TPS746-Q1: TPS74612PQWDRVRQ1

Hi Tirthal,

What is the expected load for this supply? 3.3V -> 1.2V @ 1A is over 2W dissipated in the device, and there will likely be thermal issues if this supply is used at a large fraction of the rated current. 

My only other comment is that the orderable part number for this device is for the open-drain PG, which needs to be pulled up by a resistor in the range 10kΩ ~ 100kΩ. I see that the resistor is not populated, but for the BOM it should not be a 0Ω.

Regards,

Nick

Hi Nick ,

1. The Max Current from the LDO will be ~0.4A.

2. As per the datasheet it mentions 

" For the open-drain version, if the power-good functionality is not being used, ground this pin or leave floating"

So can you please provide clarity on this !

Regards,

Tirthal Patel

Hi Tirthal,

At 400mA there will still be 840mW dissipated in the device, which will equate to a junction temperature rise of approximately 67C if the PCB layout is similar to the JEDEC High-k board layout. If the max ambient temperature is less than 150C - 67C = 83C, this isn't an issue. 

Tirthal Patel said:

" For the open-drain version, if the power-good functionality is not being used, ground this pin or leave floating"

I understand that in this build/schematic implementation the resistor will not be populated, which leaves PG floating. What I meant is that if the pull up resistor does need to be populated in a future build, 0Ω is not an appropriate resistor value, and what I'm suggesting is to choose a resistor that would be in the correct range without needing to select a new resistor value in this case. 

Regards,

Nick

Hey Nick,

1. I missed on one main thing we are having 2 LDO in our design and (Each LDO would be delivering ~200mA .)

    So the combined Output from the 2 LDO is ~400mA.

2. Got your Point for the pullup for Open drain version, i.e if we are considering the to mount resistor Value should be in the range of  10kΩ ~ 100kΩ .

Hi Nick,

Thank you for the prompt response !

Regards,

Tirthal Patel