To Whom It May Concern:
My name is Richard Carter. I am in a senior design group at Bucknell University. We have been trying to design your class-T digital amplifier utilizing the TA3020 technology. We have ordered 10 of your TA3020 chips from the British retailer Profusion PLC.
Unfortunately, we are down to our last TA3020 chip, and I am emailing hoping you can offer any suggestions as to what might be causing our problems. I will try to lay out our design and specs… then what I believe to be causing the chips to blow. My whole group will much appreciate any advice you can give us.
Vpp=58v
Vnn=-58v
Vn10=-48v
V5=5 volts
Those are our main supply voltages. We built our own power supply. We built the chip and its input and control circuitry on a protoboard (non soldering). The output stage was built on a spring board so that it could handle higher current. We took careful consideration to order the recommended parts for the circuitry that your data sheets specify (ta3020 sheet, and the ta3020eb). Same for the output (mur 120 diodes, etc.)
We seem to have 2 main problems. One is that we lose our 10 volt regulator at vn10 and the vn10 voltage goes up to vnn. We lost a few chips when this happens… What causes the chip to blow if vn10=vnn? We seemed to have fixed this problem by designing a circuit to limit current over the regulator using a pnp bjt, and that seems to protect vn10. Also at pin 1 on the TA3020 the evaluation board data sheet calls for a 47uf and .1uf cap to go between pin 1(vn10) and vnn. When we tried to do this we found that it clamps pin 1 at vnn. This then caused our chip to fail.
The second problem is the output section in general. Without the output section hooked up to the chip we can get pwm signals out of the chip, as well as ramp functions. Pin 48 and 2 give us the pwm. Pin 45 and 5 give us the ramp signal. Once the output is hooked up the chip normally mutes. I emphasize that to the best of our knowledge everything is connected properly according to your datasheets using the correct parts. We then reduced the current sensing resistors at pins 31, and 33 as specified by the data sheet so that current sensing was not so sensitive. When we put in 2 2.2kohm resistors, the chip unmuted. We had a continuous high switching sound form the mosfets (we assumed they were switching). When we took the signal at the output (8 ohm load) we got a ripple sin wave (6vpp) clamped at +46 volts. This was independent of the input signal. This worked for about 10 minutes, and then the fuse on our power supply blew. When we checked everything, the chip had blown, and channel 1’s mosfets both were shot.
Our pcb board has arrived (designed off of your eval board using express pcb software). We have one chip left and can’t afford to lose it as well. We are hoping you could offer us suggestions as to what might be going wrong so that we can fix it, or protect the chip so we don’t lose it. We are thinking of dropping our voltages down to +-30 or +-20 if we can find a transformer that will do it.
My final question is about your data sheets. There seems to be some discrepancies between the TA3020 chip board and the eval board. We are confused as to which one is correct, or why there are differences?
Any help you can give will be truly appreciated. I already want to thank you in advance. Take care and I hope to hear from you soon so that we have some idea where we need to head tomorrow to try to get our TA3020 amp working. If you need schematics of our designed stages I can send them to you. Thanks.
My name is Richard Carter. I am in a senior design group at Bucknell University. We have been trying to design your class-T digital amplifier utilizing the TA3020 technology. We have ordered 10 of your TA3020 chips from the British retailer Profusion PLC.
Unfortunately, we are down to our last TA3020 chip, and I am emailing hoping you can offer any suggestions as to what might be causing our problems. I will try to lay out our design and specs… then what I believe to be causing the chips to blow. My whole group will much appreciate any advice you can give us.
Vpp=58v
Vnn=-58v
Vn10=-48v
V5=5 volts
Those are our main supply voltages. We built our own power supply. We built the chip and its input and control circuitry on a protoboard (non soldering). The output stage was built on a spring board so that it could handle higher current. We took careful consideration to order the recommended parts for the circuitry that your data sheets specify (ta3020 sheet, and the ta3020eb). Same for the output (mur 120 diodes, etc.)
We seem to have 2 main problems. One is that we lose our 10 volt regulator at vn10 and the vn10 voltage goes up to vnn. We lost a few chips when this happens… What causes the chip to blow if vn10=vnn? We seemed to have fixed this problem by designing a circuit to limit current over the regulator using a pnp bjt, and that seems to protect vn10. Also at pin 1 on the TA3020 the evaluation board data sheet calls for a 47uf and .1uf cap to go between pin 1(vn10) and vnn. When we tried to do this we found that it clamps pin 1 at vnn. This then caused our chip to fail.
The second problem is the output section in general. Without the output section hooked up to the chip we can get pwm signals out of the chip, as well as ramp functions. Pin 48 and 2 give us the pwm. Pin 45 and 5 give us the ramp signal. Once the output is hooked up the chip normally mutes. I emphasize that to the best of our knowledge everything is connected properly according to your datasheets using the correct parts. We then reduced the current sensing resistors at pins 31, and 33 as specified by the data sheet so that current sensing was not so sensitive. When we put in 2 2.2kohm resistors, the chip unmuted. We had a continuous high switching sound form the mosfets (we assumed they were switching). When we took the signal at the output (8 ohm load) we got a ripple sin wave (6vpp) clamped at +46 volts. This was independent of the input signal. This worked for about 10 minutes, and then the fuse on our power supply blew. When we checked everything, the chip had blown, and channel 1’s mosfets both were shot.
Our pcb board has arrived (designed off of your eval board using express pcb software). We have one chip left and can’t afford to lose it as well. We are hoping you could offer us suggestions as to what might be going wrong so that we can fix it, or protect the chip so we don’t lose it. We are thinking of dropping our voltages down to +-30 or +-20 if we can find a transformer that will do it.
My final question is about your data sheets. There seems to be some discrepancies between the TA3020 chip board and the eval board. We are confused as to which one is correct, or why there are differences?
Any help you can give will be truly appreciated. I already want to thank you in advance. Take care and I hope to hear from you soon so that we have some idea where we need to head tomorrow to try to get our TA3020 amp working. If you need schematics of our designed stages I can send them to you. Thanks.
Hi,
I built up a Amp with a
TA3020 chip based on a PCB of Kay (see http://www.diyaudio.com/forums/showthread.php?s=&threadid=3906).
My TA3020 chips came from Profusion PLC too. Fortunately (for me
) I hadn't such problems as you have found. So I can give you only general recommendations and hints:
1) I am rather sure, that the TA3020 needs a switch-on-sequence to work properly. First switch on the 5V and Vn10 and then (a second later or so) the Vpp and Vnn.
2) Due to 1) it is a good idea to use separate power supply units for 5V, Vn10 and for the main supply voltages. In our design there is a local voltage regulator for the 5V on the PCB. This voltage regulator and the Vn10 are fed by two small switching power supplies and the main supply voltages come from a conventional power supply with a big toroid transformer. So the voltages can be switched on/off independently.
3) For the very first testing I connect only the 5V and Vn10. The error LED is always attached. In the next test phase I connect the main supply voltages, but without a load at the output. The amp operates without a load too. When all seems to be OK, I connect the load for final tests.
4) Do not modify the current sensing resistors; if the chip does not start up and the error LED is switched on, then --- according to my experience --- this is a strong indication that something is wrong with the supply voltages or the output stage. In this case you must find the error first. This may be very frustrating, because there are many potential error causes which prevent the chip to start up and depending on the circumstances you can only guess. A storage oscilloscope may help to trace the very first switching activities of the output stage, when the amp is switched on.
5) Critical parts are the output transistors; take only one of the recommended types. The 330µF capacitors at the main supply voltage should be carefully selected too. Low ESR types are needed, normal type are getting hot.
6) Possibly the protoboard may cause the problems. I would take a PCB board in any case.
7) Check that the BBM timing control is set to slow values (120ns or 80ns).
Good Luck!
Bernhard
I built up a Amp with a
TA3020 chip based on a PCB of Kay (see http://www.diyaudio.com/forums/showthread.php?s=&threadid=3906).
My TA3020 chips came from Profusion PLC too. Fortunately (for me
) I hadn't such problems as you have found. So I can give you only general recommendations and hints:1) I am rather sure, that the TA3020 needs a switch-on-sequence to work properly. First switch on the 5V and Vn10 and then (a second later or so) the Vpp and Vnn.
2) Due to 1) it is a good idea to use separate power supply units for 5V, Vn10 and for the main supply voltages. In our design there is a local voltage regulator for the 5V on the PCB. This voltage regulator and the Vn10 are fed by two small switching power supplies and the main supply voltages come from a conventional power supply with a big toroid transformer. So the voltages can be switched on/off independently.
3) For the very first testing I connect only the 5V and Vn10. The error LED is always attached. In the next test phase I connect the main supply voltages, but without a load at the output. The amp operates without a load too. When all seems to be OK, I connect the load for final tests.
4) Do not modify the current sensing resistors; if the chip does not start up and the error LED is switched on, then --- according to my experience --- this is a strong indication that something is wrong with the supply voltages or the output stage. In this case you must find the error first. This may be very frustrating, because there are many potential error causes which prevent the chip to start up and depending on the circumstances you can only guess. A storage oscilloscope may help to trace the very first switching activities of the output stage, when the amp is switched on.
5) Critical parts are the output transistors; take only one of the recommended types. The 330µF capacitors at the main supply voltage should be carefully selected too. Low ESR types are needed, normal type are getting hot.
6) Possibly the protoboard may cause the problems. I would take a PCB board in any case.
7) Check that the BBM timing control is set to slow values (120ns or 80ns).
Good Luck!
Bernhard
Hy Richard,
I believe is the best to answer your questions here.
First at all, I don't try my layout at now, so Bernhard
do it.
1. I AGREE with all what Bernhard write!!
2. Maybe I can add some theoretical impressions.
3.
>Vpp=58v
>Vnn=-58v
>Vn10=-48v
>V5=5 volts
NEVER !!
If you start, it's better to finish a working 30W Amplifier.
Later you can try 1000W
4.
>Those are our main supply voltages. We built our own power
>supply. We built the chip and its input and control
>circuitry on a protoboard (non soldering). The output stage
>was built on a spring board so that it could handle higher
>current. We took careful consideration to order the
>recommended parts for the circuitry that your data sheets
>specify (ta3020 sheet, and the ta3020eb). Same for the
>output (mur 120 diodes, etc.)
Don't use a prototypboard.
You deal with high frequencies at high currents.
Use the original or my layout.
If you like to make your own layout, please,
don't change anything, what you can do in a same manner
like the original.
With my layout I do ONLY some small modifications!!
(sample: I don't make the 10V-supply on board, because
I had to make the power part in another way then the orginal.
If I can't predict the results, so I don't change)
5.
>We seem to have 2 main problems. One is that we lose our
>10 volt regulator at vn10 and the vn10 voltage goes up to
>vnn. We lost a few chips when this happens… What causes
>the chip to blow if vn10=vnn? We seemed to have fixed this
>problem by designing a circuit to limit current over the
>regulator using a pnp bjt, and that seems to protect vn10.
>Also at pin 1 on the TA3020 the evaluation board data sheet
>calls for a 47uf and .1uf cap to go between pin 1(vn10) and
>vnn. When we tried to do this we found that it clamps pin 1
>at vnn. This then caused our chip to fail.
I can't understand, what happens.
6.
>The second problem is the output section in general. Without
>the output section hooked up to the chip we can get pwm
>signals out of the chip, as well as ramp functions. Pin 48
>and 2 give us the pwm. Pin 45 and 5 give us the ramp signal.
>Once the output is hooked up the chip normally mutes. I
>emphasize that to the best of our knowledge everything is
>connected properly according to your datasheets using the
>correct parts. We then reduced the current sensing resistors
>at pins 31, and 33 as specified by the data sheet so that
>current sensing was not so sensitive. When we put in 2
>2.2kohm resistors, the chip unmuted. We had a continuous high
>switching sound form the mosfets (we assumed they were
>switching). When we took the signal at the output (8 ohm load)
>we got a ripple sin wave (6vpp) clamped at +46 volts. This was
>independent of the input signal. This worked for about 10
>minutes, and then the fuse on our power supply blew. When we
>checked everything, the chip had blown, and channel 1’s
>mosfets both were shot.
NEVER !!
change the current limiting.
7.
>Our pcb board has arrived (designed off of your eval board
>using express pcb software). We have one chip left and can’t
>afford to lose it as well. We are hoping you could offer us
>suggestions as to what might be going wrong so that we can
>fix it, or protect the chip so we don’t lose it. We are
>thinking of dropping our voltages down to +-30 or +-20 if
>we can find a transformer that will do it.
If you destroy 9 chips, you must have to order new ones.
So what can I say?
8.
>my final question is about your data sheets. There seems to
>be some discrepancies between the TA3020 chip board and the
>eval board. We are confused as to which one is correct, or
>why there are differences?
I can't see any discrepancies.
Don't forget,
you must change some resistors for the under-/ over-voltage
protection depence of your supply.
9. Additional
- check out the documentation from TriPath to use the
correct HEXFETs
- It's really a good idea to use a separate supply for 10V and 5V.
(don't forget the power sequence)
In this case it's must be possible to use a regulated supply
with current limiting for the power stage.
Thinking about this!
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
- I say it once more.
The TriPath is not a playing thing like a "normal" amplifier.
So, start with the lowest voltage as possible.
(don't forget to suit the resistors)
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Good Luck!
I believe is the best to answer your questions here.
First at all, I don't try my layout at now, so Bernhard
do it.
1. I AGREE with all what Bernhard write!!
2. Maybe I can add some theoretical impressions.
3.
>Vpp=58v
>Vnn=-58v
>Vn10=-48v
>V5=5 volts
NEVER !!
If you start, it's better to finish a working 30W Amplifier.
Later you can try 1000W
4.
>Those are our main supply voltages. We built our own power
>supply. We built the chip and its input and control
>circuitry on a protoboard (non soldering). The output stage
>was built on a spring board so that it could handle higher
>current. We took careful consideration to order the
>recommended parts for the circuitry that your data sheets
>specify (ta3020 sheet, and the ta3020eb). Same for the
>output (mur 120 diodes, etc.)
Don't use a prototypboard.
You deal with high frequencies at high currents.
Use the original or my layout.
If you like to make your own layout, please,
don't change anything, what you can do in a same manner
like the original.
With my layout I do ONLY some small modifications!!
(sample: I don't make the 10V-supply on board, because
I had to make the power part in another way then the orginal.
If I can't predict the results, so I don't change)
5.
>We seem to have 2 main problems. One is that we lose our
>10 volt regulator at vn10 and the vn10 voltage goes up to
>vnn. We lost a few chips when this happens… What causes
>the chip to blow if vn10=vnn? We seemed to have fixed this
>problem by designing a circuit to limit current over the
>regulator using a pnp bjt, and that seems to protect vn10.
>Also at pin 1 on the TA3020 the evaluation board data sheet
>calls for a 47uf and .1uf cap to go between pin 1(vn10) and
>vnn. When we tried to do this we found that it clamps pin 1
>at vnn. This then caused our chip to fail.
I can't understand, what happens.
6.
>The second problem is the output section in general. Without
>the output section hooked up to the chip we can get pwm
>signals out of the chip, as well as ramp functions. Pin 48
>and 2 give us the pwm. Pin 45 and 5 give us the ramp signal.
>Once the output is hooked up the chip normally mutes. I
>emphasize that to the best of our knowledge everything is
>connected properly according to your datasheets using the
>correct parts. We then reduced the current sensing resistors
>at pins 31, and 33 as specified by the data sheet so that
>current sensing was not so sensitive. When we put in 2
>2.2kohm resistors, the chip unmuted. We had a continuous high
>switching sound form the mosfets (we assumed they were
>switching). When we took the signal at the output (8 ohm load)
>we got a ripple sin wave (6vpp) clamped at +46 volts. This was
>independent of the input signal. This worked for about 10
>minutes, and then the fuse on our power supply blew. When we
>checked everything, the chip had blown, and channel 1’s
>mosfets both were shot.
NEVER !!
change the current limiting.
7.
>Our pcb board has arrived (designed off of your eval board
>using express pcb software). We have one chip left and can’t
>afford to lose it as well. We are hoping you could offer us
>suggestions as to what might be going wrong so that we can
>fix it, or protect the chip so we don’t lose it. We are
>thinking of dropping our voltages down to +-30 or +-20 if
>we can find a transformer that will do it.
If you destroy 9 chips, you must have to order new ones.
So what can I say?
8.
>my final question is about your data sheets. There seems to
>be some discrepancies between the TA3020 chip board and the
>eval board. We are confused as to which one is correct, or
>why there are differences?
I can't see any discrepancies.
Don't forget,
you must change some resistors for the under-/ over-voltage
protection depence of your supply.
9. Additional
- check out the documentation from TriPath to use the
correct HEXFETs
- It's really a good idea to use a separate supply for 10V and 5V.
(don't forget the power sequence)
In this case it's must be possible to use a regulated supply
with current limiting for the power stage.
Thinking about this!
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
- I say it once more.
The TriPath is not a playing thing like a "normal" amplifier.
So, start with the lowest voltage as possible.
(don't forget to suit the resistors)
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Good Luck!
I did my senior project using at TA3020 also, well it started that way. I decided however since i wasnt actually designing the class T architecture, and was just going to copy the app note i decided to get teh eval board from tripath. Like you my VN10 failed and the board blew up. At this point i decided to switch to the TK2350 eval board. This amp has pretty much the same characteristcs as the the TA3020. It also has the VN10 created onboard. Might i suggest checking out the tk2350 eval board's schematic to see how they created VN10. I have no no problems since the switch.
I know im not much help but i know what your going through :-(
Kurt
I know im not much help but i know what your going through :-(
Kurt
Hi!
I need some info: how should Mute input behave? I found in a not working IC that it is not a simple input with pull-up resistor, but it is similar to a TTL output (!). With pull-down resistor of 1k the voltage is 2.4V, with 220 ohm it's 1V, and short-circuit current is more then 20 mA. Can it be normal in any cases? V5=4.8V only.
I need some info: how should Mute input behave? I found in a not working IC that it is not a simple input with pull-up resistor, but it is similar to a TTL output (!). With pull-down resistor of 1k the voltage is 2.4V, with 220 ohm it's 1V, and short-circuit current is more then 20 mA. Can it be normal in any cases? V5=4.8V only.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.