Post by thread:[EE] Switch Mode Current regulation

Hi As part of a battery charging circuit I need to regulate the current. The problem is I cannot lose the heat in the hand held device so need to use a Switch mode Current regulator. I have found them to be very thin on the ground. Can anybody recommend one? It needs to be capable of about 1500ma at 5V (I am charging 4 AA NIMH batteries) Many thanks Tim -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email spam_OUTlistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

I had incredible luck with National's 50Khz series , LM2576 in D2T mode. It never gets warmer than 30C, and is 95% efficient, even operates down to bottom+1V! NO heat. A wonderful part. Be careful to use the inductor they recommend, to prevent flux saturation. It will still be working into the next century. --Bob At 03:24 PM 6/4/2003 +0100, you wrote: {Quote hidden}>Hi > >As part of a battery charging circuit I need to regulate the current. The >problem is I cannot lose the heat in the hand held device so need to use a >Switch mode Current regulator. I have found them to be very thin on the >ground. Can anybody recommend one? It needs to be capable of about 1500ma >at 5V (I am charging 4 AA NIMH batteries) > > >Many thanks > > >Tim > >-- >http://www.piclist.com#nomail Going offline? Don't AutoReply us! >email .....listservKILLspam@spam@mitvma.mit.edu with SET PICList DIGEST in the body --------------- NOTICE 1. This account can accept email & attachments up to 10M in size. 2. Federal Monitors: At request of client, some attachments are encrypted. Please DO NOT delay traffic; please reply with credentials for password. -------------- -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

You're probably looking for a buck converter, but I thought I'd point out a couple boost converters I looked at recently. The LT1618 is interesting in that it has a pair of high side inputs for measuring across a current sense resistor so you can do constant current regulation. It needs 50mV across the sense resistor. Unfortunately, the LT1618 could not output enough power for the application I had (dumping 10W, 7V at 1.5A into an LED), so I ended up using the LT1370. This does not have a current sense input. It needs something like 1.25V on the feedback input. I put a 40 milliohm current sense resistor in series with the load and amplified the sense voltage by 20 with a MAX4073TAUT-T sense amplifier. This drives the feedback input of the LT1370. Works well. About 5,000 units built so far... Finally, it'd be great if you could find a chip specifically designed for charging the batteries you're charging. In my application, we're using a pair of 2AH lithium ion cells in parallel. The LTC1733 linear charger does a great job. It handles dead battery conditioning, constant current charge, constant voltage charge, and time-out. You set the constant current with a resistor to ground on one pin. You can measure the voltage on that pin to determine the output current (I detect end of charge current watching that voltage with a PIC). Raising that pin voltage to 5V shuts down the charger. Nice chip! Harold Harold --- Eduardo Garcia <.....egnascimentoKILLspam.....YAHOO.COM.BR> wrote: Hello Timothy, Try MIC4576. It is a 3A switched buck regulator that may work cold at 1,5A. There are other switched regulators that need external transistors and other components so MIC4576 use a simplest circuit as well. Sorry my bad english but I hope you understood me. {Original Message removed}

Yes, LM2576 is also a good choice. Good Luck! ----- Original Message ----- From: "Bob Axtell" <EraseMEcr_axtellspam_OUTTakeThisOuTYAHOO.COM> To: <PICLISTspam_OUTMITVMA.MIT.EDU> Sent: Wednesday, June 04, 2003 11:36 AM Subject: Re: [EE] Switch Mode Current regulation > I had incredible luck with National's 50Khz series , LM2576 in D2T mode. It {Quote hidden}> never gets warmer than 30C, and is 95% efficient, even operates down to > bottom+1V! NO heat. A wonderful part. Be careful to use the inductor they > recommend, to prevent flux saturation. > > It will still be working into the next century. > > --Bob > > At 03:24 PM 6/4/2003 +0100, you wrote: > >Hi > > > >As part of a battery charging circuit I need to regulate the current. The > >problem is I cannot lose the heat in the hand held device so need to use a > >Switch mode Current regulator. I have found them to be very thin on the > >ground. Can anybody recommend one? It needs to be capable of about 1500ma {Quote hidden}> >at 5V (I am charging 4 AA NIMH batteries) > > > > > >Many thanks > > > > > >Tim > > > >-- > >http://www.piclist.com#nomail Going offline? Don't AutoReply us! > >email @spam@listservKILLspammitvma.mit.edu with SET PICList DIGEST in the body > > --------------- > NOTICE > > 1. This account can accept email & attachments up to 10M in size. > 2. Federal Monitors: At request of client, some attachments are encrypted. > Please DO NOT delay traffic; please reply with credentials for password. > -------------- > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email KILLspamlistservKILLspammitvma.mit.edu with SET PICList DIGEST in the body --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.486 / Virus Database: 284 - Release Date: 29/05/03 -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email RemoveMElistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body