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TPS61253A: TPS61253A

Part Number: TPS61253A

Hi, I got and assembled few pieces of TPS31253A. I tested 5pcs and all of the provided 4.7V instead 5.0V. deviation between samples were 0.02V - from 4.70 to 7.72. I tested in different loads from 0 to 0.5A with same result.

need a help

  • I found two mistakes in my message: 

    1: TPS61253A

    2. 4.70 to 4.72V

  • Hi Katz,

    Thanks for choosing TI's boost converter products.

    Could you please share the schematic and layout? 

  • Schematic is standard as in datasheet. Enable connected to On/Off switch.

    layout is different but it cannot explain stable 4.7V output

  • Hi Katz,

    What's the inductor saturation current level? Please use a Isat high enough inductor otherwise the inductance will reduce to a much lower level so it will affect the normal working..

    You layout is not good. Below picture shows the datasheet's recommended layout. Use wide, short tracks or polygon for power traces to reduce parasitic inductance, resistance. 

  • I'm using 0.56uH 2.8A inductor as recommended. That's inductor part number: 1285AS-H-R56M=P2

    Layout is really different. do you think layout may change outer voltage? Build new layout will take a time.

  • Hi Katz,

    What's the input voltage range for TPS61253A boost circuit? Please select the inductor saturation current high enough. The maximum input average current could be calculated with equation: Iin_avg=Vout*Iout_max/Vin_min/Effi.

    For example, if Iout_max=1.5A, Vin_min=3V, maximum input average current is 5V*1.5A/3V/0.9=2.77A, considering the 20~40% inductor current tipple, the suggested inductor saturation current should be 2.77A*1.2=3.3A. You can use this example to check.

    The layout would cause the Vout decreasing and inaccurate. We already met lots of similar questions and posts on E2E.

  • Hi Again,

    Today i did new testing and cleared for me few points.

    except my samples I have evaluation board for this TPS61253A. it's working excellent and gives me stable 5 V. I replaced inductor on this EVA board with my inductor and tested board. it is working same good as previously. I checked with scope pulse on both samples - EVA and my. it looks same with only difference of pulse height. On my sample pules  are 4.7V and on EVA board - 5V.

    Only difference I found is following: my samples marked 17NI and IC on EVA board marked X7NI. 

    In this connection i have a question - may happens that I got samples 4.7V (announced as available) and not 4.0V?

    By the way, 4.7V is very stable and keep to all Li-Ion voltage range. I tested from 4.2V to 3.0V.

  • I meant "not 5.0V"

  • Hi Katz,

    Good  to know that. 

    Are you sure the samples you are using is TPS61253A (fixed 5.0V version), not TPS61255A (fixed 4.7V version)? I'll check if I could find the information about the two markings and will let you know.

    After you get the 5.0V regulated output voltage, have you tried increasing the load current to a heavy load, will the output voltage still well regulated at 5.0V?

  • Hi Katz,

    The IC with marking X7N1 should be samples before RTM.

    The 17N1 is sample after RTM, should all passed ATE test.

    Please use IC with marking 17N1 for test. 

  • I don't sure what I have. I just know I ordered TPS61253A. How I can sure what i got? Can you find marking for 61255A? i did not find datasheet for this part.

    it is very important for me as I'm designing new device and have to be sure I can use this part. meanwhile it looks like i got wrong part...

  • Hi Zack,

    That's exactly a question - i just know what i ordered (from Mouser) but don't sure what i got. TPS61255 is not possible to order so' i could not mistake. How I can know what i have? do you know what printing on both options? May it be mistake of TI? or of Mouser?

  • Hi Katz,

    How many IC with marking X7N1 do you have now? Can you do more test with X7N1 and 17N1 IC to confirm the output voltage is 4.7V, not because of solder work?

  • X7N1 I have only one on evaluation board. 17N1 I have 6 assembled on PCB and few more does not assembled. I can try to replace X7N1 on EVM board with 17N1 and than test. EVM board has right layout. if it will give 5V - problem is layout. otherwise I got wrong IC.

    Will do it today.

  • It is unbelievable! I placed my samples 17N1 on EVM board and got 4.97V! so, only wrong layout bring so big different in output voltage, 

    issue is resolved but i cannot explain it.

    Thanks,

  • Hi Katz,

    Good to hear that.

    It's also possible that the 17N1 is not soldered on your board first time. You can try again. I'll close this thread now.