Forums

Powering a LPC2114 ARM7

Started by Bob January 5, 2004
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?
Bob wrote:
> 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?
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 (:
Bob wrote:

> 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?
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
> 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.
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.
> the battery? Is there a single device, such as a DC/DC converter > that can produce these voltages?
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.
In article <f3e22ae5.0401050838.7c40c34c@posting.google.com>, 
rob@slackware.com (Bob) wrote:

> 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? >
tps65010 David Collier email can be sent to Dexdyne.com , under name from_usenet@
"Lewin A.R.W. Edwards" wrote:
> > > 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. > > 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. > > > the battery? Is there a single device, such as a DC/DC converter > > that can produce these voltages? > > 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.
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 (cbfalconer@yahoo.com) (cbfalconer@worldnet.att.net) Available for consulting/temporary embedded and systems. <http://cbfalconer.home.att.net> USE worldnet address!
David Collier <from_usenet_comp_arch_embedded@dexdyne.com> wrote in message
news:memo.20040106115123.4084A@dexdyne.zen.co.uk...
> In article <f3e22ae5.0401050838.7c40c34c@posting.google.com>, > rob@slackware.com (Bob) wrote: > > > 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? > > > > tps65010 > > David Collier > > email can be sent to Dexdyne.com , under name from_usenet@
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
"Lewin A.R.W. Edwards" wrote:
> > > 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. > > 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. > > > the battery? Is there a single device, such as a DC/DC converter > > that can produce these voltages? > > 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.
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.
In article <btvk6f$77a19@imsp212.netvigator.com>, EZ@onearth.com says...
> > David Collier <from_usenet_comp_arch_embedded@dexdyne.com> wrote in message > news:memo.20040106115123.4084A@dexdyne.zen.co.uk... > > In article <f3e22ae5.0401050838.7c40c34c@posting.google.com>, > > rob@slackware.com (Bob) wrote: > > > > > 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? > > > > > > > tps65010 > > > > David Collier > > > > email can be sent to Dexdyne.com , under name from_usenet@ > > > 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
I might visit that site more than once if someone would remove the awuful sound effects! Mark Borgerson