Miniature DC DC Boost Converter - Page 1
Forum section: electronics / projects

author: Digibin
author_rank: Regular Contributor
timestamp: March 14, 2016, 09:59:40 pm
content: I have a requirement to add a DC DC boost converter into a space constrained application. Input is a Li-ion cell at around 3.8V and I need a fixed output of around 21V 50mA. There's a microcontroller in there with some available IO. So I can either use the micro to generate PWM and drive a boost converter (just adding the inductor, diode, switch, cap and feedback resistors), or I could use an off the shelf module. I'm aware of the small nano buck converter modules available from the likes of TI (nano series Simple Switcher power modules) and Murata (Micro DC DC Converters) but I can't find any miniature modules for boost converters which is a shame.This only needs to be quick and dirty - it's just a temporary proof of concept. Any advice on how to implement this in as small an area as I can and as quickly as I can?

author: ovnr
author_rank: Frequent Contributor
timestamp: March 14, 2016, 10:01:23 pm
content: What are you driving?

author: suicidaleggroll
author_rank: Super Contributor
timestamp: March 14, 2016, 10:09:52 pm
content: TI's WEBENCH power designer lets you input your operating conditions and then filter the resulting options by footprint size, BOM cost, etc. You might check and see if there are any solutions that fit your requirements.For 3.2-4.4 Vin, 21 Vout, and 50mA, the smallest one I see is 45 mm^2 using the TPS61046 at 76% efficiency.

author: Digibin
author_rank: Regular Contributor
timestamp: March 14, 2016, 10:13:51 pm
content: It's an LED array. So yes a constant current source would be better but for this it doesn't need to be - I suspect a simple voltage source would be quicker and smaller.And output ripple is not important, as long as it's not visible in the LEDs.

author: Digibin
author_rank: Regular Contributor
timestamp: March 14, 2016, 10:16:49 pm
content: Quote from: suicidaleggroll on March 14, 2016, 10:09:52 pmYeh I did look at that. An off the shelf module would be preferable to discrete circuit, purely for the sake of time and simplicity. If I roll my own boost converter circuit I'll probably just make it fairly crude and use the micro to control it.

author: ovnr
author_rank: Frequent Contributor
timestamp: March 14, 2016, 10:28:54 pm
content: If you're just driving LEDs, it's really pretty simple. Stick a current sense resistor on the low side and use that for feedback, then just slowly ramp up the PWM. And the LEDs will be fine with both ripple and a slow feedback loop.

author: Digibin
author_rank: Regular Contributor
timestamp: March 14, 2016, 10:39:04 pm
content: The LEDs are on a board that can't be changed so unfortunately I can't add a current sense resistor to it. Could do a high side but that involves more parts..

author: Digibin
author_rank: Regular Contributor
timestamp: March 15, 2016, 06:57:44 pm
content: Bump - curious if anyone knows of any miniature boost converter modules?

author: Apollyon25_
author_rank: Regular Contributor
timestamp: March 15, 2016, 08:55:18 pm
content: Have you searched Ti? LT? MPS? etc etc etc.How small is small??

author: m98
author_rank: Frequent Contributor
timestamp: March 15, 2016, 10:05:25 pm
content: Just needed to do exactly the same thing(the li-ion to 21V conversion), also a proof of concept, used the LTC3872.

author: technix
author_rank: Super Contributor
timestamp: March 20, 2016, 11:19:43 pm
content: MC34063 + SS34 + some SMD inductor. Small, cheap, and I think it will just cut it.