[SI-LIST] Re: Xilinx SpartanT-3/3E/3L FPGA Power Solutions-- FromMonolithic Solutions
- From: "Vivekkumar M-TLS,Chennai" <Vivekkumarm@xxxxxx>
- To: <Istvan.Novak@xxxxxxx>
- Date: Wed, 4 Mar 2009 18:10:38 +0530
Dear Istvan Novak,
Thank you for your inputs.
If we design the Regulator for an entire range, will there be an effect
on the efficiency?? Please advice us.
Regards
Vivek
-----Original Message-----
From: Istvan.Novak@xxxxxxx [mailto:Istvan.Novak@xxxxxxx]
Sent: Wednesday, March 04, 2009 5:44 PM
To: Vivekkumar M-TLS,Chennai
Cc: si-list@xxxxxxxxxxxxx
Subject: Re: [SI-LIST] Xilinx SpartanT-3/3E/3L FPGA Power Solutions--
FromMonolithic Solutions
Dear Vivek,
You can approach the question from the opposite end as well. If you have
a given design for a certain maximum current, you rightfully want to use
that design with a load current anywhere between zero and full maximum
allowed load. And of course, you dont want to change components on the
fly just because the load current has changed. Your point is valid
though:
external components should be
designed with the operational range in mind. If you design the circuit
to work well in the entire range (in this case 0 to 3A) but use it only
in a subrange (0 to 1A), the result will be somewhat suboptimum, but
still may work very well.
Regards,
Istvan Novak
SUN Microsystems
Vivekkumar M-TLS,Chennai wrote:
> Dear All ,
>
> I happened to look into the Step Down Converters from MonothilicPower.
> The following is the statement made in the webpage:
>
> MPS presents the MP2309 and MP2307 23V synchronous step-down
regulators.
> With an output current rating of 1A and 3A respectively, the MP2309
> and
> MP2307 are pin compatible with the 2A MP2305, forming a power
> management solution that can easily scale from 1A to 3A without
> circuit board re-design.
>
> http://www.monolithicpower.com/fpga_xilinx_spartan.htm
>
> Could anyone please explain how come this is feasible.
>
> Following are the general rules for a step Down converter:
>
> 1) Since the input capacitor (C1) absorbs the input switching current
> it requires an adequate ripple current rating.
> 2) The worst-case condition occurs at VIN = 2VOUT,where IC1 = ILOAD/2.
> 3) Inductor should be chosen that it will not saturate under the
> maximum inductor peak current. The peak inductor current hence is
> dependent on the Load Current.
>
> Hence how is that if we want to change to a different load
> requirement, only a Monolithic power solution Chip change is enough.
> How come the external components remain with the same rating for
> different loads.
>
> Please can anyone explain this . It will be of great learning to us
> here.
>
> Thanks
> Regards
> Vivek.
>
>
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