TPS74801: Add a 2.2 Ohm to 5V on bias pin

Ryan Yang4

Prodigy 100 points

Part Number: TPS74801

Hi, team

My customer have a application like the picture below, which add a 2.2 ohm resistor pull up to 5V.

Does this have a concern ?

From the datasheet, " BIAS pin current's " current limit is 2mA.

Does this resistor should be at least 5.1k ohm to fit the Bias pin current?

over 6 years ago

0 Ryan Eslinger over 6 years ago

TI__Guru 55940 points

Hi Ryan,

The BIAS rail is used to power the internal blocks of the TPS748 and could be tied directly to the 5 V rail if desired. The Ibias specification in the Electrical Characteristics table is showing that the internal circuitry will require a maximum of 2 mA for operation. As such, when you calculate the current budget for your 5 V rail, you should reserve 2 mA for the TPS74801.

Very Respectfully,
Ryan

0 Ryan Yang4 over 6 years ago in reply to Ryan Eslinger

TI__Prodigy 100 points

How many watts does this resistor have to withstand?

0 Ryan Eslinger over 6 years ago in reply to Ryan Yang4

TI__Guru 55940 points

Hi Ryan,

The maximum current that will flow through this resistor is 2 mA.

P = I^2 x R
P = (2 mA)^2 x 2.2 Ohm
P = 8.8 uW

Very Respectfully,
Ryan

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TPS74801: Add a 2.2 Ohm to 5V on bias pin