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UCC28951-Q1: UCC28951-Q1

Rajashekar Koutla
Intellectual 590 points
Part Number: UCC28951-Q1

Hello

Can you explain how to set the delay or deadtime between the pulses given to the switches in each leg ? I didnot understand clearly, please explain .

If i want to keep the delay constant , Do i have to connect resistor divider and connect it to ADEL pin and ADELEF pin ?

Thanks !

  • 0
    TI__Mastermind 25570 points
    Hello Rajashekar

    You can set the fixed delays by choosing the resistors at the DELAB, DELCD and DELEF pins. You can defeat the adaptive delays function by tying the ADEL and ADELEF pins to GND.

    Regards
    Colin
  • 0 in reply to Colin Gillmor
    Intellectual 590 points
    Hello Colin

    1) Initially delay is set by resistors DELAB DELCD DELEF and given to the respective pins.Along with that , the resistor divider taken from Vref and given to the ADEL pin and ADELEF pin gives the adaptive delay. That resistor divider provides fixed voltage to ADEL pin and ADELEF pin if we connect it to the Vref. Am I right ??
    Then What is the use of connecting resistor divider to the Vref Since there is no control of delay time ? and Is there any difference of connecting that resistor divider taken from Vref and given to ADEL, ADELEF pin and if i connect simply ADEL and ADELEF pin directly to the ground.

    2) And if i connect the resistor divider taken from CS pin and connect it to the ADEL and ADELEF pin, whatever the voltage is available at ADEL and ADELEF pins , accordingly the delay time will change. Am I correct ? In this case, is there any control of delay time ?
  • 0 in reply to Rajashekar Koutla
    TI__Mastermind 25570 points

    Hello Rajashekar

    1/ You are correct - adding the potential divider to ADEL and ADELEF gives a fixed delay - the baseline delay is determined by the resistor at the DELAB, DELCD, DELEF and modified - by the voltage at ADEL and ADELEF. The modification is fixed, not adaptive. The resistors at the DELAB, DELCD and DELEF pins must be in the range 13k to 90k and one reason for putting a DC voltage on ADEL and ADELEF is to extend or modify the range of delay times which can be programmed by the resistor.

    2/ You are correct, tying ADEL and ADELEF to CS through a potential divider provides delay times which are a function of the votlage at the CS pin. The amount of variation is set by the KA factor as set by the potential divider ratio.

    Regards

    Colin