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TPS28225: TPS28225 operation with 3.3Vpwm derived directly from an MCU

KKF
Expert 4455 points
Part Number: TPS28225

Hi,

can you conform TPS28225 PWM pin (pin #3) can operate with a 3.3Vpwm peak at its PWM-pin (pin #3)?
The datasheet page 1 states PWM operation starting from 2V is supported but page 6 (Input PWM section) indicates a peak Vpwm > 4V (at TPS28225 pin 3) is needed.

Thanks and regards, KF. 

  • 0
    TI__Intellectual 2910 points

    KKF,

    Thank you for your interest in the TPS28225 gate driver. YES, the TPS28225 can operate with a 3.3Vpwm peak at its PWM-pin (pin 3).

    The max spec for falling threshold in the Electrical Characteristics Table (on pg 6), is based on an operating condition of VpwmPeak = 5V. The TPS28225 has a self-adjustable PWM 3-state input circuit. The input HIGH threshold is adjusted to about 75% of the input signal amplitude. In your proposed case of VpwmPeak = 3.3V, the HIGH threshold will adjust to approximately 3.3 x 0.75 = 2.475.

    Based on the values shown on the Electrical Characteristics Table for the condition of VpwmPeak = 5V, the equivalent threshold values for VpwmPeak = 3.3V operation would follow the table below. I just multiplied VpwmPeak by 70%, 75%, and 80%, respectively, for MIN, TYP, and MAX, value estimates.

    Parameter Test Condition MIN TYP MAX UNIT
    PWM 3-state falling threshold VPWM PEAK = 3.3 V 2.3 2.5 2.65 V

    You can learn more about the 3-state input circuit in section 7.3.4 of the data sheet.

    I hope this post answers your question. If it has, please press the "Verify Answer" buttton below.

    - Daniel