TLV62568A: PG pin sink current limit

Aadarsh G Krishnan

Part Number: TLV62568A

We are using TLV62568AP buck in one of our designs and the PG pin is used as enable to a load switch as shown below.

Can I connect the PG to EN directly or should I add R11 as shown? In the datasheet, it is given sink current of PG pin is 1mA max. While adding R11, I am getting other issues with the load switch.

over 1 year ago

0 Josef Marsmann over 1 year ago

TI__Expert 6510 points

Hi Aadarsh,

thanks for using E2E.

You can PG directly to the EN of the switch without R11.

Best regards,

Sepp

0 Aadarsh G Krishnan over 1 year ago in reply to Josef Marsmann

Prodigy 20 points

Thanks for the quick response. Just for clarification, in the datasheet it is given that PG pin is an open-drain output and is specified to sink up to 2 mA. Is this current limiting occurring internally, so we don't need to add any external resistors?

0 Josef Marsmann over 1 year ago in reply to Aadarsh G Krishnan

TI__Expert 6510 points

Hi Aadarsh,

For the PG open-drain output you always need a pull-up resistor. The value for the resistor have to be large enough that the current is below 2mA if the PG pin goes low. 127K in your design is ok

Best regards,

Sepp

0 Aadarsh G Krishnan over 1 year ago in reply to Josef Marsmann

Prodigy 20 points

Thanks for the response. Also, I have a capacitor C23, which will be charged to 1.8V and if we use 0E at R11, the charge stored in C23 need to sink through PG pin without any limiting resistors. If this 2mA limit is any RMS limit, then I think 1uF discharge current can go through R11 = 0E. What do you think?

0 Josef Marsmann over 1 year ago in reply to Aadarsh G Krishnan

TI__Expert 6510 points

Hi Aadarsh,

You are right. According the data sheet we have to limit the current to 2mA in all cases, so a R11 > 900Ω is needed to be on the safe side.

Best regards,

Sepp

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TLV62568A: PG pin sink current limit