Hello Everyone!
Recently ive been working on some amplifier project and im using the TDA1558Q. Im very confused with this chip, First of all ive copied the exact stereo circuit with the one in the datasheet and im facing problems. While pin 14 is low (Mute) everything is normal about a 100mA draw, but when the pin 14 goes high (Vp) it draws 1.2A with no external input and it measures 2.2V dc at the inputs and 6+V dc output. I thought it might be a faulty chip so i used a new one it does the same thing. Anyone that knows what is going on and what am i doing wrong with this because im very confused.
Recently ive been working on some amplifier project and im using the TDA1558Q. Im very confused with this chip, First of all ive copied the exact stereo circuit with the one in the datasheet and im facing problems. While pin 14 is low (Mute) everything is normal about a 100mA draw, but when the pin 14 goes high (Vp) it draws 1.2A with no external input and it measures 2.2V dc at the inputs and 6+V dc output. I thought it might be a faulty chip so i used a new one it does the same thing. Anyone that knows what is going on and what am i doing wrong with this because im very confused.
So that is what im implementing with no changes. Its hooked to a linear power supply that i made. its very basic design as every linear power supply with an added regulator circuit with the lm317 connected to a base of a bjt power transistor. It does provide 14v stable with no noise ive tested it in more projects. Ive also tested with a commercial SMPS of 12V it does the same. I havent drawn any schematic but when i do i will attach it for more details about the curcuitt.
I firstly did solder it on these empty diy pcbs but i also tried it on a breadboard. I got the parts from a local store, ive bought many parts from it they are all legit. After all i have 3 tda's the 2 of them are used and the 1 is new they all behave the same. No input and no speaker connected i get the same 2.2V DC on both inputs and the DC on the outputs and about 1A draw.
Data sheet claims less than 100uA in standby, but you mention 100mA in standby. Did you intend u rather than m?
Data sheet is very lacking in detail. I would think input bias voltage would be about half of supply voltage, but data sheet gives no info.
Have you checked carefully for solder shorts? I would look for unexpected continuity between pins with ohmmeter.
Does your power supply have adjustable voltage? It might be insightful to see how bias voltages vary with changing supply voltage. What is voltage on pin 4 and how does it respond to variable supply voltage? Data sheet seems silent on these questions.
Same questions re pin 15.
Data sheet is very lacking in detail. I would think input bias voltage would be about half of supply voltage, but data sheet gives no info.
Have you checked carefully for solder shorts? I would look for unexpected continuity between pins with ohmmeter.
Does your power supply have adjustable voltage? It might be insightful to see how bias voltages vary with changing supply voltage. What is voltage on pin 4 and how does it respond to variable supply voltage? Data sheet seems silent on these questions.
Same questions re pin 15.
I just tested it in the breadboard with no input or output connected this is what i got. Ive built this many times everything is connected as it should no joined spots or anything. The supply its fixed voltage but i can change some resistors to a potentiometer and make it adjastable. Thats what i though, datasheed seems weird and i wasnt sure if i was missing something or not ive read it 100 times. In standby yes i did get mA not uA.
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It's a chip intended for car use, so 6 V (about half supply) on all outputs is normal. Also 2,2 V DC on inputs seems normal, that allows ac input swing - that's why the data sheet specifies input caps.
Did you connect caps at the inputs and speakers via the btl outputs (not to ground!)?
I have similar original philips tda 1553 chips that behave very well.
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Thanks for pointing it out!
If I remember correctly with my 1553 chips I had some strange current draw if signal ground and power ground were connected directly. Could you try separating them with a capacitor (maybe 1-10 uF)?
Or just leave signal ground open for testing?
I did try to separate the input ground but then it draw 4A like crazy I don't know it seems to be like that. I guess I have to find some other amp for my project because i want to run 2 at the same time and 2A draw with both oscillating isn't ideal. I just powered it again multiple times and it draw from 800mA to 1.1A without changing anything in the circuit, I've never seen anything like that.