Hello everyone,
I ordered chip and made circuit like was suggested in datasheet.
Everything works but there is no +12V on pin25 HSD.
One of my friend said, that this could be counterfeit chip. Can it be, or just leave it as is?
www.st.com/resource/en/datasheet/tda7560.pdf
I ordered chip and made circuit like was suggested in datasheet.
Everything works but there is no +12V on pin25 HSD.
One of my friend said, that this could be counterfeit chip. Can it be, or just leave it as is?
www.st.com/resource/en/datasheet/tda7560.pdf
Pin 25 looks to be a dangerous input offset detector. There is probably an application note somewhere that explains it but it is reasonable to assume if the offset in your circuit is OK there is no flag from this pin. Personally I think this counterfeit chip thing has become a sort of witch hunt.
It can be used as offset detector, mainly Pioneer headunits uses it as high side driver, to drive remote output.
Moderator - can You please move thread, i posted in wrong section. This is correct http://www.diyaudio.com/forums/chip-amps/
Thank You sorry, new user.
Thank You sorry, new user.
Moved as requested.
You should post a schematic of how you have implemented your amplifier.
Do you have the required 10K pull down resistor on pin 25? Also standby and mute have to be asserted in a specific way to enable the offset detection.
Seems like Vstby and mute need to be at specific voltages for this to work.
Do you have the required 10K pull down resistor on pin 25? Also standby and mute have to be asserted in a specific way to enable the offset detection.
Seems like Vstby and mute need to be at specific voltages for this to work.
Schematic is the same like in datasheet.
Actually I dont need offset detection, so there is no pull down, I am just worried as there is no voltage on HSD pin.
Actually I dont need offset detection, so there is no pull down, I am just worried as there is no voltage on HSD pin.
What makes you think there should be a voltage on pin 25?
I would connect the chip exactly like the data sheet describes for the measurement of the voltage on pin 25. Then measure.
I agree with Scott that counterfeit chips has become a bit of a scapegoat. Every time a circuit doesn't work, that's the go-to reason. Some seem to forget to double-check the circuit.
Tom
I would connect the chip exactly like the data sheet describes for the measurement of the voltage on pin 25. Then measure.
I agree with Scott that counterfeit chips has become a bit of a scapegoat. Every time a circuit doesn't work, that's the go-to reason. Some seem to forget to double-check the circuit.
Tom
Also the datasheet should be read carefully.
I had oscillation on the output of a TDA7294.
I blamed the chip and layout.
Turned out I had low gain in my design and the datasheet says there is a minimum gain for stability.
I managed to tame the chip with a capacitor across inverting and none inverting inputs.
With respect to counterfeit chips first at least see if there is a cheap pin for pin part from another manufacturer, beyond re-branding and/or upgrading the chance of a fake falls off rapidly. Of course there are the simple total fakes where only the package is the same and there is no functionality at all.
So op-amps and transistors are probably most common. We had a set of masks stolen on a generic CMOS system on a chip but in that case there was government intervention. There also were DAC's upgraded to mil spec and sold to the Navy, NCIS sent a SWAT team to break up the operation.
So op-amps and transistors are probably most common. We had a set of masks stolen on a generic CMOS system on a chip but in that case there was government intervention. There also were DAC's upgraded to mil spec and sold to the Navy, NCIS sent a SWAT team to break up the operation.
Yes that is also possible as well as stolen test rejects that were supposed to be destroyed.
- Status
- Not open for further replies.