I need help interpreting the TS5USBA224 (integrated USB 2.0 and analog audio switch) datasheet.

Ranita,

The TS5USBA224 is a passive, bi-directional, FET switch.  This device is designed to select two different signals and simply pass the signal from one side of the switch to the other without degrading signal integrity.  If you were to have an ideal model of the signal path it would be a 0 ohm wire. 

1) Audio Switch:

Oiso=-83dB, it means the effect of USB D+/D- signal on the audio channel when USB communication is ongoing. Right?

Xtalk=-83dB here means the crosstalk between left and right channel?

Both specs are taken at 20kHz frequency point?

You can see the descriptions of how the parameters are measured in the parameter measurement section in the datasheet.  The Oiso measurement is off isolation which describes the IC's ability to isolate the signal path when it is not selected.  For example if there is a signal on the D+ and the audio path is selected this measurement describes how well the IC isolates the D+ signal from the D+/R path. 

The Xtalk measurement does mean how much of the signal gets coupled onto an adjacent channel.  We know there is an error in the datasheet that the audio path cross talk measurement is not taken over the audio band.  We just designed hardware to take this measurement again and should have a revised version of the datasheet in a couple weeks.

 

2) USB Switch:

Oiso=-22dB, it means the effect of Audio L/R signal on the USB channel when audio signal is on transferring. Right?

Xtalk=-21dB here means the crosstalk between D+ and D- channel?

Both specs are taken at 240kHz frequency point?

The off isolation Oiso spec means the amount of signal passing through the switch from the unselected channel. 

The cross talk spec describes the amount of signal coupling onto the adjacent channel either L/R pins or D+/D-. 

 

3) When chip is operating, does  D+/R pin output DC level? How much the value?

This is a passive device there the TS5USBA224 does not provide any DC output.  If you require a DC offset in your system you will need to provide it externally to the switch IC.

4) When audio input via USB connector, need  insert  coupler capacitor  between D+/R pin and audio source?

 This will depend on the system requirements of your audio codec.  The TS5AUSB224 device does not require any external components.  The only design requirement is that the signals on the device must be within the recommend operating conditions. 

I you would like to a reference design of using audio signals through the USB type C connect you can take a look at the materials in this post.

From datasheet, VR, VL range, there should be DC at D+/R pin.

Voltage on the L and R pins of the TS5USBA224 device can range from Vaudio (IC supply voltage) to Vaudio-5.5V.  For example if your Vaudio (supply voltage) is running off of a 3.3 V rail you may have a signal on the L R and D+/R pins from -2.2 V to 3.3V.  Most audio codecs have an out that is AC coupled so the audio signals are centered around 0V.  This device is designed to handle the negative signals. 

 

5) From internal block, this switch doesn't have an internal charge pump, will not support a signal swing over the supply voltage, so that means D+/R pin can only be positive signal. Right?

That is correct.  The TS5USBA224 does not have an internal charge pump.  The TS5USBA224 device can handle the negative signaling because it uses a transmission gate. 

Here is a related post on the negative signaling. 

Thank you,

Adam

Nicole,

This device is designed specifically to switch analog audio signals and USB 2.0 signals so you should not have issue with the D+/D- signals coupling onto the audio path from inside the TS5USBA224. Many customer's use this device in many applications that have usb ports like mobile phones and computers.

The big difference in cross talk measurements for the USB switch and the audio switch is intentionally created by design. As I stated before the cross talk is measured between adjacent channels. For an Audio switch you would want excellent cross talk and isolation performance between the L and R channels but for a differential signal on the D+/D- pins you actually want to the signals to couple to help cancel out noise.

Thank you,
Adam