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LM5175: High side driver behaviour

Clement MAGNIEN
Intellectual 390 points
Part Number: LM5175

Hi,

The LM5175 doesn't have charge pump, only boot strap to supply high side MOSFETs.

fig 12 in the datasheet, in Buck mode , SW2 is always high: how the high side MOSFET gate(HDRV2) could be supplied if SW2 doesn't go low to recharge the boot strap capacitor?(the datasheet says in 8.3.13:In buck operation, LDRV1 and HDRV1 are switched by the PWM controller while HDRV2 remains continuously on)

Same in boost mode.

Thanks,

Clement

  • 0
    TI__Guru* 78270 points

    Hi Clement,

    Thank you for considering the LM5175.  You seemed not yet tested the EVM.  Such issues have been taken care of by design.  Actually there is a proprietary circuit inside to keep the BOOT of the non-switching leg to be charged.  Don't worry, the high side FET of the non-switching leg will stay ON 100% duty in bypass during operation. 

    Thanks,

    Youhao Xi, Applications Engineering