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LM5106: Delay between setting input and enable signal

bhaktha Keshavachar
Intellectual 450 points
Part Number: LM5106

Hello,

We are seeing issues in enabling the LM5106 MOSFET driver chip. Not sure what is going wrong. Got a doubt though ...

This is the sequence of instruction we have for setting the input and enabling the driver in our AHB circuit

GpioDataRegs.GPACLEAR.bit.GPIO0 = 1; // IN of one arm of the AHB
GpioDataRegs.GPACLEAR.bit.GPIO1 = 1; // IN of the other arm of the AHB

// Need delay here ?

GpioDataRegs.GPBSET.bit.GPIO58 = 1; // Enable of the first arm of the AHB
GpioDataRegs.GPBSET.bit.GPIO59 = 1; // Enable of the other arm  of the AHB

The processor that is driving the LM 5106 is running at 200 Mhz, so the delay between setting the input and setting the enable is about 5 nS. Is that too "fast" ? Do we need a delay between the setting the input and enabling the driver ? The various propagation delays of the 5106 are much higher than 5 nS.

Appreciate any pointers.

Thanks. -Bhaktha

  • 0
    TI__Genius 13445 points

    Hello Bhaktha,

    Thanks for reaching out.

    The IC can be operated with a PWM signal on IN pin and using the EN pin to disable the driver in standby mode by pulling the output pins (HO and LO) low.

    I have reviewed the datasheet and there is no specific requirement to delay IN and EN signals. With a 100kOhms deadtime resistor, you should expect prop delay values specified in section 6.6 of the datasheet therefore can you please share where the 5ns prop delay requirement is coming from and which prop delays that is referring to? IN to LO/HO? EN to LO/HO?

    Can you also confirm your switching frequency? I ask because depending on load, gate drive voltage, I have serious concerns about the IC operating a 200MHz switching frequency.  

    If available, can you please share your schematic and what exactly you're trying to accomplish?  

    Regards,

    -Mamadou

  • 0 in reply to Mamadou Diallo
    Intellectual 450 points

    Mamadou,

    Thanks for your response over the weekend. Much appreciated. The problem we were seeing had some other root cause. We fixed that and got over that hurdle.

    Thanks. -Bhaktha