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TPS65290ZB short circuit

Other Parts Discussed in Thread: TPS65290

Hello e2e Community,

I am using the TPS65290ZB. In my test case VIN is 3.8V (should be later sourced by battery) and I want to power a display with 5V.

When I enable the BB and BB1 (R0 with 0x05) I can measure the default ~ 4.1V (0x33). Now I write 0x37 to R3 - everything is still working but as soon as I go higher than 0x37 the TPS caused a short circuit. As load I use a 2.2k resistor.

When I use 4.5V as VIN I get 5V (0x3C) without a short circuit. It also work when I reduce the 4,5V to 3,8V after I reached the 5V output Voltage.

I'm pretty sure the test case (VIN: 3.8V BB: 5.0V) worked with the EVM of the TPS.

The power supply has a current limit from 50mA. In my first circuit I use a battery as supply but with short circuit the TPS sourced every power line (LDO,BB,etc) with 4,xV an destroy the other ICs.

 

My layout/schematic is based on the EVM:

As coil I use the SRN4018-3R3M, which has nearly the same specifications as the ASPI-0418FS-3R3M-T3 from the EVM. I also replace my two 33uF (6,3V) capacitors withe the one from the EVM (10V) to exclude them as a source of error. I try the same with the coil but unfortunately I broke it while unsoldering.

I hope you have some ideas or hints for me!
 
Thanks
Andreas

  • UPDATE:

    i have re-designed  the board with the hope it would work now ... unfortunately this is not the case. I could reach 4,9V (0x3B) once by increasing the desired output voltage step by step via spi. The right layout for the PMIC seems to be a very critical point :(

    Now the point is reached where I no longer know what to do.

     

    Andreas

  • UPDATE #2:

    Now i build a third version of my breakout board with the capacitors and coil listed in the BOM at slvu906.pdf. Also i ordered a new TPS65290 ZB Evaluation Module (old one is dead) to check if my use case work and it doesn't work. Maybe I remembered wrong when i said it work on my first EVM. With both boards i can't reach 5V with a VIN less than 4V. Also i notice that the Vout from the BB is 100-200mV higher than it should be (at the EVM), on my board it's <=100mV. Also i notice that the coil on the EVM is not the one listed in the BOM.

    EVM:

    VIN: 4V  VOUT: 5V (@R3 0x39), i can reduce VIN to 3,7V than the TPS goes "off", no short circuit

    My Board:

    VIN: 4V  VOUT: 5V (@R3 0x3B), i can reduce VIN to 1,8V than the TPS goes in "short circuit mode"

    It seems that the BB can only step up a difference <= 1V.

    It looks like the chip is still in beta phase?!?!

     

    Best regards
    Andreas