Charlize Low V Supply

[serengetiplains]

Has anyone experience adding an outboard 5V supply to the Tripath TA2020? I searched several strings but came up empty handed.

The data sheet shows the 5V generator is pin 30. It supplies pins 2 and 8. I would suppose one could just snip pin 30, and add the supply of choice to power up on start up? Will I have a problem with power supply turn on sequence? Any other thoughts or advice?

[Sjef]

Yes it can be done, in fact it has been done allready. Have a look at the Ref-T design, this one use a seperate 5V regulator to power the input circuit of the Tripath chip. You can even put in two regulators, one for the 5V digital supply and one for the 5V analog supply. Since there doesn't flow any high currents at these point I would go for shunt regulators. Stay away from the 3pin series regulators, the onchip supply is most probably better then them. Just make sure the RC constant of all the power supllies is about the same and there should be no problem with latch-up

[BWRX]

Originally posted by serengetiplains
Has anyone experience adding an outboard 5V supply to the Tripath TA2020?

Originally posted by Sjef
Yes it can be done, in fact it has been done allready. Have a look at the Ref-T design

Sjef is correct, I looked at the use of separate supplies during the design of the Ref-T which is based on the TA2021B. I originally used separate regulators for each of the 5 power pins. Do not do this unless you enjoy replacing chips. Make sure that the VDDA, VDD1, and VDD2 pins are connected to the same supply. I ended up using a 3 terminal regulator set to output 14V and ran separate traces for each pin. You do not have to use the internal 5V regulator but make sure the V5D and V5A pins are connected to the same supply. Use local decoupling right next to each pin. You may also use additional supply filtering if desired. I did not use any and the results were still excellent. I did use the chip's internal 5V regulator to supply power to a couple LEDs to signal when the chip was on and if there was a fault.

Make sure the 5V supply comes up before the 12V supply to avoid a horrid turn on thump. I ended up connecting the input of the 5V regulator to the same raw supply for the 14V regulator and used a 555 timer to unmute the amp about 1 second after the raw supply was turned on. This worked very nicely.