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Original question:

TPS54531: What is the maximum continuous output current

TPS54531: Request for Support – Noise and Short Issue in TPS54531 Circuit and Inductor also Heating

mahesh p
Prodigy 40 points

Part Number: TPS54531

Dear Sir & Madam,

As per your suggestion, I have drawn the schematic using the TPS54531 IC. I am facing the following issues during testing:

  1. When the input voltage is between 12 V and 13.8 V, noise is coming from the inductor. And Inductor also slightly Heating, However, when the input voltage increases above 14 V up to 27 V, the noise disappears.

  2. When I connect the load (a charging IC for 2-cell Li-Po Battery, 3.7V/2600mAh, Model 18650), a short occurs at the output side of the  Capacitor C65,C66 .

My input voltage range is 12–27 V, and the required output is 12 V / 4.5 A. and This my Inductor PartNumber ASPI-0630LR-100 

I have attached the schematic for your references.

Kindly review it and advise on possible causes and solutions for these issues.TPS54531-Power_supply.pdf 

Best regards,
P.Mahesh

  • 0
    TI__Genius 14090 points

    Hi Mahesh,

    We will check and get back on this.

    Regards,

    Haseen.

  • 0
    TI__Expert 4860 points

    Hello Mahesh

    I reviewed the schematics and here are the inputs:

    1. The inductor is rated only for 4A, and your current is 4.5A. So, the inductor will saturate at the load current and lead to noise, heating, losses and other such issues. 
    2. The value of the inductor is also not correct. For your input and output specs, you can go ahead with a 4.7uH-6.8uH inductance. I would recommend using 74437368047 from Wurth. You can find an equivalent too.
    3. Place a decoupling capacitor of 100nF, X7R, 0805 on the input pin very close to the IC. This will help in eliminating the noise too. It is a must to have a decoupling capacitor along with your bulk capacitors 
    4. The IC is limited to have a max. duty cycle of 91%, so the input voltage has to be above 13.5V to ensure 12V at the output. see section 8.2.2.11 in the datasheet
    5. Change C65 and C66 to 47uF, X5R or X7R, 35V capacitors. Use 1206 or 1210 package
    6. To design compensation components, refer to section 8.2.2.7 in the datasheet.
    7. Use 1% tolerance resistors for COMP and VSENSE pin 
    8. D4 is only rated for 3A, and the output current is 4.5A. Select a schottky diode with average forward current rating of minimum 5-6A and reverse voltage rating of 50V

    Regards

    Nikhil