Alternative to SN6501 - Page 1
Forum section: electronics / projects

author: luky315
author_rank: Regular Contributor
timestamp: July 22, 2015, 04:07:00 pm
content: I need a bunch of galvanic isolated voltages (5V, <10mA). A prototype with a TI SN6501 works fine, but I need to synchronize the switching frequency of multiple devices. Is there a syncronizable transformer driver out there?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 22, 2015, 04:42:44 pm
content: Get a custom transformer with an assload of secondaries?Or, why not just connect transformers in parallel?If you need more current, it might be reasonable to tack on some power transistors, or use a similar but alternate method (e.g., just drive the transformers with some transistors arranged in a good old fashioned multivibrator).Tim

author: Frant
author_rank: Regular Contributor
timestamp: July 22, 2015, 05:18:25 pm
content: Quote from: luky315 on July 22, 2015, 04:07:00 pmMAX13253 is similar, but with additional functions. You can choose between an external clock source and the internal one with optional spread spectrum. It has the Enable input, and fault detection/indication.

author: luky315
author_rank: Regular Contributor
timestamp: July 23, 2015, 08:22:54 am
content: Thanks. The MAX13253 looks great, but is a bit expensive... A Device like the SN6501 but without ther internal oscillator ("only" the 50% Duty cycle and Break-before-Make part) would be grat...Has anyone used more than 2 SN6501 (or similar) in close proximity?I fear to get in trouble with beat frequencys, but I haven't tried it yet.

author: Zero999
author_rank: Super Contributor
timestamp: July 23, 2015, 09:27:21 am
content: Why is it essential for them to be synchronised?You'll probably find it will work fine just using multiple SN6501s. It's certainly worth building a prototype.

author: luky315
author_rank: Regular Contributor
timestamp: July 23, 2015, 10:18:49 am
content: I have bad experiences with unsynchronized converters and high precision circuits...

author: Frant
author_rank: Regular Contributor
timestamp: July 23, 2015, 11:09:02 am
content: Quote from: luky315 on July 23, 2015, 08:22:54 amYou may want to consider the DCR01 series from TI (e.g. the DCR010505). It is expensive, but highly integrated (contains the transformer, the rectifier, and the output voltage regulator). Unfortunately, high performance stuff don't come cheap.

author: Jeroen3
author_rank: Super Contributor
timestamp: July 23, 2015, 12:13:51 pm
content: They work fine, as long as they are properly decoupled. Even with 4 of them on a board.You can however go into LT3999 pricing range.

author: luky315
author_rank: Regular Contributor
timestamp: July 24, 2015, 10:58:02 am
content: Thanks for the help!What are your recommendations for generating 2.5kV isolated +-15V (3-5mA is sufficient) and 3.3V (75mA)? I am not looking for the cheapest solution, but for a small and reliable one.

author: dom0
author_rank: Super Contributor
timestamp: July 24, 2015, 12:57:07 pm
content: If it's about precision-low-noise things... try a Royer/resonance converter?

author: Jeroen3
author_rank: Super Contributor
timestamp: July 24, 2015, 06:45:06 pm
content: Get a recom unregulated power converter brick. And do filtering and LDO afterwards to make it high precision.http://www.recom-international.com/home.htmlOr some other brand. But I'd mostly use recom because they also have some fancy (non-isolated) DC/DC converters as simple smps drop-ins. (9-72V to 5V for example)