Finding a switch mode regulator? - Page 1
Forum section: electronics / projects

author: lincoln
author_rank: Regular Contributor
timestamp: April 19, 2016, 08:41:38 pm
content: Hello Gents,I'm on the Digikey / Mouser / ect design marry-go-round. I'm working on a box that is 90% digital and has a number of voltage rails. The two main rails (current wise) are 3.3 and 1.8 I'm targeting switch mode regulators. The other regs (2.5, 1.2, 1.0) are are relatively light (100 ma or less) or supply a single chip so i'm planing to use linear for them.I am looking for a buck converter with : Iout = 1~3A, Vin > 12vdc, vout = 1.8, and has an oscillator sync input.I'm hoping to use switching frequency 900k or above to keep the inductors small.What do you think? Whats you favorite switching regulator?

author: ZeTeX
author_rank: Frequent Contributor
timestamp: April 19, 2016, 08:53:53 pm
content: Quote from: lincoln on April 19, 2016, 08:41:38 pmhave you tried looking here?http://www.linear.com/parametric/Switching_Regulator#!1646_Buck!1032_%3C=10!1033_%3E=15!1105_%3C=1.8!1034_%3E=1.8!1107_3:9!vinmin_10!vinmax_15!vout_1.8!iout_3!vout2_!iout2_!vout3_!iout3_

author: lincoln
author_rank: Regular Contributor
timestamp: April 19, 2016, 10:45:41 pm
content: Linear is a good go to, found two possible parts but a little on the expensive side but they tick all the other boxes. looking at LTC3601 / ltc3621-2Most of the parts that come up are not well distributed. If I punch in a part to findchips.com and I can't find two outfits that has more than 1k in stock, i'm nervous. For an OCXO sure I am willing to jump through hoops / deal with small distributors / lead times. I really don't want to do that for a voltage regulator that we are going to buy 500 / year¯\_(?)_/¯

author: Wobbegong
author_rank: Newbie
timestamp: April 19, 2016, 11:34:09 pm
content: RT7296DGJ8FCT-NDhttp://www.digikey.com/product-detail/en/richtek-usa-inc/RT7296DGJ8F/RT7296DGJ8FCT-ND/5640533?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 19, 2016, 11:53:29 pm
content: TPS54140, TPS54233, and similar parts in the range, would probably be a nice fit.Tim

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: April 20, 2016, 04:02:34 am
content: How about the LT8614? It can do 4A, operates above 1 MHz and has a sync input. I've used it to power low noise RF synthesizers with a clean-up LDO - TPS7A8101, with a reference bypass (aka "noise reduction") capacitor. Worked quite well, the 3.2 GHz synthesizer measured about -110 dBc/Hz at 1 kHz offset.Apparently they now have an LT8640 that can do 5A as well.

author: Thomas
author_rank: Regular Contributor
timestamp: April 20, 2016, 05:21:29 am
content: Go to TI and find their Webench Designer:http://www.ti.com/lsds/ti/analog/webench/overview.pagePut in your numbers and BAM - your design is ready

author: John_ITIC
author_rank: Frequent Contributor
timestamp: April 20, 2016, 05:46:57 am
content: Quote from: T3sl4co1l on April 19, 2016, 11:53:29 pmI'm using the below, which were the smallest I could find.Switched for high powerTPS54418 (1.8V, 4A)TPS54418 (0.9V, 4A)TI SwitcherPro Software:http://www.ti.com/tool/switcherproSwitches at 1 MHz (2 MHz too, if I recall correctly).LDO for low power / lowest noiseTPS74701 (1.1V, 500mA)TPS74701 (1.5V, 500mA)TPS74701 (2.5V, 500mA)Note these are all configurable so only two part numbers for all power rails.

author: Jeroen3
author_rank: Super Contributor
timestamp: April 20, 2016, 06:16:11 am
content: What quantity are you looking for?

author: lincoln
author_rank: Regular Contributor
timestamp: April 21, 2016, 03:17:54 am
content: Quote from: Jeroen3 on April 20, 2016, 06:16:11 am500 - 1k this year, 3 to 5K next year,Thanks for the suggestions, I'm working through the list.

author: Jeroen3
author_rank: Super Contributor
timestamp: April 21, 2016, 04:21:23 am
content: I think you're right on the edge regarding cost effectiveness of custom design.For low quantities I always use dc/dc bricks. Saves a lot of risk and time. But is more expensive.