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TPS74801: efficiency

Viktorija Cecil
Mastermind 18511 points

Part Number: TPS74801

Team, can you please confirm efficiency of the part in this design:

We are trying to use this part on two projects, but not clear on efficiency of the design.  I am assuming 83% per datasheet, can you verify. Please.

 

8.2.1.2 Detailed Design Procedure

First, determine what supplies to use for the input and bias rails. A 1.8-V input can be stepped down to 1.5 V at

1.5 A if an external bias is provided, because the maximum dropout voltage is 165 mV if VBIAS is at least 3.25 V

higher than VOUT. To achieve this voltage step, the bias rail is supplied by the 5-V supply. The approximation in

Equation 4 estimates the efficiency at 83.3%.

Can you please confirm?

Thanks!

Viktorija

  • 0
    TI__Guru 55940 points

    Hi Viktorija,

    For a linear regulator, efficiency calculations can be simplified to Vout/Vin when the output current is much larger than the ground current.

    Due to this, the efficiency of a linear regulator increases as you approach dropout.  With your 3.3 V input and 1.2 V output you will only achieve an efficiency of ~36%; however, if you decrease your headroom (Vin - Vout), you can achieve much higher efficiency.

    Very Respectfully,

    Ryan