Hi all.
I am working a project and want to take analog audio data from an FM receiver and output through a USB. I will also be using the same USB for uploading data to the esp32 and charging a lipo battery. The TS5USBA224 seems to be made for that purpose! but I have questions.
Vaudio is the power pin to the IC. I was wanting to keep that high (pullup resistor) all of the time and then use VBUS and ASEL to toggle between audio and data.
However, this is a battery-powered application and I want to keep current consumption as low as possible when there is no usb connected. The data sheet says:
"IOFF Supports Partial Powerdown Mode"
But looking at the electrical characteristics of the datasheet - I can't make out what the current would be with Vaudio = H, Asel = L or H, VBUS=L (but with D+/R, D-/L OPEN).
In other words, does the current draw matter if Vaudio=H or L
or
is the current draw a function of the load on the outputs?
Good question, which you could answer by connecting a multimeter between the power source and the circuitry, to measure the current draw in the various states.
In general, the current draw of an amplifier is mostly determined by the power delivered to the load. The leftover bit is called the "quiescent current" in the data sheet.
He will also need a volt meter and an adjustable voltage source as the meter places a resistor in series with the load and actually measures the voltage drop across the resistor. The volt meter allows the OP to bring the voltage to what it should be and the adjustable voltage source will facilitate that adjustment.
I use a scope probe until the current gets low then a variation of what I described above. It gets very tricky when in the low uA range. And of course there is temperature to deal with. The easiest is to believe the data sheet as it is generally a guaranteed parameter.
If this is to be a USB powered application, no variable voltage source or series resistor current shunt is needed for tests. If this is to be a battery powered application, what is the operating voltage and how will you be regulating the voltage?
As I understand your question, the current draw of audio amplifier seems to be the primary concern, and it can be tested in isolation from the other components (except of course amplifier load and appropriate audio input).
@jremington I plan to use a RDA5807M chip to supply the audio L/R. The datasheet shows there is a builtin DAC and the output is supposed to be such that an external amp is not required but I may add one on the headphone side if needed.
This will be an esp32 application and It is battery-powered (I have a charging circuit, 3.3V voltage regulator, as well as fuel gauge IC already designed. I can include them if you want) and the intent is to use the USB C for charging, uploading sketches, as well as these headphones. I didn't want a separate usb-c controller because Tinyusb for espressif isn't well developed when it comes to usb audio and there are no decent libraries that I could find. So instead I'm gonna use the TS5USBA224 (or ONSEMI NCN1154 is kind of the same) to manage the usb and use analog audio as a work around.
I agree there are other things in my circuit that will need to be looked at, but I want to make sure the USB switch will work. Since I am new to this, I just want to make sure I am interpreting the datasheets correctly. On PDF pages 5 and 6 for the TS5USBA224 it shows this
I interpret the Leakage currents with power to the board i.e. Vaudio = 3.3V to be 50 nA for both the audio and usb channels with VD+/R =Open
So in english, I would say "if the chip is powered with +3.3V, but there is nothing plugged in, then I sould expect 50 nA current draw" If this statement is correct then I am done since that is nothing. I just wanted to make sure the switch wasn't sucking juice unless I actually powered it off i.e. set Vaudio = 0V.
Yeah, i noticed that after i sent my last post. 10uA is borderline. I may put a pchannel mosfet high side switch and turn it off when not in uae. Problem is im my application, space is a premium. Anyway, thanks for the help @jremington. Ill build a breakout of the radio portion of the circuit and let you know if it works.
