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Original question:

TPS65950 Charge Current Reading

TPS65950: TPS65950 Charge Current Reading

raunaq sinha
Prodigy 110 points
Part Number: TPS65950
Other Parts Discussed in Thread: DM3725, AM5706, AM5716

Hi,

We are using TPS65950 as part of DM3725 platform for one of our products

We are seeing an issue with few TPS65950 units. When we configure for software charging, where if we configure for 100mA charging current, we see current drawn is only 20mA. 

However when we read ADCIN10 and apply conversion formula, it tells it is drawing 80mA. Out of 500 units of TPS65950, we are seeing this issue with 15-20 units. We are not really sure, where is the issue here since this is happening with 15-20 units out of 500 units.

We can provide register configuration and conversion formula used.

Regards,

Raunaq Sinha

  • 0
    TI__Expert 8730 points
    Hi Raunaq,

    I have assigned your request to responsible Applications Engineer and we will get back to you as soon as possible.

    Regards,

    Murthy
  • 0 in reply to Krishnamurthy Hegde
    Prodigy 110 points
    Hi Murthy,

    Just wanted to clarify one doubt, as per TPS manual section section 9.4.7, If the current from the charger is less than 0.85 A in the battery charge mode, the slope used to adapt the
    MADC range is 0.88 mV/mA. For higher current, the slope is 0.44 mV/mA. When the current is 0, the
    voltage on ADCIN10 is 0.75 V. For the accessory charge mode, the ITOV system is the same, and the
    current is negative; therefore, the slope is also negative. The slope of ITOV block depends on the value of
    the BCICTL1 CGAIN bit. When the CGAIN bit is 0, the slope of 0.88 mV/mA is used, and when the
    CGAIN bit is 1, the slope of 0.44 mV/mA is used.

    So i was wondering if for a if charging current is 100mA, CGAIN value should be 0 or 1?

    Regards,
    Raunaq Sinha
  • 0 in reply to raunaq sinha
    TI__Genius 17380 points
    Hi Raunaq,

    In general for OMAP families devices (> 10 years old), we recommend upgrading to a more modern processor. The DM3725 recommends use of AM5716 or AM5706.

    I will try to assist but support for this device will be limited.

    Do you know which phase of charging are you in when observing this issue? You can hopefully determine this from Figure 7-2 or Figure 7-3 in the Technical Reference Manual. Once you have identified that, do you know which state from Figure 7-4 or 7-5 are you in? Based on Table 7-2, it looks like some of the states are automatic, have you confirmed that you are in a software-controlled state the entire time?

    Which registers are you setting to set the current limit?

    Lastly, have you looked into the battery charger interrupts (Section 7.6.3) to see if any of them are tripping?