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 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 ----- From: "Timothy Box" To: Sent: Wednesday, June 04, 2003 11:24 AM Subject: [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 listserv@mitvma.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 listserv@mitvma.mit.edu with SET PICList DIGEST in the body ________________________________________________________________ The best thing to hit the internet in years - Juno SpeedBand! Surf the web up to FIVE TIMES FASTER! Only $14.95/ month - visit www.juno.com to sign up today! -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body