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TPS65218D0: In the case of RSEL out of recommend range

Satoshi
Guru 19595 points
Part Number: TPS65218D0
Other Parts Discussed in Thread: TPS65218

Would you let me know the behavior of DCDC3 and DCDC4 when RSEL is outside the recommended range?

What kind of occur problems?

(For example, RSEL: 12.5kΩ~19.4kΩ)

【Background】
RSEL Resistor Accuracy: Assumes 5%.

The TPS65218B1 was within the recommended range with 5% accuracy.

For TPS65218D0, RSEL: 5% accuracy is outside the recommend range.

Best regards,

Satoshi

  • 0
    TI__Mastermind 20076 points

    Hi,

    If RSEL is outside of the recommended range it could lead to the incorrect output voltage set on DCDC3 or DCDC4. Are you seen an issue in your design with the output voltages?

    Thanks,

    Brenda

  • 0 in reply to Brenda Diaz
    Guru 19595 points

    Hi Brenda

    Thank you for reply,

    I haven't test the operation of Vout yet.

    One customer want to replace from TPS65218B1 to TPS65218D0 without changing the circuit as much as possible, and RSEL is 5% accuracy among them.

    They concerned that Vout will be incorrect if replace IC with RSEL: 5% accuracy.

    Or is there any documentation that described to use RSEL: 2% accuracy?

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Mastermind 20076 points

    We cannot guarantee the output voltage accuracy if the selected external components are not within spec. We recommend evaluating the RSEL resistor with the TPS65218D0 PMIC across the expected temperature range in a prototype board. If the worst case conditions in the application will result in a resistance variation beyond the spec limits, then a new resistor (ideally with the same footprint) must be selected. 

    Thanks,

    Brenda

  • 0 in reply to Brenda Diaz
    Guru 19595 points

    Hi Brenda

    I understood that resister need to change low variation.

    Would you let me know about two points below for background of change the RSEL range?

    ①What is the reason for change the RSEL range?

    　Is TPS65218 have any trouble for full RSEL range?

    　Are TPS65218 and TPS65218D0 differ the internal circuit on DCDC34_SEL?

    ②Why "change the RSEL range" is not described on below document?

    　（We are receiving complaints from one customer.）

    7128.TPS65218xx_Rev_history.pdf

     Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Mastermind 20076 points

    Hi,

    I checked this with the team internally and unfortunately the previous silicon revision TPS65218B1 is an obsolete device with limited information.

    The TPS65218D0 is the one with the new silicon revision. The RSEL spec values are based on simulation, validation and test results based on the new silicon revision to meet the performance specified in the data sheet.  

    Thanks,

    Brenda