My box of 140 USB power supplies arrived today
Wife wasn't too chuffed to see them
These power supplies are the type that have a common power block and optional connectors to suit various countries, so making the unit a universal travel charger. I paid GBP9.99 inc postage for a box of 140 as they are missing the connectors. Thats 7p each
I wasn't expecting much but they have turned out to be quite interesting. The unit produces 5V @ 700mA according to the label but I have not tested one yet.
The units look well put together and helpfully have tri-wing screws holding the case together instead of the welded construction so common these days. Upon opening the unit I was horrified to see a single transistor sitting amongst several other components.......but I jumped to an incorrect conclusion. Upon turning the PCB over I found a cluster of SMT components including a 'TH2267.1' 8 pin chip. I believe this chip to be the switching controller for the transistor. The switching transistor drives a decent looking little ferrite transformer. The transformer appears to have some sort of feedback winding that goes to the TH2267.1 chip (for output regulation?).
At the secondary of the transformer a single diode is used to rectify the ac and this is smoothed with a 470uF capacitor.
I did a quick search for the TH2267.1 and had quite a surprise when I found that many people wanted the same information but the chip is custom and Melexis Will not release any information at all, including its function ! See below from the Melexis FAQ site:
FAQs by Topic
TH2267.1
Q: Do you have anybody datasheet or same information about IC "TH2267.1" 8pins, SOP-8.
A: The requested datasheet can not be provided to you because the TH2267 is a custom specific product and therefore not open for everybody like our ASSP's listed on our web site.
Q: Why won't you guys make a datasheet available for this TH2267.1 chip. It's used in lots of Nokia cellphone chargers and a bit of info would help a lot of people who want to repair these things!
A: For customer specific parts like this one we have a contract with our customer in which is stated that we are not allowed to disclose any information without their permission.
Q: Is it possible to inquire about the approximate price of your product TH2267.1?
A:This is also confidential information which we cannot disclose.
Q:Can anybody please tell me what this IC TH2267.1 is doing at all?
A:We are not allowed to even disclose the function of the IC.
Finally the design looks decent enough, but the PCB track layout looks a little wild for my liking. The SMPSU case has several safety markings and indicates that the unit was manufactured in Germany. I was hoping to modify some of the 140 units for other usefull voltages for use in little projects. It would appear the TH2267.1 may have burst that balloon
I will try to work out its functionality via teh circuit around it. I have a few that I can risk in order to experiment on the design
All good fun
Apologies for the overexposed pictures, they were taken in a hurry.
Aurora