Powering a LPC2114 ARM7

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I am designing a board using a Philips LPC2114 (nice chip).  It uses
1.8v for the core, 3.3v for I/O, and I also need 5v for some other
circuits on the board.  None of them use much current.  The power
supply is a 12v battery.

What is the best way to get these voltages, without running down
the battery?  Is there a single device, such as a DC/DC converter
that can produce these voltages?

Re: Powering a LPC2114 ARM7
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The key question here is whether you need switching
regulators or not.  If so, they will cost money and
board space.  If not, linear regulators will do at
a lower cost.

You have to work the tradeoffs between using a bigger
battery or a more expensive board.  You've not given
us enough information to tell.

Start by deciding what is the largest battery that
you could use.  From there, see if linear regulators
will do the job.  If so, go for it.  If not, run some
numbers on power consumption with a switcher on your
highest load and see what happens.  This is how
engineering works (:


Re: Powering a LPC2114 ARM7

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If you really don't need much power, linear regulators may do the job. Just add
up your current consumptions an look how far you can go with your battery's
power. Or you may use a mixed configuration, i.e. doing the 12V-to-5V step with
a switching regulator (e.g. LM2575) and using linear regulators to get 3.3 and
1.8V out of 5V (TI's TPS70151 5V->3.3/1.8V dual output regulator comes to mind)

HTH,
Jens


Re: Powering a LPC2114 ARM7
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This question has arisen in the Yahoo LPC2100 discussion group
recently. Most people recommended linear regulators. Certainly, all
the extant and proposed EVBs use them. But, most people are not
designing battery-powered appliances. You can certainly realize higher
efficiencies with alternative designs, though.

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Not exactly. You can construct a SMPS that will generate all the
required voltages, but the cost will be quite substantial. If this not
a high-volume consumer product you're designing, it is easier - much
easier - to use linear regs.

Re: Powering a LPC2114 ARM7
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At least it simplifies the power calculations.  The only value of
interest on each voltage line is the current.  Add them, and
multiply by 12, and you have total power usage and dissipation.  A
minor advantage is that you can possibly mount those serial
regulators in a favorable location for cooling.
--
Chuck F ( snipped-for-privacy@yahoo.com) ( snipped-for-privacy@worldnet.att.net)
   Available for consulting/temporary embedded and systems.
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Re: Powering a LPC2114 ARM7
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A lot of people think of inductor based regulators for efficient power
conversion.  But there are also switched capacitor regulators that do a
good job.  I am using the TPS60500 which can be programmed for its
output voltage and can be very efficient.  But it won't work with a 12
volt input.  A voltage halfing circuit in front of two of these should
do the job.  But after a look around, I don't see one that will take 12
volts input and provide more than 20 mA of current.  So maybe this is
not really practical.  Or maybe you can do a better job of looking for a
small, cheap charge pump to cut the 12 volts to 6 volts.  Then the
TPS60500 should be just what you want.

Re: Powering a LPC2114 ARM7

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tps65010

David Collier

email can be sent to Dexdyne.com , under name from_usenet@

Re: Powering a LPC2114 ARM7

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take a look at my board at http://arm.web7days.com

the DC-DC convertor for 3.3 V and 1.8 V are on board.

EZ arm




Re: Powering a LPC2114 ARM7
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I might visit that site more than once if someone would remove the
awuful sound effects!


Mark Borgerson

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