chinese 120V Buck DC/DC converter - chip search - Page 1
Forum section: electronics / projects

author: jmibk
author_rank: Regular Contributor
timestamp: September 23, 2022, 12:50:21 pm
content: I bought some of those cheap 120V in to 5V 2A or 3A output DC buck converters.https://www.aliexpress.com/item/33014367277.html?spm=a2g0o.productlist.0.0.46792eeeY6vAFl&algo_pvid=68456e68-51a7-4e8c-887c-c3f8ebda72ba&algo_exp_id=68456e68-51a7-4e8c-887c-c3f8ebda72ba-5&pdp_ext_f=%7B%22sku_id%22%3A%2267179048140%22%7D&pdp_npi=2%40dis%21EUR%215.11%213.32%21%21%21%21%21%40210318cf16639369713785395e9e90%2167179048140%21sea&curPageLogUid=0rY1S2RNT4TuI'm interested in the chip that is used here, because:- it has a wide input voltage range,- a relatively high current without any additional mosfet and- it must be cheap.I got 2 modules, one with 5V / 2A output, that doesn't have a heatsink on it and a second one with 5V / 3A output with an aditional switching FET.On both board they completely rubbed the numbers off - so I can't identify the chip.Its a SOT8 job. Some of these boards available in china are also only 90V input (but they look the same as the 120V versions).I searched through the usual catalogues of digikey, mouser and so on, but nothing fits the data.Does someone know, what chip it is? I like to use it in some own projects with different voltages without buying these modules and wacking them onto a board.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 23, 2022, 01:20:44 pm
content: Quote from: jmibk on September 23, 2022, 12:50:21 pmYou'd be better off looking at LCSC - they list a couple at 100V, maybe look at that manufacturer's website for othershttps://lcsc.com/product-detail/span-style-background-color-ff0-DC-DC-span-Converters_XDS-TX4130L_C448635.html

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 23, 2022, 01:26:47 pm
content: Even higher voltage nonisolated buck converters chips exist, for auxiliary power supply applications. Those are usually used as part of larger power supplies to power the control logic independent of what the main output is doing.https://www.power.com/products/linkswitch/linkswitch-tn2

author: thm_w
author_rank: Super Contributor
timestamp: September 23, 2022, 10:46:22 pm
content: These modules are $2 each, the chance that you'll be able to source the parts and build it into your own design for less is basically zero.XL7046 will do 80V:https://datasheet.lcsc.com/lcsc/2110181830_XLSEMI-XL7046E1_C2843193.pdfXL7056 100V:http://www.xlsemi.net/datasheet/XL7056%20datasheet-English.pdfXL7010 seems higher but maybe an old part

author: jmibk
author_rank: Regular Contributor
timestamp: October 31, 2022, 12:00:48 pm
content: The TX4130L was the correct part I was searching for - thanks for your time (at all)!Can someone tell me, what weird feedback system this regulator uses? Attached a schematic, that is used for around 5V.Ignore the values in orange. Red are the (DC) voltages when running.I like to extend the circuit to get 12V at the output (with a higher input voltage of course).The datasheet is most of it in chinese, I can't find any in english.

author: thm_w
author_rank: Super Contributor
timestamp: November 01, 2022, 12:02:54 am
content: The datasheet tells you the feedback equation:Output voltage setting: Vout=(R2+R4)/R4*VFBR1 = R2, R3 = R4Does that work?VFB1(+) to VFB2(-) is 0.38V

author: jmibk
author_rank: Regular Contributor
timestamp: November 01, 2022, 05:25:16 pm
content: Thanks for the datasheet in a readable language. I donn't find that on google or I was blind.I got the equation like you said, it is also in the datasheet. The quirk with the VFB1 to VFB2 is not obvious.But at the end I choosed R2 = 48k and R4 = 1k5 and I got an output voltage of 12,7V. That works for me.

author: thm_w
author_rank: Super Contributor
timestamp: November 01, 2022, 10:17:56 pm
content: Quote from: jmibk on November 01, 2022, 05:25:16 pmYeah never seen FB done like that.You can use this to translate:https://translate.google.com/