Electronics > Repair

Component ID - 6 pin DC-DC Stepdown

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55MV:
Hi!

I have a Dahua NVR4116-4KS2/L NVR which runs on 12V. One of the small DC-DC stepdowns got damaged and I need to replace it. I have multiple units so it was quite easy to check another and figure out some of the pinouts. I have included an image here of a good board and it contains the details I have figured out.U14 is the one I need to replace however both in the image are identical, just different resistors I assume to get the different output. Checking various websites with SMD codes, none seem to match what is on these boards - TV6RG.

Any help/insight provided will be greatly appreciated!



fzabkar:
SY8121B, Silergy, High Efficiency Fast Response, Synchronous Step Down Regulator, 2A, 4.5V - 18V Input, 1.2MHz, marking TVxyz, SOT23-6:

https://file.elecfans.com/web2/M00/46/61/pYYBAGKUGIyALgTxACvSJxie1eI897.pdf

https://images.tuyacn.com/smart/demo_printer/SY8121BABC.pdf

55MV:

--- Quote from: fzabkar on May 31, 2024, 08:07:14 am ---SY8121B, Silergy, High Efficiency Fast Response, Synchronous Step Down Regulator, 2A, 4.5V - 18V Input, 1.2MHz, marking TVxyz, SOT23-6:

https://file.elecfans.com/web2/M00/46/61/pYYBAGKUGIyALgTxACvSJxie1eI897.pdf

https://images.tuyacn.com/smart/demo_printer/SY8121BABC.pdf

--- End quote ---

Many many thanks! This looks like it. One thing I should do is stick the scope on one of the working units and determine the switching frequency and see if it matches up. Would the 3.3v on pin4 have just been the high signal to keep the chip in the on state? In theory I should be able to measure the output voltage on the LH side of the inductor. I will order a couple of these SY8121B and ill be sure to post an update once installed.

fzabkar:

--- Quote from: 55MV on May 31, 2024, 08:41:09 am ---Would the 3.3v on pin4 have just been the high signal to keep the chip in the on state?
--- End quote ---

Yes, that's what it does.

55MV:

--- Quote from: fzabkar on June 02, 2024, 01:31:02 am ---
--- Quote from: 55MV on May 31, 2024, 08:41:09 am ---Would the 3.3v on pin4 have just been the high signal to keep the chip in the on state?
--- End quote ---

Yes, that's what it does.

--- End quote ---

Awesome. I found this chip actually supplies a 1.5V rail on the output inductor. The replacement chips were indeed the same and worked great. Thankyou again.

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