio differential input stereo headphone amplifier. The TS4601B device, in a flip chip package, is mounted on a four-layer PCB. An on-board RS-232 to I to control from a personal computer by using its serial port.

The provided software controls all of the TS4601B’s features (gain, mode, mute, standby and register status).

You can use the connectors on the demonstration board to directly control some of the features.

● The master standby of the TS4601B can be set directly by Cn8 or, if the jumper is

removed, by an external digital control (see Ta bl e 1 ).

● By removing the jumpers on Cn6 and Cn7, you can disconnect the on-board I

interface so that you can control the TS4601B by an external I

● The -3 dB cut-off input high-pass filter is set at about 6 Hz (C4 to C7). If you want to

change this frequency, you have to replace C4 to C7 at the same time. More information about these component calculations is available in the TS4601B datasheet.

● The actual current consumption of the TS4601B can be measured directly by removing

the jumper on Cn3 and inserting a DC amperemeter in series. The overall current consumption of the demonstration board is higher than the consumption of the TS4601B because the Cn1 power supply connector supplies the RS-232 to I in addition to the TS4601B.

Table 1. Demonstration board connectors

C interface makes this board easy

C bus interface.

C adapter

Connector Description

Cn1 Power connector (V

Fully-differential positive and negative input signal connectors (active input signal

Cn2, Cn9

Cn3

Cn4 Left output connector (GND and active signal).

Cn5 Right output connector (GND and active signal).

Cn6, Cn7

Cn8

and GND). By shorting one active input to GND, you can use the demonstration board in single-ended input mode (refer to the TS4601B datasheet for more information).

Connector that allows direct measurement of TS4601B’s current consumption. Remove the jumper and insert a DC amperemeter.

SCL and SDA connectors: – pins shorted, TS4601B is controlled by the on-board RS 232 to I – pins unshorted, TS4601B can be controlled by an external I

Standby control connector: – when pins 1 and 2 are shorted, the TS4601B is in operation mode. – when pins 2 and 3 are shorted, the TS4601B is in master standby mode. The connector pins are connected as follows: – pin 1 to V – pin 2 to SDZ of the TS4601B – pin 3 to GND

and GND). Power supply voltage from 2.9 V to 5.5 V.

C bus.

C interface.

3/16

Description of the demonstration board AN2722

Table 1. Demonstration board connectors (continued)

Connector Description

J1 3.5 mm stereo headphone plug.

DB9 female connector enabling connection of the demonstration board to the RS-232 serial port.

Caution: When you apply the power supply through Cn1, do not invert the polarity as this will

damage the U1 amplifier.

4/16

AN2722 Description of the demonstration board

Figure 2. Schematic diagram

VccI2C Vcc

Cn8

Stdby

Vcc

GndP

Cn1

Power

Cn2

Cn9

GndP

Left Input

Right Input

Gnd

Cn3

2.2uF

SDA

SCL

2.2uF

Gnd

GndP

TS4601

InL-

InL+

SDZ

InR+

InR-

SDA

I2C

SCL

PVcc Gnd C1 C2

Vcc

Negative

Supply

A4 A3 A2 A1

1uF

GndP GndPGndP

Cn6

SCL SDA

C1 1uF

Gnd

Vcc

Positive

Negative

PVss

Reg

VoutL

CMS

VoutR

Gnd

2.2nF

C10

2.2nF

Gnd

Cn4

Left Output

Gnd

Cn5

Right Output

Gnd

Cn7

2.2uF

Vcc

TS4601 main application

DB9

8 3

7 2 6 1

GND

DTR

TXD RTS

DSR

SCL

VccI2C

R4 180

U2A

KP1040

R8 2k2

1N4148

BS170

U2B

KP1040

U2C

KP1040

100

GndP GndPGND2

GND2

SDA

GndP

R6 10KR710K

RS232 to I2C converter

5/16

+ 11 hidden pages