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TPS2H000-Q1: Low Duty Cycle Behavior

Mark Malik
Prodigy 210 points
Part Number: TPS2H000-Q1

With respect to the TPS2H000 or similar 1000mR devices, what is the behavior of the device using PWM at low duty cycle?  Taking into account the slew rate of the output voltage and the delay on CS (B version)  and  /FAULT what is expected output of the device with the following conditions:

  • 250Hz PWM frequency
  • Duty cycle from 1% to 100% (40us to 4ms Ton)
  1. Are the turn on and turn off, rising time and fall time, somewhat symmetrical?  Can the parameters of off/on fall/rise be an the opposite end of the tolerance range?
  2. Given the minimum turn-on slew rate of 0.1V/us, the output voltage should a minimum of 4V, correct?
  3. What is the effect of the maximum tcs(on2) of 70us?  Figure 2 shows the start of tcs(on2) to be from the rising edge of Vinx.  What if there is also maximum td(on) and minimum slew rate?  What point should tcs(on2) start from?
  4. What if OUTx is commanded on into a short to Ground?  According to Section 8.3.3, the device will protect itself within 1us.  tcl(deg) is listed as a maximum of 180us.  Will the output be turned off and then sometime later a fault be indicated?

Thank you.

  • 0
    TI__Mastermind 26630 points

    Hello,

    1- Check figure 1 in the datasheet. it shows the Td(rise) and Td(fall) matching. The difference can be up to 60uS. 

    2- Not sure what you mean by minimum of 4V. slew rate is measured when VOUT changes from 10% to 90% (turnon) and 90% to 10% (turnoff)

    3- The tcs(on2) upper limit is 120uS and not 70uS. This limit includes td(on) and the slew rate. CS response to current in linear region (Vcs 0 to 4V) is fast.

    4- That is right. The deglitch time is the time the internal circuit takes to report the fault.

    Regards