triple switcher
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From: John Larkin on 14 Nov 2009 13:40 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,P89092 And other ideas? John
From: MooseFET on 14 Nov 2009 16:40 On Nov 14, 10:40 am, 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 How about LT3507? LT3564 seems to get a lot of switcher into a small package. I haven't been able to find a way to do it with either a PIC or a 555 but I'll keep thinking about it.
From: dagmargoodboat on 14 Nov 2009 20:35 On Nov 14, 4:40 pm, MooseFET <kensm...(a)rahul.net> wrote: > On Nov 14, 10:40 am, 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 > > How about LT3507? > > LT3564 seems to get a lot of switcher into a small package. > > I haven't been able to find a way to do it with either a PIC or a 555 > but I'll keep thinking about it. Either's fine. (view in fixed font) U1 U2 ... U11 .-------. .-------. .-------. +12v >--|gnd Vdd|--|gnd Vdd|-...-|gnd Vdd|--> +5v '-------' '-------' '-------' U1-U11 = 555 or PIC. -- Cheers, James Arthur
From: MooseFET on 15 Nov 2009 12:20 On Nov 14, 5:35 pm, dagmargoodb...(a)yahoo.com wrote: > On Nov 14, 4:40 pm, MooseFET <kensm...(a)rahul.net> wrote: > > > > > On Nov 14, 10:40 am, 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 > > > How about LT3507? > > > LT3564 seems to get a lot of switcher into a small package. > > > I haven't been able to find a way to do it with either a PIC or a 555 > > but I'll keep thinking about it. > > Either's fine. > > (view in fixed font) > > U1 U2 ... U11 > .-------. .-------. .-------. > +12v >--|gnd Vdd|--|gnd Vdd|-...-|gnd Vdd|--> +5v > '-------' '-------' '-------' > > U1-U11 = 555 or PIC. That isn't 3 voltages per chip as the OP asked for. It also doesn't really regulate. I have made a booster regulator with the LM555 that worked just fine. I have figured out the design for a bucker that looks like it would work but so far without adding a lot of external parts I haven't come up with a way to regulate more than one voltage.
From: John Larkin on 15 Nov 2009 13:41
On Sat, 14 Nov 2009 13:40:27 -0800 (PST), MooseFET <kensmith(a)rahul.net> wrote: >On Nov 14, 10:40�am, 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 > >How about LT3507? Lots of external parts, schottkies and inductors. > >LT3564 seems to get a lot of switcher into a small package. We already stock the LTC3407, 3411, and 3412, all similar. But it would be great if somebody did a minimal-parts, minimal-size triple synchronous switcher, ideally with internal inductors. I *told* LTC to do this, and, incredibly, they haven't got around to it. It's not as if FPGAs are losing popularity. The Spartan 6 parts will run from two supplies (Vccint can run from 3.3) but we want to use a DDR dram, at 1.8 volts, so we're back up to three. > >I haven't been able to find a way to do it with either a PIC or a 555 >but I'll keep thinking about it. To keep the inductor and cap sizes down, you've got to switch at a MHz or two. John |