Hello everyone, I have a micro2440 board. Yesterday, I had a serious problem, the 5vdc was short-circuit. The micro2440 is damaged, it seems that the ic 1.25V regulator went down. I want to replace it but I don't know its name. On the board, its name is ak42 but when i'm searching on the net, there is no matched result. I'm very thankful if someone have infomation about this ic! Thanks very much
ak42 will be a shorten form or a manufacturer's code for the part, I doubt if Google could find that. Do you not have a schematic for micro2440? Is there one on the downloads page?
According to the schematic it is a low dropout voltage regulator from Maxim. A MAX8860EUA18
Hi davef, Thanks for replying me. I've already had it. It use max8860 with 8 pins. But my micro board use ak42 with only 5 pins, so it isnot that one.
5 pins. We use the NCP3555A, one from Analog devices and another from TI (TPS series). I will try to get you the part numbers for their 1.25V variants about 11 hours from now, when I go to work. Dave
Are you referring to the micro2440 itself or the SDK carrier board? On that there is an LM1117-1.8V Dave...
The NCP3335A only goes down to 1.5V The TPS79301 is in a 5 pin leaded package, but it is an adjustable member of the TPS79XX series. The rest of this TI series only go down to 1.8V fixed. http://www.analog.com/en/power-management/linear-regulators/products/ind... Then there is Linear Technologies. Good luck!
Thanks Dave, I've just attached the image. I want the one on the micro board, not the SDK carrier. So it's NCP3335A or TPS7301, I want to know exactly so that I can replace it. Once again thank you very much!
any new infos please!!!!
Sorry, but I don't stand a chance of identifying that part either from the photo or case marking. I looks like a common package used for these LDOs. Both the NCP3335A and TPS7301 are adjustable, therefore I do not recommend them for your application . . . unless you know what you are doing you could blow up whatever you are supplying with 1.25Volts. The other problem with the NCP part is that it is not in the that package, I got that wrong. We have evaluated a ADPxxx part from Analog Devices they seem to have a wide range of parts. These parts are usually quite robust. Do you mean your 5Volt supply shorted and placed a high voltage on this 1.25V regulator? So, now there is ZERO volts on the output of this LDO? I am home now, do you want me to track down the part number of these Analog Devices parts? Also, it seems the manufacturer needs a "prod" to publish a relevant schematic.
Dear Dave, I'm very sorry for taking your time. Like I said before, when I was testing micro2440, the 5 Vdc was short-circuit. Then the micro's image worked wrong. I couldn't boot supervivi to load the new image. When I switched from nor, all 4 led light up. The 5vdc worked well on the board, i thought that the U3 ic(in the image) is damaged. So I need to replace it. I've been searching for information at last few days. So, i'm going to the forum to post this. If it take you much time, you can do other work. Perhaps, there are other people who know about this. Thank you very much!
Do you have a multi-meter? Can you check the voltages on the board? A shorted 5V supply should not cause a real issue. The input to the U3 regulator should be 3.3V U4 on your board is the 3.3V regulator. This takes the 5V input and generates 3.3V I would check for this 3.3V first. Dave...
Dear Dave McLaughlin, I've already checked it, the 3.3V is ok but 1.25 is down. There are test point on my micro. Thanks for you advice
Hard to understand how the 3.3V regulator is still alive and the 1.25V is dead after any fault on the 5V supply, either due to high voltage or being shorted to ground. Had a look on the Analog Devices site they don't have any 1.25V regulators. 1.2 or 1.3V they have. Is this for the core voltage on the uP? What are the tolerances for whatever it is supplying?
Judau, The ADP3331 part I was thinking of has 6 leads :( The LT1761 series from Linear Technologies look to be in the package you require, but again no specific 1.25V parts. I suspect that it is really an adjustable regulator like the MAX8860EUA18. Are there a couple of resistors like R33 and R32 around the device? I would get one of the adjustable varieties from Analog Devices or Linear Technologies and build a little test pcb in order to set the part up correctly and only then transfer the parts to the micro2440 or just wire it in. Maybe some day someone will find out where to get a replacement part. Check the s3c2410 datasheet for the voltage limits on the 1.25V supply. Dave
Dear Davef, One of my friend has known it. Perhaps it's XC9216. I found the datasheet and they seem similar. Thanks for your help lasts these day!
That part is different technology than the any of the parts mentioned so far. It is a switching or buck converter (Synchronous Step-Down DCDC Converter). More efficient than LDOs. Can't get the datasheet without registering. As long as the rest of the required passive components are on the board and the correct values looks like you finally got the answer. Hope it works out for you.
I am not convinced that this is an XC9216. If it is, it should have an inductor connected to pin 5 but if I zoom your image, pin 5 appears to be connected to a power plane, possible ground. Unless of course the inductor is on the top side but I don't think it is because of the apparent plane connection to pin 5. If it is the XC9216 then pin 4 is the output but this doesn't appear to have a suitable thickness track coming from it. If you follow the tracking on the PCB, where does the 4K7 (R13) resistor connect to? Which pin? Dave...