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Original question:

DRV10987: Best cheapest solution for DRV10987 with I2C speed control?

DRV10987: DRV10987

Sadashiva Kamath
Expert 1135 points
Part Number: DRV10987

We're exploring possibility of connecting DRV10987's V3P3 to power-up other ICs with max. load current 5mA.

  1. What is IV3P3_MAX current of step-down regulator with resistor (linear mode)?
  2. What is switching frequency of 5-V Step-Down Regulator with 47uH inductor connected at SW pin (for ~5mA load current)?

  • 0
    TI__Mastermind 24405 points

    Hi Sadashiva,

    1. Maximum external load current for V3P3 LDO is 20 mA.

    2. The switching frequency of the regulator is not constant and changes with load. Measuring the current ripple frequency at 5mA load should give you the switching frequency at that load. 

    Regards,

    Vishnu

  • 0 in reply to Vishnu Balaraj
    Expert 1135 points

    Hi Vishnu,

    Can you please cross check answers to first question? Datasheet recommends 5mA (screenshot below) in linear mode. In my application, I need power supply/source of 3.3V@15mA to power Digital rheostat

     

    Question: What is IV3P3_MAX current of step-down regulator with resistor (linear mode)?  Answer. Maximum external load current for V3P3 LDO is 20 mA.

     

    As per datasheet, 

  • 0 in reply to Sadashiva Kamath
    TI__Mastermind 24405 points

    Your question was about IV3P3_MAX. IV3P3_MAX is the maximum load current from 3.3V LDO which is 20 mA. 

    The output voltage of Step down regulator in linear mode is 5V (typ). Maximum load current for this step down voltage regulator is 5 mA.

    Regards,

    Vishnu 

  • 0 in reply to Vishnu Balaraj
    Expert 1135 points

    I'm pasting question & answer again.

    Question: What is IV3P3_MAX current of step-down regulator with resistor (linear mode)?  Answer. Maximum external load current for V3P3 LDO is 20 mA.

    This is 5mA . right?

  • 0 in reply to Sadashiva Kamath
    TI__Mastermind 24405 points

    Sadashiva,

    Yes, you are right. Let me explain. DRV10987 has a step down regulator in linear and buck mode. Output voltage of this regulator is 5V. Also, this device has a 3.3V LDO and 1.8V LDO. Maximum load current of 3.3V LDO is 20 mA when the Step down regulator is in buck mode and 5mA when the Step down regulator is in linear mode. Since you mentioned you need power supply/source of 3.3V@15mA to power Digital rheostat, you may not be able to use the 3.3V LDO when step down regulator is in linear mode. 

    Regards,

    Vishnu