®

ISL54206AEVAL1Z Evaluation

Board User’s Manual

July 31, 2007 AN1337.0

Application Note

Description

The ISL54206AEVAL1Z evaluation board is designed to provide a quick and easy method for evaluating the

ISL54206A USB/Audio Switch IC.

The ISL54206A device is a unique IC. To use this evaluation board properly requires a thorough knowledge of the operation of the IC. Refer to the data sheet for an understanding of the functions and features of the device.

Studying the device’s truth table along with its pinout diagram on page 2 of the data sheet FN6515 is the best way to get a quick understanding of how the part works.

A picture of the main evaluation board is shown in Figure 1.

The ISL54206A µTQFN IC is soldered onto the evaluation board. It is located in the center of the board and is designated as U1.

The ISL54206A IC has two modes of operation called Audio mode and USB mode. The evaluation board contains standard Audio and USB connectors to allow the user to easily interface with the IC to evaluate its functions, features and performance in the two modes of operation. For example, when the board is properly powered, a headphone can be plugged into the headphone jack (J7) and a stereo source (such as an MP3 player) can be connected at the

RCA connectors J3 (AUDIO LEFT) and J4 (AUDIO RIGHT) to play music through the audio switches of the IC. See

Figure 2. You can then turn-off the audio source, remove the

headphones and attach a USB cable from a computer to the

USB connector J1 (USB TO HOST). This will establish a connection from the computer through the USB switches of the IC to the USB device connected at the USB connector J2

(USB TO DEVICE), to send and receive data.

This application note will guide the user through the process of configuring and using the evaluation board to evaluate the

ISL54206A device in both the Audio mode and the USB mode.

Features

• Standard USB Connectors

• RCA Audio Input Jacks and Headphone Speaker Jack

• Convenient Test Points and Connections for Test

Equipment

Picture of Evaluation Board (Top View)

FIGURE 1. ISL54206AEVAL1Z EVALUATION BOARD

Board Architecture/Layout

Basic Layout of Evaluation Board

The basic layout of the main board is as follows: Refer to

Figure 1.

Power and Ground connections are at the top of the board

(J10 and J11).

Logic control connections are at the top of the board (J12 and J13).

Audio Source Inputs are at the lower right side of the board

(J3 to J6). Audio outputs are at the lower left side of the board (J7, J8, J9). Connector J7 is a standard headphone jack for connecting a 32

Ω headphone.

USB connection to an upstream host controller (Computer) is made at connector J1, located on left underside of the board. USB connection to a downstream USB device is made at connector J2, located on right underside of the board.

Located in the center of the board is the ISL54206A IC (U1).

The eval board has a pin 1 dot, to show how the IC should be oriented on to the evaluation board. The IC pin 1 indicator dot needs to be aligned with the evaluation board pin 1 dot indicator.

1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

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Application Note 1337

Power Supply

The DC power supply connected at banana jacks J10 (VDD) and J11 (GND) provides power to the part. The IC requires a

2.7V to 5.5V DC power supply for proper operation. The power supply should be capable of delivering 100µA of current.

Logic Control

The state of the ISL54206A device is determined by the voltage at the IN pin and the CTRL pin.

Access to the CTRL pin is through the banana jack J12

(CTRL).

Access to the IN pin is through banana jack J13 (IN) when jumper JP3 is in position 2 to 3 and through the USB J1

(USB TO HOST) connector V

BUS

line when the jumper JP3 is in position 2 to 1.

These control pins are 1.8V logic compatible, which allows for control via a standard microcontroller.

Logic “0” (LOW) when

≤ 0.5V

Logic “1” (HIGH) when

≥ 1.4V

Note: The evaluation board has the option of putting a 4M

Ω pull-down resistor from the IN pin to ground by putting a jumper at JP4. The CTRL pin has an internal 4M

Ω pull-down resistor. These resistors pull the logic pins to ground when

J13, J1, or J12 are floated.

If IN is driven LOW and CTRL is HIGH, the part will be in the

Audio mode. The audio switches will be ON and the USB switches will be OFF.

If IN is driven HIGH and CTRL = X (don’t care), the part will be in the USB mode. The USB switches will be ON and the audio switches will be OFF.

If IN is LOW and CTRL = LOW, the part will be in the Low

Power mode. In Low Power mode all switches are OPEN and the part will draw around 1nA of current.

SETTING UP THE EVALUATION BOARD TO USE THE

COMPUTER V

BUS

VOLTAGE TO DRIVE THE “IN’ PIN

Rather than using a logic controller to control the IN logic pin through the J13 (IN) banana jack, you can directly drive the

IN pin using the V

BUS

voltage from the computer through the

USB J1 (USB TO HOST) connector.

To control the part through the J1 connector make the following connections:

1. Install jumper at JP4. This connects an external 4M

Ω resistor from the IN pin of the part to ground.

2. Install jumper at location 2 to 1 of jumper JP3. This connects the V

BUS

line of the J1 USB connector to the IN pin of the part. Note: With the jumper in this position, the

J13 banana jack is no longer connected to the IN pin of the part.

When the computer is not connected at J1, the external pull-down will pull the IN pin low, putting the ISL54206A in the Audio mode or Low Power mode depending on the condition of the CTRL pin.

When a USB cable from the computer is connected at J1, the voltage at the IN pin will be driven to 5V and the part will automatically go into the USB mode.

When the USB cable is disconnected from the J1 connector, the voltage at the IN pin will be pulled low by the pull-down resistor and return to the Audio Mode or Low Power Mode, depending on the condition of the CTRL pin.

Note: The voltage at the IN pin can exceed the VDD voltage by as much as 2.55V. This allows the V

BUS

voltage from a computer or USB hub (4.4V to 5.25V) to drive the IN pin while the V

DD

voltage is in the range of 2.7V to 5.5V.

Audio Inputs

The evaluation board has two audio inputs labeled AUDIO

LEFT (J3 or J5) and AUDIO RIGHT (J4 or J6). Each of these inputs have a BNC connector wired in parallel with a RCA jack connector. You can connect an audio source/generator at either the BNC connector or the RCA connector.

In a typical application, the left and right outputs of a stereo source, such as an MP3 player, would be connect to the

RCA jacks J3 and J4, respectively.

Over a signal range of

±1V (0.707V

RMS

) these switches have an extremely low r

ON

resistance variation. They can pass ground referenced audio signals with very low distortion (<0.05% THD+N) when delivering 15.6mW into a

32

Ω headphone speaker load. A 3V

P-P

signal is acceptable but performance will degrade.

The audio channels are AC coupled with 100µF capacitors.

These caps remove any DC voltage from the audio signals and reference them to ground of the device. If the audio source being connected to the evaluation board already has internal AC coupling capacitors at the output of its drivers then the capacitors on the evaluation board should be shorted out (replaced with 0

Ω resistors). This will prevent further attenuation of the low frequency content of the audio signal due to the increase of the high-pass corner frequency resulting from the evaluation board capacitor in series with the audio source capacitor.

Note: When in USB mode, the audio source needs to be in a high impedance state so it will not interfere with the USB signal. Since the audio source inputs are AC coupled on the evaluation board, simply turning the audio source OFF will isolate it from interfering with the USB signal.

Audio Outputs

The evaluation board has a standard headphone jack labeled HEADPHONE JACK (J7). A 32

Ω stereo headphone should be plugged into this jack.

The BNC connector J8 (COM-) is in parallel with the audio left line of the headphone jack and the D- line of the J1 (USB

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Application Note 1337

To HOST) connector. The BNC connector J9 (COM+) is in parallel with the audio right line of the headphone jack and the D+ line of the J1 (USB To DEVICE) connector. These

BNC connectors can be used to connect resistive loads and/or test equipment to evaluate the performance of the IC.

USB Connections

A “B” type USB receptacle labeled “USB TO HOST” (J1) is located on the left underside of the board. This receptacle should be connected (using a standard USB cable) to the up-stream USB host controller which, is usually a PC computer or hub. When this connection is made and the IN logic control is driven HIGH, the ISL54206A device will go into USB mode. The USB switches will be turned ON.

An “A” type USB receptacle labeled USB TO DEVICE (J2) is located on the right underside of the board. The USB device can be plugged directly into this receptacle or through a standard USB cable.

In USB mode, the USB host controller and the USB device will be connected through the internal USB switches of the

IC. The USB switches are bi-directional, which allows the host (computer) and downstream USB device to both send and receive data.

Note: Before connecting the USB host controller at connector J1, the headphones must be removed from the headphone speaker jack, J7. This will prevent the audio load from interfering with USB signal transmission. The main purpose of the ISL54206A device is to allow the use of a common USB and Audio Headphone Connector in Personal

Media Players and other portable battery powered equipment. Either a headphone will be in the common connector to play music or a USB cable from a computer will be in the common connector to transmit digital data, such as music, into the memory of the Media Player.

The BNC connector J8 (COM-) is in parallel with the D- line of the J1 USB connector. The BNC connector J9 (COM+) is in parallel with the D+ line of the J1 USB connector.

The BNC connector J14 (D-) is in parallel with the D- line of the J2 USB connector. The BNC connector J15 (D+) is in parallel with the D+ line of the J2 USB connector. If you want to use the J14 and J15 BNC connectors, you must populate

R

1

and R

2

with 0

Ω resistors. These BNC connectors can be used to connect test equipment to evaluate the performance of the IC.

Board Component Definitions

DESIGNATOR

U1

DESCRIPTION

ISL54206AIRUZ IC

J1

J2

“B” type USB Receptacle

“A” type USB Receptacle

J3, J5

J4, J6

J7

J8

Left Stereo Audio Input

Right Stereo Audio Input

Headphone Speaker Jack

COM- BNC Connector

J9

J10

J11

J12

J13

J14

J15

JP1, JP2

JP3

JP4

COM+ BNC Connector

VDD Positive Connection

VDD Negative Connection

CTRL Logic Control

IN Logic Control

D- BNC Connector

D+ BNC Connector

D-/D+ Differential Probe Connection

IN Pin Connector Selection

Jumper Position 2 to 3 Control through J13

Jumper Position 2 to 1 Control through J1

Connect 4M

Ω Pull-down Resistor to IN Pin

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Application Note 1337

COMPUTER

USB PORT

Using The Board (

Refer to Figure 2

)

Lab Equipment

The equipment, external supplies and signal sources needed to operate the board are listed below:

1. +3V to 5V DC Power Supply

2. Stereo Audio Source (MP3/Radio/CD Player) or Audio

Generator

3. Headphone Set or Audio Analyzer/Oscilloscope

4. Two standard USB cables

5. Computer with USB port

6. USB device (i.e. USB memory stick, MP3 Player with

USB port, etc.)

Initial Board Setup Procedure

1. Attach the main evaluation board to a DC power supply at J10 (VDD) and J11 (GND). Positive terminal at J10 and negative terminal at J11. The supply should be capable of delivering 3V to 5V and 100µA of current. Set the supply voltage to 3.3V.

2. Connect the stereo audio source left channel to J3 RCA connector or J5 BNC connector and the right channel to

J4 RCA connector or J6 BNC connector.

3. Connect the USB device to the USB “B” type receptacle,

J2 (USB TO DEVICE).

Audio Mode Operation

1. Install headphone in the headphone jack, J7. No USB cable should be connected at the J1 (USB TO HOST) connector.

DC POWER

SUPPLY

+3.3V

+

-

LOGIC

CONTROL

IN

JP4

J13

VDD GND

J10

JP3

USB TO HOST

J1

JP2

3 2 1

U1

J11

JP1

J14

CTRL

J12

USB

TO

DEVICE

J2

J15

J7

HEADPHONE

JACK

J8 J9

J5

AUDIO LEFT

J3

COM - COM +

J6

AUDIO RIGHT

ISL54206AEVAL1Z EVALUATION BOARD

J4

FIGURE 2. BASIC EVALUATION TEST SETUP BLOCK DIAGRAM

L

R

USB DEVICE

USB PORT

AUDIO

SOURCE

2. Logic Control: Put CTRL = Logic “1” and IN = Logic “0”.

You will now be in Audio mode (3

Ω audio switches are

ON).

3. Turn the audio source ON. You should hear the music in the headphones.

4. You can observe the audio signals at the output of the IC on an oscilloscope or audio analyzer by using the J8 and

J9 BNC connectors. Connect to J8 for Left audio and J9 for right audio.

USB Mode Operation

1. Turn OFF audio stereo source.

2. Remove headphone from J7 Headphone Jack.

3. Logic Control: Put CTRL = Logic “X” and IN = Logic “1”.

You will now be in USB mode (5

Ω audio switches are

ON).

4. Connect USB cable from computer USB port to the USB

“A” type receptacle, J1 (USB TO HOST) on the evaluation board. The computer should indicate that it is connected to the USB device connected at the J2 connector.

5. You will now be able to send and receive data between the computer and USB device.

6. You can observe the D- and D+ USB digital signals on an oscilloscope or other test equipment by connecting to the

J8, J14, J9 and J15 BNC connectors or various test

points located on the board (see “Test Points” on page 5).

7.

Remove the 0

Ω resistors R

1

, R

2

, R

3

, R

4

when evaluating the performance (i.e. eye diagram, etc.) of the high speed

USB signal.

Removal of these resistors disconnects the headphone jack (J7) and BNC connectors (J8, J9, J14,

J15) from the USB differential lines. These components

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Application Note 1337

(when connected) will degrade the USB signal. These components will not be there in an actual application.

Note: R

3

and R

4

are located on the underside of the board.

If you disconnect the USB cable from J1 and take the IN pin

LOW, the IC will return to Audio mode. You can now plug the headphone set into headphone jack, turn the audio source

ON to once again play music.

Test Points

The board has various test points for ease of connecting probes to make measurements. The test points available are

described in Table 1.

TABLE 1. TEST POINT DESCRIPTIONS

DESIGNATOR DESCRIPTION

TP1 V

DD

test point

TP2, TP6, TP7,

TP8, TP9

Ground Test Point

TP3

TP4

V

BUS

Test Point

Audio Left Input Test Point

TP5

JP1

JP2

Audio Right Input Test Point

D-/D+ Differential Probe Connection - USB Device

Side of Switch

D-/D+ Differential Probe Connection - COM Side of Switch

Board Schematic

NOTE:

The 4M

Ω pull-down resistor (R

5

) was added to the eval board to allow control of the IN pin through the J1 connector by the V

BUS voltage from the computer. By connecting a jumper at JP4 and JP3 (position 1 to 2), control of the ISL54206A IN pin will be through the J1 USB Connector. When you connect the computer at J1, the IN pin will be pulled high by V

BUS

voltage from the computer.

When the computer is disconnected, the IN pin will be pulled low by the pull-down resistor.

Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that the Application Note or Technical Brief is current before proceeding.

For information regarding Intersil Corporation and its products, see www.intersil.com

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July 31, 2007