TPS25751: TPS25751EVM + Bq25756EVM Power Path for PDO 1 PP1 and PP3 Source Issue

Tool/software:

Hi,

I'm using TPS25751EVM and Bq25756EVM togerher with considering the connection specified in the user guide. I succeed to work them properly for a single physical cell LFP 3.2V properly with selecting PP1 source for PDO1.

I made some of changes to be able to work them together properly:

1) Add external boost converter from battery to generate PP5V. This boost converter 800mA current limited. 

2) PP5V also used for "EXT_DRV" for the module BQ25756EVM.

3) "LDO_3V3" supply via J11 connector to BQ25756EVM SMBUS.

If I select PP1 source for PDO 1;

*Sink from charger 20V-15V-9V-5V at 3A without any problem. Battery goes into the charing.

*If I connect source I can get 5V/200mA or 5V/2.5A depending on the source and also 20V/3A it gives properly.

I dont want to use extra boost converter like 3.2V to 5V/3.6A since the size of the PCB is limited and cost issue. So I have tried to select which is specified PPHV source for PP3 for PDO 1.

At that moment sink is working properly but when I connect a source VBUS goes into hiccup mode and restart always.

At that moment;

*PP5V and LDO_3V still remain constant. When look at the VBUS, It behaves ON 5V and goes into the 0V again. It tries each second and goes into loop. I can not get any source if I connect other source like 20V/3A.

There might be clue for the find the reason, if I disconnect J11 ribon cable between BQ25756EVM and TPS25751EVM to be able to reach via BQSTudio to read registers, at that time if I connect source again the TPS25751 J3 connector can source successfully.

I believe in that the BQ25756EVM is working properly and I aleady tested on the bech standalone and it's working properly with full the voltage range as specified. I think there is a protection caused by the TPS25751 goes into the hiccup mode when I select PP3.

Could you please check the .json file? You may find the what am I missing?

{
  "questionnaire": {
    "device": "TPS25751",
    "toolBuildVersion": "1.1.0",
    "answers": [
      null, 0, 3, 3, 0, 0, 3, 0, 1, 1, 1, 3, 4, 3, 1.536, 15, 0.25, 1, 0
    ],
    "vendorId": "0000",
    "productId": "0000",
    "version": "1.0.0.2"
  },
  "configuration": {
    "data": {
      "selected_ace": [
        {
          "register": 6,
          "data": [0,0,0,0,0,0,0,0]
        },
        {
          "register": 22,
          "data": [0,0,0,0,0,0,0,0,0,0,3]
        },
        {
          "register": 40,
          "data": [2,1,63,75,0,0,0,0,0,0,0,0,0,0,0,0,1]
        },
        {
          "register": 41,
          "data": [210,0,128,0]
        },
        {
          "register": 50,
          "data": [
            5,170,42,44,
            145,
            49,
            32,
            44,
            225,
            2,
            0,
            44,
            177,
            4,
            0,
            44,
            177,
            148,
            237,
            44,
            65,
            54,
            32,
            0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
          ]
        },
        {
          "register": 51,
          "data": [
            4,44,145,1,16,44,209,2,0,44,177,4,0,44,65,54,
            0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
          ]
        },
        {
          "register": 55,
          "data": [118,192,18,65,144,145,33,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
        },
        {
          "register": 66,
          "data": [10,0,8,0]
        },
        {
          "register": 92,
          "data": [207,12,0,0,0,0,0,0,0,0,0,0,0,4,0,0,0,4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
        },
        {
          "register": 112,
          "data": [3]
        },
        {
          "register": 119,
          "data": [0,0,0,0,0,0,0,0,0,0,0,4,0,45,0]
        },
        {
          "register": 120,
          "data": [0,0,0,128]
        },
        {
          "register": 122,
          "data": [0,0,0,0]
        },
        {
          "register": 123,
          "data": [0,2,255,255,0,0,0,0,0,0,0,0,0,0,0,0]
        },
        {
          "register": 125,
          "data": [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
        },
        {
          "register": 126,
          "data": [0,0,0,0,0,0,0,0,0,0,0,0,0,0]
        },
        {
          "register": 152,
          "data": [0,0,0,0,0,0,0,0,0,0,0]
        }
      ]
    }
  }
}