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Class D Switching Power Amplifiers and Power D/A conversion

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Old 6th November 2013, 01:30 AM   #3731
opor is offline opor  Thailand
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Quote:
Originally Posted by lorylaci View Post
These are self-oscillating amps, operating at a variable frequency, depending on duty cycle, load, and of course component values etc.
When these amps are wired together inproperly, the differency of the switching frequencies appear due to interferrence. This problem applies for all swithcing amps. With fixed frequency ones, it is possible to synchronize the channels, or take their swithcing freq at least 20kHz apart, to decrease interferrence. However it is impossible with self-oscillating amps.
Care must be taken with wiring. Supply lines carry currents of both audio frequency and HF component. Wiring (and layout ) should be optimized to decrease this sensitivity.
Thank you very much ,Lorylaci. I have fixed my amp already. You said the truth about wiring problem .Now I am using aluminium foil shield cable as input signal cable. So all noise had gone. Sound great !!. I personally love this amp because it is stable , no latching when power on , no heating and especially I never found any damage with IR2110 even I make many mistakes such as mix up wiring , short speaker cable to ground etc. I can say that it is more stable than any amps I had done.And give more flatter FR response.Thank you.
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Old 7th November 2013, 08:59 PM   #3732
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Hi guys, I need help..

I made IRS900d amplifier and its not working..

Power Supplay is +-40V (after 2x120R 5W, supplay is 38.9V, resistors are cold and voltage drop is 0.9-1V)

When input is open,nothing can hear in speaker while you touch the input, then i hear sonic and hum, when you touching the input, it has normal sound in speaker but very distort
When input is in PC sound card, nothing can hear in speaker and when you play the music only can hear bits of bass very distort, it hears something like when you turn off the amp,distort music while main capacitors discharging, like amp dont have current...

I have 0.05V DC offset, everything is dead-cold
Bias 12.39V ref to ucc-
-5.4V and 5.4V for TL071 on pins 4 and 7

Level shifer is HEF4049BP by NXP (maybe its wrong IC, i don know)

Colector of 2N5401 has 4.7V ref to gnd
Hin of 2110 has -27.3V ref to gnd and 12.3V ref to ucc-
Lin of 2110 has -38.2V ref to gnd
Gate of negative mosfet has -37V
Gate of positive mosfet has 0V

IR2110 is good, work on another amp

Without 4049 IC
Colector of 2N5401 is -38.2V
Hin has -35V ref to gnd and 0.6V ref to ucc-
Lin has -8.2V ref to gnd and 0.6V ref to ucc-

Without 2110
Output has -38V

Output transistors IRF540N with 22R gate resistor
Output Filter 30uH+470n ; 22uH+470n ; 30uH+1uF ; 22uH+1uF ; 16uH+470n ; 16uH+1uF (always the same)

On output I don have 1.5K 5W to gnd and zobel network, this is only for testing..

What can I do? Can anyone help me?

This is schematic that I use
http://zaslike.com/files/ssbqo7d0huq50swfxx7.png

Last edited by Dzony988; 7th November 2013 at 09:09 PM.
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Old 8th November 2013, 08:45 AM   #3733
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Default IRS900

Hi Dzony988 please check the attachment,it may help.
Attached Images
File Type: jpg r-osc10 info IRS900 by NMOS.jpg (196.7 KB, 1372 views)
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Old 8th November 2013, 10:20 AM   #3734
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Hi don

It is the same schematic like mine, only that I use only two CD4049 inputs, like on original board
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Old 9th December 2013, 04:20 AM   #3735
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Default ucd

Hello
greetings some mods to the old schematic
warm regards
andrew lebon
Attached Images
File Type: jpg Kve1eiE.jpg (600.2 KB, 1063 views)
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Old 13th December 2013, 07:13 PM   #3736
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High to all.. I have one question

Why main version of UCD amp (post 1 started by andrewlebon ) dont work stabile with high voltages (+-70V and higher)..

I always had problem with level shift transitors 2N5401, always explode one of them just after powering up, rest of them are also dead, IR2110 too.

I tryed with mpsa92 but its the same problem... Sometimes transistors expolde after 10 days of working amp, and you just power up amp and bum, they explode and kill IR2110..

I use IRFP250, 250N, IRFB4227, 4229, IRFP240...... everuthing waqs stabile on lower voltages..

I think its a problem with 120R resistor and 2.2K resistor on that part.. Maybe other vaules make it stabile.. What do you think?
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Old 14th December 2013, 11:17 PM   #3737
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Amplificador HighEnd Clase D de 25W a 1250Wrms sólo con 2 MosFets N
Hi Dzony
greetings link to this amp
warm regards
andrew lebon
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Old 15th December 2013, 04:35 PM   #3738
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Yes, I know but this amp is unstable on high voltages!

Good working on +-60 65V after that level shift transitors explode... 2N5401, MPSA92 all the same, they sometimes expolde on start up and kill IR2110
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Old 15th December 2013, 05:03 PM   #3739
pergo is offline pergo  Italy
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try MPSW92 or MJE350
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Old 17th December 2013, 07:23 AM   #3740
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Quote:
Originally Posted by Dzony988 View Post
Yes, I know but this amp is unstable on high voltages!

Good working on +-60 65V after that level shift transitors explode... 2N5401, MPSA92 all the same, they sometimes expolde on start up and kill IR2110
The level shifter has a current generator at the top. Check the values, also you can adjust the generated current with the 120 ohm resistor (0,6V drop).
Default is about 5mA with the 120 Ohm.
Dissipation is about 5mA*half supply voltage per transistor. (current generator transitor has double the averegae dissipation than the differential pair). Check transistor datasheet for dissipation.
Be sure to use really fast transistors!

If you adjust the current change also tail resistors. With 5mA and 2.2kOhm the drop is 11V. Be sure to check it is over IR2110 logic high for IR2110 supply voltage.
Also this gives some dead-time setting possibility
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