triple switcher
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From: John Larkin on 20 Nov 2009 23:18 On Thu, 19 Nov 2009 15:18:08 -0800 (PST), "langwadt(a)fonz.dk" <langwadt(a)fonz.dk> wrote: >On 18 Nov., 22:18, John Larkin ><jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >> On Sat, 14 Nov 2009 10:40:44 -0800, John Larkin >> >> >> >> <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >> >> >We keep running into the requirement to turn +12 or +5 volts into 3.3, >> >1.2 (fpga core), and usually a third voltage, 1.8 (for drams) or 2.5 >> >(fpga Vccint). We'd like to consolidate this to save board area and >> >general complexity. Any suggestions? >> >> >LTM4615 looks interesting, a bit expensive but very small. >> >> >http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1424,P8... >> >> >And other ideas? >> >> >John >> >> Well, the resolution was to use two LTM8023's, which we have in this >> case, to make 3.3 and 1.2 from available +5, and an LM1117 to make 1.8 >> from 3.3. Clumsy. Somebody should make a tiny triple switcher module >> to run FPGAs; they'd sell a lot of them. >> >> John > >how much current do you need? > >seen the ADP2121? >http://www.analog.com/static/imported-files/data_sheets/ADP2121.pdf >has an example layout, 2.5x3.4mm one layer for 600mA 1.8V >though it looks like it only available with 1.8V out > >the adp2109 looks similar but is available with 1.0,1.2,1.5,1.8V >output > >-Lasse We use LTC3411's a lot, tiny little MSOP-10 synchronous switchers. They are rated for 1.6 amps and are happy doing that. But they only work up to 5.5 volts in, so we use the LTM thing to get down from +12 to +3.3 and then let the tiny switchers take over for the lower stuff. John |