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dunv
Joined: 15 Apr 2005
Posts: 5
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 03 Aug 2005 14:40 Could linear regulator and swith regulator be integrated? |
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| Our team design a chip which integrated two linear regulators and one DC/DC converter which controled by 270kHz PWM signal.But now we find if turn on the DC/DC converter with loading(about 300mA),big noise will be find in the linear regulator output.And in the market we haven't find similar product. what's the reason of this?please help me,thanks.
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bamdad
Joined: 14 Nov 2001
Posts: 116
Helped: 5
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03 Aug 2005 14:49 Re: Could linear regulator and swith regulator be integrated |
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| I don't know of a single chip DC/DC converter with onchip linear regulator, but I there are several hybrid modules, which combine the two in a very small package, to name a few, you can check out MINMAX S200 series...
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VVV
Joined: 26 Nov 2004
Posts: 1584
Helped: 290
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04 Aug 2005 3:14 Re: Could linear regulator and swith regulator be integrated |
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Of course it is possible. Most switching regulators have a built-in reference, which is nothing but a linear regulator.
Anyway, here is one example from TI: http://focus.ti.com/docs/prod/folders/print/tps65140-q1.html
I recall Linear Technology made something similar, too.
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Btrend
Joined: 26 Dec 2003
Posts: 424
Helped: 55
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04 Aug 2005 3:24 Re: Could linear regulator and swith regulator be integrated |
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it's possilbe to do that, but u should pay attention to
1. noise from the ground/power bounce , multiple bonding is prefered
2. noise coupling in Vref, cause Vref are usually coming from the same source, it must be a low impedance output
3. careful layout , and enough separation of different block
4. pin assignment & pin arrangement
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fantaci
Joined: 28 Sep 2002
Posts: 59
Helped: 1
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04 Aug 2005 6:54 Could linear regulator and swith regulator be integrated? |
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| It is possible. Our chip uses several DCDC converters and several LDOs in one chip.
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dunv
Joined: 15 Apr 2005
Posts: 5
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04 Aug 2005 17:37 Could linear regulator and swith regulator be integrated? |
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| Thank you all very much. To VVV,I have read the specification of you linked, The noise of the output also be very big ,peak to peak voltage is about 200mV, do you know some IC chip could get a lower noise as 50mV(peak to peak)?
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VVV
Joined: 26 Nov 2004
Posts: 1584
Helped: 290
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05 Aug 2005 17:22 Re: Could linear regulator and swith regulator be integrated |
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Sorry, I cannot find the other device I knew about.
But where did the 200mV peak to peak come from? I did not see it in the datasheet.
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05 Aug 2005 17:22 Ads |
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dunv
Joined: 15 Apr 2005
Posts: 5
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05 Aug 2005 17:47 Could linear regulator and swith regulator be integrated? |
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| I am sorry, I made a mistake with the noise and the load influence,this chip's noise is about 50mV,it's very good, thank you very much,vvv.
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