Please help to identify this switching regulator? Film LED dmx controller  - Page 1
Forum section: electronics / repair

author: cozza
author_rank: Regular Contributor
timestamp: July 25, 2025, 01:18:16 am
content: Hello all, I am having trouble identifying this SOT23-5 part from the usual lookup websites, and image searches. If anyone can ID it, that would be much appreciated!It is presenting as dead short on output, confirmed by removing it. I have confirmed the micro and display are good with an external supply.Package is marked :20029190No luck finding the device in parts lookup tables, it may be an abbreviation of an actual part number perhaps?There is a date on the PCB silkscreen of 2021-04, so the 2002 may be a date code.Pinout is1 : either power good or enable2 : Ground3 : Switch out to inductor4 : Vin5 : Feedback ( resistive divider with 92k to output, 56k to ground ) measured in circuitAppears to be converting main regulated 5V to 3.3V for microcontroller / wireless DMX transceiverAny help would be amazing, thank you.

author: amyk
author_rank: Super Contributor
timestamp: July 25, 2025, 02:09:51 am
content: What are the dimensions of the package? Are you sure it's SOT23-5?

author: fzabkar
author_rank: Super Contributor
timestamp: July 25, 2025, 02:20:10 am
content: Can you determine the FB voltage?I suggest you switch your DMM to diode mode and connect your probes between the top and bottom ends of the potential divider. Then use a second DMM to measure the FB voltage and the voltage at the top of the divider. Now multiply 3.3V by the ratio of the two measured voltages and that should give you the IC's FB spec.

author: langwadt
author_rank: Super Contributor
timestamp: July 25, 2025, 02:39:52 am
content: do you need an exact replacement? plenty of buck converters that fit that pinout, but afaict most of them with 0.6V vref so you'd need to change the divider

author: cozza
author_rank: Regular Contributor
timestamp: July 25, 2025, 03:45:51 am
content: Hi Amyk. Dimensions check out with a vernier for SOT23-5Hi Fzabkar. Feedback voltage is 0.593V with 3.3V externally supplied.Hi Langwadt! Any substitute suggestions are also be welcome, thank you. The current drawn is 140mA when active.

author: cozza
author_rank: Regular Contributor
timestamp: July 25, 2025, 03:54:22 am
content: The enable pin connects to a 10k resistor which is connected to the 5V rail from the upstream regulatorInductor is unmarked but measures 1.2uH at 1kHz (highest frequency of my LCR meter..)

author: fzabkar
author_rank: Super Contributor
timestamp: July 25, 2025, 04:06:43 am
content: Quote from: cozza on July 25, 2025, 03:45:51 amI was being careful. My concern was that there may have been other damage on the 3.3V rail.That said, I would think that there should plenty of alternative candidates, if you can't identify the original.Sometimes it helps to identify other ICS, in case the designer has chosen the same manufacturer for the others.

author: cozza
author_rank: Regular Contributor
timestamp: July 25, 2025, 04:44:39 am
content: The 5V regulator is a MP4560 (SOICby Monolithic Power Systems, have found a pin compatible part for the SOT23-5 footprint in their catalog which may be OK, the MP2128DT.

author: langwadt
author_rank: Super Contributor
timestamp: July 25, 2025, 10:55:05 am
content: Quote from: cozza on July 25, 2025, 03:45:51 amTLV62569