TPS543820: Enable pin control

Jilu John

Part Number: TPS543820

Tool/software:

Can we connect an external power supply of 3.3V to the enable pin of the IC TPS543820 directly, with a default a PD of 4.7K on the enable pin ?
As shown below.

6 months ago

0 David_Daniels 6 months ago

TI__Mastermind 23975 points

Jilu John,

The abs max voltage rating for the EN pins is 6V.

Connecting a 3.3V power supply with the 4.7kohm pull down is okay.

The EN pin has an internal pull up current source.

David

0 Jilu John 6 months ago in reply to David_Daniels

Prodigy 20 points

Hi David,

Thanks for the quick reply.

Since the PU current source value is not mentioned in the data sheet, could you confirm the current source will not impact my 3.3V supply ?

Does the PU (current source) work in such a way that, if the enable pin voltage is not enough to meet the 1.2V threshold, the current source will be active to enable the buck ?

0 David_Daniels 6 months ago in reply to Jilu John

TI__Mastermind 23975 points

When the enable pin voltage is below the start threshold the pullup current is 1.5uA typical. When the enable pin voltage is greater than the start threshold and additional current is added. The additional current provides hystersis between the start and stop voltage when the adjust vin uvlo resistor network is added see figure 7-2 on https://www.ti.com/lit/ds/symlink/tps543820.pdf#page=11 and equations 1 and 2.