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TPS628301: How to select inductors for TPS628301

Ryosuke Saigusa
Prodigy 10 points
Part Number: TPS628301

Tool/software:

I have a question regarding the inductor selection for the TPS628301.

According to the datasheet, the following information is given about the inductor:

  • Recommended Inductor: 0.24 to 1 µH (from section 6.3 Recommended Operating Conditions)

  • Inductor Calculation Formula: shown in the figure in section 8.2.2.3 Inductor Selection

For my application, the conditions are:

  • IOUT,MAX = 300 mA

  • ΔIL = 90 mA (IOUT,MAX × 30%)

  • fSW = 2 MHz (fixed)

  • VIN = 5 V

  • VOUT = 1.8 V

Based on these conditions, the calculated inductance value is about 6.4 µH.
However, section 6.3 (Recommended Operating Conditions) specifies a maximum of 1 µH, which is a large discrepancy compared to the theoretical value.

My questions:

  1. Is it acceptable to select an inductor greater than 1 µH (e.g., 6.4 µH) in this case?

  2. If I choose 1 µH, considering inductor tolerance (e.g., ±20%), the actual value may exceed 1 µH. Should I understand the “MAX 1 µH” in section 6.3 as excluding tolerance?

  • 0
    TI__Mastermind 25430 points

    Hello,

    Ryosuke Saigusa said:
    Is it acceptable to select an inductor greater than 1 µH (e.g., 6.4 µH) in this case?

    It is not recommended to use an inductor/capacitor beyond the datasheet specifications. 

    Ryosuke Saigusa said:
    If I choose 1 µH, considering inductor tolerance (e.g., ±20%), the actual value may exceed 1 µH. Should I understand the “MAX 1 µH” in section 6.3 as excluding tolerance?

    1uH is the nominal value. Inductor tolerance and current derating is anticipated. The effective inductance can vary by 20% and –30%.

    I hope this helps.

    Thanks,

    Febin

  • 0 in reply to Febin
    Prodigy 10 points

    Thank you for your reply.
    I understand, so I will close this case.