TPS50601SPEVM-S: Purpose of the Schottky Diodes in the Reference Design

Hello Jerry,

The Schottky diode between PH to ground is to protect the FETs to avoid too much droop in the PHASE node below 0V. However, the diode is likely not required. With the newer version of the IC (TPS50601A-SP) I know the part has been verified to work without the diode. I will confirm that this is true of this part as well.

The Schottky diode between Boost and Vin is addressed in the following two E2E posts:
e2e.ti.com/.../339779
e2e.ti.com/.../612279

Hope that helps!

Thanks,
Kyle

Hello Kyle,

Thanks for the quick reply. Please confirm that the Schottky diode from PGND to PH is not needed for the TPS50601-SP.

I still need an answer to whether the Schottky diode from Vin to Boot is needed. The first E2E link you provided is no longer accessible. This thread may have been deleted. The second E2E link does not explain the purpose of the diode. It just explains that a bleeder resistor is needed if this diode is used.

Thanks,
Jerry

Hello Jerry,

I am working on confirming my first answer. Sorry, about that link, I'm not sure why it doesn't work. Here is what the answer said:

When operating with Vin = 5V Schottky diode between Vin and Boost pin is not required.
When operating with Vin = 3.3V Schottky diode between Vin and Boot pin is necessay. This is to ensure that Boot-phase UVLO does not impact the performance of EVM. Internal to IC there is a MoSFET and diode which has higher drop and can result in activaling BOOT-PH UVLO over process/ temperature. Thus using an external Schottky diode we can minimize the drop from Vin to Boot pin.
Datasheet electrcal table highlights BOOT-PH UVLO to be typically 2.2V and max 3V. Thus with exteranl schottky diode helps to ensure BOOT_PH UVLO is not triggered due to its lower fwd drop.

Thanks,
Kyle