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Original question:

CC1352P: Inductor Selection

CC1352R: CC1352R Inductor Selection

Fabian Schorrer
Prodigy 10 points

Part Number: CC1352R

Hi, 

we are working on a design with the CC1352R and we are using the internal DCDC Converter. 

Between DCDC_SW and VDDR_RF an inductor is required. What are the electrical requirements of the inductance?

I know that the technical documentation referes to the reference design with the MLZ2012N6R8LT000, but due to space limitation we can only use smaller ones. Also in case of second source issues, there is a need for gerneral requirements to the Inductance. 

In the technical reference manual there are information that allows conclusions to be drawn about certain parameters.
in Table 11-4:

  • inductor current: 46mA to 87mA? 
  • "Assuming 10µH external inductor!" --> 6,8µH or 10µH?

or in Table 7-10

  • DCDC clock source 48MHz --> On which switching Frequency is the DCDC running? 

best regards 
Fabian

  • 0
    TI__Mastermind 34790 points

    Hi,

    For CC13xx the inductance should be 6.8 uH. 

    The larger size has the advantage of a lower DC reistance:

    0805 MLZ2012N6R8LT000 has 0.25 ohm DC resistance

    0603 MLZ1608M6R8WT000 has 0.74 ohm DC resistance

    Using a smaller size such as 0402 will have a few ohms resistance. Every ohm increase of the DC resistance will increase the current consumption for all modes by approx 1 percent.

    Recommend to 0603 MLZ1608M6R8WT000  if 0805 is too large.

  • 0 in reply to RGW
    Prodigy 10 points

    Hi RGW, 

    the fact with the dc resistance of course makes sense.
    We have also preferred the MLZ1608M6R8WT000 so far.

    For a better second souce selection:

    • Are there more requirements for the Inductance? 
    • max. inductor current needed? 
    • At which switching Frequency is the DCDC running?

    best regards
    Fabian

  • +1 in reply to Fabian Schorrer
    TI__Mastermind 34790 points

    Hi,

    - Saturation current should be > 80 mA

    - Current rating should be > 300 mA

    - Component value tolerance: +/- 20 %

    - DC resistance < 0.8 ohm