| Electronics > Projects, Designs, and Technical Stuff |
| Batteroo testing |
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| razvanme:
--- Quote from: Wytnucls on December 23, 2016, 08:24:53 am ---Here is an attempt to identify the DC to DC converter IC (I find it unlikely that they would have developed their own IC at that price point). There are no resistors to set the output voltage, so it is probably a fixed voltage output IC (~1.5V), which usually comes in a 6 pin package. This one has 8 pins. A 2.2uF inductor usually means a switching frequency of 2MHz for similar ICs. The picture is a bit blurry, but here my best guess for the PCB topology and pin functionality: Feel free to chime in if you spotted other connections --- End quote --- The Red Vout in your image is actually Ground. The IC is mirrored. VIN is on the Left. --- Quote from: bktemp on December 23, 2016, 10:10:23 am ---Therefore my guess would be it is a customized version, so even the pinout could be customized. --- End quote --- Don't think it's a custom chip, what's the point of having 3 grounds and 2 unconnected pins. They could have done a 4 pin chip. |
| MatthewEveritt:
--- Quote from: EEVblog on December 23, 2016, 04:40:05 am ---I have one of these single AAA toy trains. http://www.toysrus.com/buy/preschool-trains/imaginarium-power-steam-engine-train-set-5f5eedb-12595303 Will do the same test as Frank did. Thought about getting two and running side-by-side but then people might complain the trains aren't identical. So will run two tests and then edit side-by-side footage with timer. Maybe add a lap counter? --- End quote --- If you record time per lap you can look at how the train slows down - might be interesting. Toyboy discharge curves. :) |
| bktemp:
--- Quote from: razvanme on December 23, 2016, 11:18:01 am ---Don't think it's a custom chip, what's the point of having 3 grounds and 2 unconnected pins. They could have done a 4 pin chip. --- End quote --- GND is the most critical pin: During switching the current ramps up slowly and then abruptly drops to zero when the switch turns off -> You need a good connection to GND with low parasitic inductance. In your drawing the two left GND pins are probably power GND (short connection to input capacitors), while the right GND pin could be signal GND for sensing the output voltage (short connection to output capacitors). It would be interesting to see if both NC pins are really not connected or if they are unused functions like undervoltage detection, power good, enable or similar usual functions. I don't think it is a completely custom silicon, but maybe a customized version (output voltage set to 1.5V and maybe custom pinout). Many manufacturers offer customized voltage options in addition to the usual output voltage version. |
| mikeselectricstuff:
A crude motor load like this may well cause confusion to the regulator - might be interesting to look at the voltage waveform on the output & input current. With such a difference in lifetime, a question is where is the energy actually going - batteriser heating? motor heating? Or maybe just crapping out early - might be interesting to take the battery out of the sleeve and see how long it will then run the train by itself. |
| amspire:
The IC is not a long way off the Linear Technology LTC3539/LTC3539-2 http://cds.linear.com/docs/en/datasheet/35392fc.pdf If it was an IC with the same pinout, then pins 8, 7, and 6 would be connected together on the output. Pin 4 would connect to the input and the indictor. Pin 1 to the other side of the inductor. Pins 2 and 3 -ve (that is the one that looks wrong). It is possible they have gone to LT, or even a chinese company who makes LT copies and have changed the packaging/pinout slightly for some reason. There are differences. The ripple in burstmode from the LT device is 20mV whereas the Batteriser is 200mV but has a lower quiescent current. |
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