TPS51604: Dead time variation

Hi Sepeedah,

TPS51604 use adaptive dead-time control to minimize low-side body diode conduction time. This information is available on datasheet page 12. 

Due to variation of gate drive strength and gate capacitance of MOSFET, the dead time may vary part to part because it use adaptive control, not fixed dead time. 

Btw, this part has been released for many years and no customer report these is dead-time issue. 

Thanks

Qian

Thanks Qian. I understand the part supports adaptive dead-time, but we are needing something that lets the user set dead time, like UCC21520 using DT pin. But that part is overkill of course. Do we have anything similar to TPS51604 that lets the user set dead time?

Hi Sepeedah, 

Why does customer have to set dead time? The adaptive dead time scheme prevents short through. 

My product line does not have other part that dead time can be set externally. 

Thanks

Qian

Quin,

They are driving two coils, the dead time (phase shift) between the two creates a common mode voltage which in turn creates EMI issues. If they can predict this commode mode voltage, then they can take care of the EMI issue. Given the variable nature right now, it is hard to do that. Hence, asking if there is a solution that lets the user set a predefined dead time.

Hi Sepeedah, 

Understood. The work around solution is to add below circuit between DRVH/DRVL and MOSFET gate to set the dead time. 

Thanks Quin! That's very helpful. Right now the connection between DRVH/DRVL and MOSFET has a reverse schottky diode in parallel with a resistor. Therefore, we need to add the cap and the forward diode to the resistor branch, correct?

Is there a document that details the function of the circuit and how to appropriately size the components?