Looking for spear part - Page 1
Forum section: electronics / beginners

author: mathk
author_rank: Contributor
timestamp: November 24, 2011, 08:50:38 am
content: Hi everyoneGot an issue here with a 4d-System uCam-TTL. I coincidentally invert the voltage and some smoke cam out of it.Now the motherboard is not working anymore but I think that there is only a small chip that get burn. Unfortunately I did not found out the part in any datasheet-websit-lookup. The component is a SMD that look like a voltage regulator. It look like the LM1117 SMD. But on top of it it is written 7333-A. Does someone can help me to found a spare part of it?Many thanks

author: IanB
author_rank: Super Contributor
timestamp: November 24, 2011, 08:57:10 am
content: Is it an AP7333 linear regulator?

author: mathk
author_rank: Contributor
timestamp: November 24, 2011, 10:20:43 am
content: It might be that but it really look like the LM1117 SMD, it got 3 pin on one side and a larger plate on the other.1.http://www.sparkfun.com/products/595,

author: Unknown
author_rank: Unknown
timestamp: November 24, 2011, 09:48:25 pm
content: That's a standard SOT-223 footprint, nothing LM1117-specific about it. Not sure if the AP7333A is available in SOT-223, can't find it on Digikey or Findchips, but that does not mean it's not used by the millions by some big Chinese OEMs. Digikey has about 500 different LDO regulators in SOT-223 in stock, so finding a proper replacement shouldn't be difficult. Assuming it's indeed an LDO regulator, but that should be obvious from the circuitry around it. The voltage is also important, these regulators tend to be available in several fixed voltages and sometimes a variable voltage set by a resistive divider.Stability with ceramic output capacitors might be an issue, I don't think the LM1117 is specced for ceramic caps. The specs seem fairly typical for a modern MOSFET-based LDO, like the MCP1800 series.

author: IanB
author_rank: Super Contributor
timestamp: November 24, 2011, 10:00:15 pm
content: Quote from: alm on November 24, 2011, 09:48:25 pmActually the AP7333 part doesn't have an A suffix, it has a variety of longer suffices depending on the specs (so the part in question might not be that one). Searching for AP7333 on FindChips gets lots of results however.

author: Unknown
author_rank: Unknown
timestamp: November 24, 2011, 10:52:21 pm
content: You're right about the A suffix, although it may be used by a manufacturer that does not sell to western customers in small quantities. All of the AP7333 hits are SOT-23, as far as I can see.If it's indeed a linear regulator, I would expect it to be connected to a 5V supply, or battery with a voltage between 3.6 and 5.5V or so, on one side, and to some lower voltage (eg. 1.8/2.5/3.3V) parts on the other. Plus caps between ground and the input and output terminal. And the reference terminal should be connected to ground if it's a fixed voltage one.

author: ElektroQuark
author_rank: Unknown
timestamp: November 25, 2011, 08:58:24 am
content: Can you read what is marked on the part?

author: mathk
author_rank: Contributor
timestamp: November 25, 2011, 09:26:03 am
content: Thanks a lot for all the precision guys.@EdoNork It is written 7333-A.@alm Actually the spec of the uCam says that it should be powered by 3.3V but 5V is also acceptable.There is some caps around the chips so I guess you are correct about the LDO regulator. I will send a photo of it so that would be more clear. Now I have to found out the correct output voltage...Btw I have sent a email to 4d System support and the answer was: We don't know, lookup in google!!.Funny way to answer.

author: ElektroQuark
author_rank: Unknown
timestamp: November 25, 2011, 09:44:51 am
content: Quote from: mathk on November 25, 2011, 09:26:03 amSorry!Forgot to take my coffee this morning!!!Waiting for the pic.

author: mathk
author_rank: Contributor
timestamp: November 26, 2011, 05:59:47 pm
content: Here is the photo, it is the chip mark u2 :