AN1368 - Intersil
Contents
1. players cell phones and media applications that require is J11 J12 LIN Audio Input audio switching P J13 J14 RIN Audio Input S1 SPST Switch for SEL2 S2 SPST Switch for SEL1 HJ1 Stereo Headphone Jack DC POWER SUPPLY 3 3V LOGIC CONTROL AUDIO SOURCE SIGNAL LEFT RIGHT CHA AUDIO SIGNAL OSCILLOSCOPE te CHB capone f oe eto R T U cama RE 1 x ros iia 6 ew V e R3 C da 8 F 00 main m t nO LU 20 2 _ IN Los eye m 1SL54406EVALIZ ROUT REV A ntersii a y 1 888 INTERSIL FIGURE 2 BASIC EVALUATION TEST SETUP BLOCK DIAGRAM 3 intersil AN1368 0 August 18 2008 Application Note 1368 Using the Board Refer to Figure 2 Lab Eguipment The eguipment external supplies and signal sources needed to operate the board are listed below 1 2 3 4 2 7V to 3 6V DC Power Supply Audio Signal Generator Audio Signal Oscilloscope Logic Control Generator and or Pulse Generator Initial Board Setup Procedure ile Attach the evaluation board to the DC power supply at J1 V and J2 GND Positive terminal at J1 and negative terminal at J2 The supply should be capable of delivering 2 7V to 3 6V and 100A of current Set the supply voltage to 3 3V Connect the Audio Source Signal to the LIN and RIN BNC inputs J11 and J13 respectively The analog input voltage range should not exceed2. 1 5VpEAK Connect the Audio Signal Oscilloscope to the LOUT and ROUT BNC outputs J5 and J7 respectively Connect the Logic Control generator to the SEL1 and SEL2 logic inputs Audio Mode 1 With the DC power supply turned on drive SEL1 and SEL2 to Logic 1 gt 1 4V Select the desired load on the board using jumpers JP1 and JP2 or through external loading The audio switches are turned on and the audio inputs at LIN and RIN should be seen at the LOUT and ROUT Click and Pop Mode 1 Drive SEL1 to Logic 1 and drive SEL2 to Logic O or float SEL2 The audio switch is now turned off There is a 400 impedance to ground at the LIN and RIN inputs There is a 6Q impedance to ground at the LOUT and ROUT outputs Mute Mode 1 Drive SEL1 to Logic 0 or float SEL1 and drive SEL2 to Logic 1 2 The audio switch is now turned off There is a 60 impedance to ground at the LOUT and ROUT outputs Shutdown Mode 1 Drive SEL1 to Logic 0 or float SEL1 and drive SEL2 to Logic 0 or float SEL2 The audio switch is now turned off The LIN and RIN terminals are now high impedance The LOUT and ROUT have an impedance of 220kQ in parallel with the output load impedance 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 DESC
3. SEL1 1 SEL2 0 If SEL1 is Logic 1 and SEL2 is Logic 0 the part will go into Click and Pop Mode This mode is optimal when powering up or down the DC biased source inputs or muting the signal to the load In Click and Pop Mode the 2 5Q audio switches are OFF high impedance The Audio Output connections are shunted to ground through 60 resistors that are internal to the IC and the Audio Input connections are shunted to ground through 40Q resistors that are internal to the IC Click and Pop circuitry is active Before powering down or powering up of a DC biased source input the ISL54406 should be put in the Click and Pop Mode In Click and Pop Mode transients generated at the Audio Input connections due to a DC step voltage at the audio source drivers will not pass to the load thus eliminating Click and Pop noise AUDIO MUTE MODE SEL1 0 SEL2 1 If SEL1 is Logic 0 and SEL2 is Logic 1 the part will be in the Audio Mute Mode In the Audio Mute Mode the audio switches are OFF high impedance the Audio Input Click and Pop shunt circuitry is inactive high impedance and the Audio Output connections are shorted through 60 resistors to ground internal to the IC In Audio Mute Mode the ISL54406 IC has excellent Off Isolation for high performance muting of audio signals SHUTDOWN MODE SEL1 SEL 0 If SEL1 and SEL2 pins are Logic 0 the device will enter a low powered Shutdown Mode In SHDN
4. the ISL54406 should be placed in Click and Pop mode before the audio source is turned on or off This allows any transients generated by the source to be discharged through the Click and Pop circuitry first With a typical DC blocking capacitor of 200uF and the Click and Pop circuitry designed to have a impedance of 40Q allowing a 100ms dead time in Click and Pop mode for discharging a transient when entering or leaving Audio Playback mode will eliminate the DC transient generated by the blocking capacitor 2 intersil AN1368 0 August 18 2008 Application Note 1368 V SUPPLY SERIES RESISTOR Board Component Definitions The ISL54406 evaluation board has an optional 1000 series resistor on the V supply line This resistor and the power m DESIGNATOR DESCRIPTION supply decoupling capacitance form a low pass filter that improves PSRR of the ISL54406 Because the ISL54406 IC U1 ISL54406IRUZ IC current draw is small the power dissipation and voltage drop J1 V Positive Connection due to the 1000 series resistor is minimal If the user desires J2 GND Connection to have the series resistor simply remove jumper JP4 J3 J4 SEL2 Logic Input Applications E E ar I 5 LOUT Audi tput The main purpose of the ISL54406 device is to eliminate the iii Click and Pop transients generated by single supply audio J7 J8 ROUT Audio Output codecs and to be used as an audio mute switch for MP3 J9 J10 SEL1 Logic Input
5. RIPTIONS DESIGNATOR DESCRIPTION TP1 V Test point TP2 Ground Test Point TP3 SEL2 Test Point TP4 LOUT Test Point TP5 ROUT Test Point TP6 SEL1 Test Point TP7 RIN Test Point TP8 LIN Test Point 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 4 intersil AN1368 0 August 18 2008 8002 81 1sn6ny O S9ELNV Sisu Board Schematic HEADPHONE JACK GND 89 L S10N uongeonddy
6. aluation board to evaluate the ISL54406 device for Click and Pop elimination and Audio Muting applications Features e Selectable Output Resistive Loads and Input DC Blocking Capacitors RCA Audio Input Output Jacks Stereo Headphone Output Jack and BNC Connectors e Convenient Test Points and Connections for Test Equipment Click and Pop Elimination Circuitry High Off Isolation Audio Muting ISL54406EVAL1Z Evaluation Board User s Manual AN1368 0 August 18 2008 Picture of Evaluation Board Top View FIGURE 1 ISL54406EVAL1Z EVALUATION BOARD Board Architecture Layout Basic Layout of Evaluation Board Refer to Figure 1 and the Board Schematic at the end of this manual The basic layout of the main board is as follows Power J1 Ground J2 logic SEL1 J9 J10 and logic SEL2 J3 J4 connections are located at the top of the board Audio Input BNC RCA connectors are at the right side of the board for LIN input J11 J12 and RIN input J13 J14 Note The audio inputs have a 200uF series DC blocking capacitance that can be used for AC coupling audio signals that are DC biased in single supply systems If the audio source is not DC biased it is recommended to bypass the capacitors C3 to C6 by placing a jumper on JP6 for LIN and JP7 for RIN Note that if the audio source already has a DC blocking capacitor it is recommended to bypass the capacitor on the evaluation board otherwise this will increase ins
7. ertion loss The capacitance can be reduced to 100HF by depopulating the 0 resistor on Rg and R7 Audio output RCA BNC connectors are on the left side of the board labeled LOUT output J5 J6 and ROUT output J7 J8 In addition the left and right outputs are also connected to the stereo headphone jack HJ1 Selectable load resistances are available on the evaluation board When jumpers JP2 and JP3 are in the 1 2 pin position the load is 20kQ and in the 2 3 position the load is 3202 The load can be bypassed by removing the jumpers altogether Located in the center of the board is the ISL54406 IC U1 The socket for the IC has a pin 1 dot to show how the IC should be oriented on the socket The IC pin 1 indicator dot needs to be aligned with the socket pin 1 indicator dot that is visible when the socket is unlatched 1 CAUTION These devices are sensitive to electrostatic discharge follow proper IC Handling Procedures 1 888 INTERSIL or 1 888 468 3774 Intersil and design is a registered trademark of Intersil Americas Inc Copyright Intersil Americas Inc 2008 All Rights Reserved All other trademarks mentioned are the property of their respective owners Application Note 1368 Power Supply The DC power supply connected at banana jacks J1 V and J2 GND provides power to the evaluation board The IC requires a 2 7V to 5 0V DC power supply for proper operation although the recommended range is 2 7V to 3 6V The power sup
8. intersil Application Note Description The ISL54406EVAL1Z evaluation board is designed to provide a quick and easy method for evaluating the ISL54406 Click and Pop Eliminator IC The ISL54406 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 FN6578 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 is the best way to get a quick understanding of how the part works A picture of the evaluation board is shown in Figure 1 The ISL54406 HTGFN IC is set in a socket on the evaluation board It is located in the center of the board and is designated as U1 The ISL54406 IC is a dual SPST analog switch that has four modes of operation Audio Mute Click and Pop and Shutdown SHDN mode The evaluation board contains standard RCA BNC connectors and a single headphone jack to allow the user to easily interface with the IC to evaluate its functions features and performance in the four modes of operation The evaluation board has selectable output loads of 20kQ and 320 resistors to simulate an audio amplifier pre amp or stereo headphones The board also has DC blocking capacitors at the switch input to remove the DC bias of single supply amplifiers This application note will guide the user through the process of configuring and using the ev
9. ply should be capable of delivering 100 A of current Logic Control The state of the ISL54406 device is determined by the voltage at the SEL1 J9 J10 and the SEL2 J3 J4 inputs Normally jumpers JP1 and JP5 should be in the 1 2 pin position If the user desires to control the logic state of SEL1 and SEL2 via switches S1 and S2 on the board place jumpers JP1 and JP5 in the 2 3 pin position In the switch up position SEL1 and SEL2 will be tied to V Logic 1 In the down position a 4MO resistor internal to the IC will pull SEL1 and SEL2 to GND Logic 0 These control pins are 1 8V logic compatible which allows for control via a standard ucontroller Logic 0 LOW when lt 0 5V or floating Logic 1 HIGH when gt 1 4V Logic States The ISL54406 has four modes of operation that are determined by the SEL1 and SEL2 logic states Audio Playback Mode Click and Pop Mode Audio Mute Mode and Shutdown SHDN Mode AUDIO PLAYBACK MODE SEL1 SEL2 1 If the SEL1 and SEL2 pins are Logic 1 the part will be in the Audio Playback mode In Audio Playback mode the LIN and RIN pins are connected to the LOUT and ROUT pins respectively through a 2 50 switch path The Audio Inputs have a selectable 100uF or 200uF series DC blocking capacitor or can be bypassed altogether The Audio Outputs can be loaded on the evaluation board with a 320 or a 20kQ resistor or can be bypassed altogether CLICK AND POP MODE
10. the audio switches are OFF the 60 path is high impedance the Click and Pop circuitry is inactive and the device will draw a minimal amount of current Note When the logic inputs are floated the ISL54406 will automatically be placed in SHDN mode due to the internal 4MQ pull down resistors on the logic pins Note Off Isolation performance is degraded when the device is placed into SHDN The design of the ISL54406 optimizes low current consumption in SHDN Mode compromising Off Isolation performance Thus SHDN Mode should not be used for muting audio if Off Isolation is a concern Note The ISL54406 should not be brought into Audio Playback mode directly from Shutdown mode A DC transient may occur at the LOUT ROUT pins when brought from Shutdown directly to Audio Playback mode The recommended procedure is to place the ISL54406 into Mute mode for at least 100ms when entering or leaving Audio Playback mode CLICK AND POP OPERATION Single supply audio sources are biased at a DC offset that generates transients during power on off of the audio source This DC offset is coupled through a blocking Capacitor causing a transient voltage at the load When the source is off and suddenly turned on with a DC offset the capacitor will develop a voltage equal to the DC offset If the ISL54406 is in Audio mode a transient discharge will occur in the speaker generating a Click and Pop noise For proper operation of Click and Pop elimination
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