Help identify component - Page 1
Forum section: electronics / beginners

author: giosif
author_rank: Frequent Contributor
timestamp: May 23, 2022, 07:21:02 pm
content: Hi,I am trying to repair the analog board of a TTi PSA1301T handheld SA and I cannot identify the SOT-23-6 component marked with 744L in the picture below.This is located close to the RF input of the SA (but before the RF mixer).I am suspecting it might be some sort of analog switch, to select the different levels of attenuation, but that's just my (novice) guess.Anyone who can help identify the component, please?Thanks!

author: giosif
author_rank: Frequent Contributor
timestamp: May 25, 2022, 07:54:52 pm
content: Anyone any guesses?

author: Manul
author_rank: Super Contributor
timestamp: May 25, 2022, 08:41:16 pm
content: If you want guesses, here is mine: diode array for protection or RF switching. But I'm not familiar with this device, so really just a wild guess.

author: giosif
author_rank: Frequent Contributor
timestamp: May 31, 2022, 08:16:30 pm
content: Thank you for the input, but I am fairly certain it is a switch.But I feel I wasn't being fair when sharing the first photo, as it was hard to visualize the circuit section the component is part of.I have now included a (hopefully) better picture, with my notes added (please note I have desoldered one of two instances of this component).Based on the notes, I would think this is a SPDT analog switch, but what confuses me is:1. None of the SOT-23-6 SPDT analog switches I could find on Mouser, for instance, match the pinout of this component.2. Between the two instances of this component on the board, pins 4 and 6 are electrically connected, as well as pins 6 and 4, respectively.So, this sort of excludes the idea that one of these pins is for power and the other for the switch control.Any other ideas/suggestions?

author: gamalot
author_rank: Super Contributor
timestamp: June 01, 2022, 03:27:09 pm
content: I didn't double check, but it looks like HMC544 has the same pinout as the device you're looking for.https://au.mouser.com/datasheet/2/609/hmc544ae-772755.pdf

author: giosif
author_rank: Frequent Contributor
timestamp: June 01, 2022, 04:10:03 pm
content: Thank you!Funnily enough, I also found the same just this morning:Analog Devices HMC221BE or HMC544AE or HMC545AE or HMC595AESkyworks Solutions AS193-73LFThe secret was to search for "rf switch sot-23-6", rather than "analog switch sot-23-6" that I had used before.None of the above components match the markings on mine, so I don't have an exact match yet, but it is very much confirmed we are looking at a SPDT switch.

author: gamalot
author_rank: Super Contributor
timestamp: June 01, 2022, 04:17:57 pm
content: Quote from: giosif on June 01, 2022, 04:10:03 pmYep, that's how I searched. Obviously the marking pattern in your picture is very similar to ADI's HMC series chips, and completely different from Skyworks.

author: DavidAlfa
author_rank: Super Contributor
timestamp: June 01, 2022, 04:50:21 pm
content: Might be useful: Search "Active SMD semiconductor components marking codes DATABOOK 2019" in Google.Second result (ebin.pub). If for professional/lucrative use, I'd encourage buying it!

author: giosif
author_rank: Frequent Contributor
timestamp: June 01, 2022, 06:43:43 pm
content: Quote from: gamalot on June 01, 2022, 04:17:57 pmI noticed that as well, although there is no 74x series switch that I could find.

author: giosif
author_rank: Frequent Contributor
timestamp: June 01, 2022, 06:46:37 pm
content: Quote from: DavidAlfa on June 01, 2022, 04:50:21 pmI am guessing you are a user of this book, since you are recommending it.In this case, could you please check if the 744L is listed there?I am only asking for confirmation the entry exists and, if it does, I will consider buying the book.If there is no such entry, I think I will continue to rely on Google searches, plus the video Dave released just a few days back on this very topic.

author: DavidAlfa
author_rank: Super Contributor
timestamp: June 01, 2022, 06:53:13 pm
content: Nope, not that one.I very rarely use it, most of the time google helps fast enough. Perhabs twice a year.

author: gamalot
author_rank: Super Contributor
timestamp: June 01, 2022, 06:54:32 pm
content: Quote from: giosif on June 01, 2022, 06:46:37 pmThe short answer is NO.Actually you can find that book in zlibrary if you want.