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TPS92692-Q1: PWM pin

Ivy Jin
Expert 4625 points
Part Number: TPS92692-Q1

Tool/software:

Hi team，

My customer uses 92692 in the constant current boost design, could you please give some comments for below question? Thanks.

The 5V LDO of Vref will be turned off when PWM is low? As shown in the picture below, the Vref is divided into PWM pin by KVL, the customer is guessing that there is a switching hysteresis. However, the premise is that the Vref will be turned off when the PWM is pulled down.

Is the customer's guess right? For the PIN10 in the figure, what is the purpose of such a connection?

The customer would like to achieve a low voltage non-start effect by adjusting the voltage on the PWM pin.

Regards,

Ivy

  • +1
    TI__Expert 5790 points

    Hi Ivy,

    The 5V LDO of Vref is a supply and can never and will never be turned off at any time.

    More information on PIN10 is provided in the datasheet on page 19:


    In this configuration, the PWM is initially being set by the voltage divider connected to VREF which is connected to PIN10. However, when the voltage provided to PIN10 exceeds 3V, the PWM dimming will be set to 100%. In our case the voltage divider connected to VREF initially sets the PWM dimming to 40% and when the 10V battery takes over, PWM dimming is set to 100%

    Regarding your last question:

    "The customer would like to achieve a low voltage non-start effect by adjusting the voltage on the PWM pin"

    I would appreciate it if you could rephrase it, as I do not believe I fully understand the question.

    Hope this helps!