Identifying Unknown SMD Components – Best Practices? - Page 1
Forum section: electronics / projects

author: miette_Kruemelchen
author_rank: Contributor
timestamp: February 20, 2025, 06:18:35 am
content: Hello everyone,I’m not looking to repair a faulty panel but rather to understand the general approach to identifying SMD components when they cannot be found through conventional search engines or common component databases. I’m currently facing this exact issue with the following components:1️⃣ Component 1Package: TSSOP-10 / SOT-552-1 (8-pin SMD IC)Marking:Top line: 1780Bottom line (underlined): H705Suspected function: Step-down/step-up converterBehavior in circuit: The input voltage (3.3V from the mainboard) is immediately pulled down when applied, drawing a very high current (1.5 A), and the IC gets extremely hot.2️⃣ Component 2Package: TSOP-5 / SOT-753Marking: DH-K18No further information found3️⃣ Component 3Marking: E16A9Suspected function: Voltage regulator for 3.3V on a mainboardI have encountered similar components on circuit boards before but often struggle to find datasheets or manufacturer information. Some of these ICs appear on platforms like Alibaba or Aliexpress, but without detailed technical specifications.So my question is: What methods do you use to identify components with unknown markings? Are there any specialized databases !I’d appreciate any tips!Best regards,Sven

author: KE5FX
author_rank: Super Contributor
timestamp: February 20, 2025, 06:53:15 am
content: I usually checkSMD Codebook(.pdf),https://smd.yooneed.one/, orhttps://www.s-manuals.com.You can also try LLMs, but they are hit or miss. For the first one, o1-pro thinks it's a SN65HVD1780 RS-485 transceiver, but I don't see any reason to think that's right. o4 thought it was an apparently-nonexistent AOZ1780 from Alpha & Omega Semiconductor, which admittedly would make sense if it were a boost or buck converter. Gemini says check EEVblog.

author: miette_Kruemelchen
author_rank: Contributor
timestamp: February 20, 2025, 07:24:44 pm
content: Hi KE5FX,Thank you for your helpful suggestions and the links! I will definitely check the SMD Codebook as well as the websites smd.yooneed.one and s-manuals.com to gather more information.The idea of AOZ1780 as a Boost/Buck Converter is definitely interesting. I will continue to explore these possibilities and see if I can find more on the topic.If I find any new information, I'll be sure to keep you updated.Thanks again for your support!Best regards,Sven

author: miette_Kruemelchen
author_rank: Contributor
timestamp: February 23, 2025, 08:58:10 am
content: Hello EEVBOLG Forum members,Yesterday, I desoldered the IC labeled"1780"that I had been looking for. It is likely a Step-Up (Boost) converter. This IC is located on an LCD panel and is probably responsible for generating theVAA voltage.The IC’s connections are as follows:Pin 8:Connected to an SMD capacitor, with the other side grounded.Pin 7:Connected to a 1 kΩ resistor, whose other end leads to Pin 6.Pin 5:Likely the operating voltage and is connected to VCC via an inductor (L).Pin 4:GND.Pin 3:Connected to a 9.9 kΩ resistor, whose other end also leads to Pin 6.Pin 2:Connected to an SMD resistor labeled "15 c," which measures 12.19 kΩ. In series with this resistor is another labeled "91X," which measures 87 Ω. The other end of this resistor is grounded. Additionally, there is a resistor labeled "913" connected to Pin 2, whose other end is connected to the cathode of an SMD diode (code K77 or K79). The anode of the diode is connected to the aforementioned inductor and leads to VCC.At the cathode of the diode:Three capacitors are connected in parallel, likely to stabilize the VAA voltage. The PCB has the label "VAA."Pin 1:Connected to a capacitor, with the other side grounded. Another capacitor is connected to this pin, and its other end is connected to a 30 kΩ resistor that leads to ground.Additional information:I have also gathered some additional information about the panel:The panel measures205 mmin height and260 mmin length.The IC labeled"1780"has dimensions of3.1 mmin length,2.9 mmin height, and0.89 mmin thickness, as measured with a caliper.The PCB, where the IC 1780 is mounted, is labeled:Yang An YA-4A 94V-0 E114139, with a symbol of a circle containing"e1", followed by a rectangle with"m"inside it. Next to this, the label"N121X5-L01xX"is printed.There is also a small sticker with two Chinese or Japanese characters and the label“LO1” or “L01”(the last part is unclear). I will send you a picture so you can take a look at the characters.Control electronics:On the control electronics, there is a large SMD IC. The first line reads"CH I" and "ME I".The second line says"CM1715".The third line shows"706F-01ESSG80B7H".The fourth line reads"PA5528 FB TWN".Unfortunately, I haven't found any further information.I’d appreciate any tips!Best regards,Sven