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mitgrace
Joined: 08 May 2004
Posts: 335
Helped: 4
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 07 Jun 2004 16:42 How to design "current sense amp " in thr BUCK reg |
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Dear all:
Does any body know how to design ""current sense amp " in thr BUCK regulator , Now I use external Power MOS (PMOS and NMOS) . so that I don't how to detect the current ? and How to do the ramp compensation ?
Does anybody know that ? Any document ? Thanks
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andy2000a
Joined: 18 Jul 2001
Posts: 756
Helped: 7
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| 08 Jun 2004 8:55 Re: How to design "current sense amp " in thr BUCK |
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please reading
bipolar an dmos integrated circuit design
10.9 switch regulator page 532 fig-10.33 show SG1524/3524
use current sense limit for output BJT device ...
another ua78s40 use series 0.3 ohms for current sense
if you use mos you can series resistor ..
as I know someone use Power MOSFET internal Rds ..
becuase power mos "ON" have 20~30m Ohm * 5A = 150mV ..
you can sense current ...
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mitgrace
Joined: 08 May 2004
Posts: 335
Helped: 4
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| 08 Jun 2004 12:30 Re: How to design "current sense amp " in thr BUCK |
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Dear andy :
Thanks your comment , Actuall I use external PMOS and NMOS , so that I don't know where we can sense the current , Maybe lx , or Mos , But I don't have sense now , My specific is 3.3 to 1.8 Buck regulator , I am looging the PMOS/NMOS , Do you have any comment ? Thanks
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andy2000a
Joined: 18 Jul 2001
Posts: 756
Helped: 7
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| 05 Oct 2004 7:44 Re: How to design "current sense amp " in thr BUCK |
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as I know , someone use split mos finger .. and use current-mirror for measure current ..
but I think use small resistor is easy way
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