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WEBENCH® Tools/TPS43060: TPS43060 external MOS driver high Qg MOS solution?

boer.deng
Expert 1085 points
Part Number: TPS43060

Tool/software: WEBENCH® Design Tools

Since the external MOS of the chip has higher requirements on Qg, and low Qg MOS is more expensive, the circuit is modified as shown in the schematic diagram.Meet the following questions:

1. Whether it is feasible to use the external driving voltage to drive the MOS tube;

2. Although the lower tube still USES totem pole, but the front drive is only 7.5v, will the MOS drive effect be bad?

3. If the upper tube is connected according to my method, whether the driving voltage is VCC_DRV? I see that your internal seems not to be complicated, and there is no clamp

4. At present, the output voltage of TPS43060 has been raised after plate-making, but the output voltage of HDRV is still a waveform without voltage boost. What's the matter with thisBoost+SR.pdf

  • 0 in reply to boer.deng
    TI__Guru* 78270 points

    Hi Boer,

    Thank you for considering the TPS43060.  I am not sure how you conclude that the TPS43060 is not able to directly drive your selected FET?  If you use external driver for the low side FET but the internal driver for the high side FET, you may defeat the dead time managed by the IC, and shoot-through may happen.  So, if you really want to use external driver, pay attention to dead time.

    Regarding your schematic:

    Firstly, your external VCC bias supply of ~11V (VCC_DRV) exceeds the BOOT-to-SW voltage rating and you may cause damage to the BOOT pin. 

    Secondly, the external driver and AGND are not used correctly.   Q5 collector should be at GND but not AGND, so is the VCC capacitor.  From your schematic, I cannot see how your AGND and GND are connected. There should have a single point connection on PCB.

    Please recheck your circuit, and attach some scope pictures to depict your concern/questions, and help us to fully understand the remaining issues.

    Thanks,

    Youhao Xi, Applications Engineering

  • 0 in reply to Youhao Xi
    TI__Guru* 78270 points

    Hi Boer,

    Can I close this thread by assuming the issue resolved, given no updates in the last few days?

    Thanks,

    Youhao