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difference btw LM5104 and LM5106?

Other Parts Discussed in Thread: LM5106, LM5104

Hi All, 

Can someone explain what is the difference between the dead-time generated with LM5106 and LM5106?

Thank you

Leo

  • Hi Leo,

    The most important differences are: LM5104 integrated the boot strap diode; Enable function; Deadtime control;

    Other differences include ESD ratings, peak pull up current , .etc can be found by comparing the electrical tables.

    Br

  • Thank you Kening.

    I still don't fully understand the dead-time control though... I explain: it seems to me that both LM5104 and LM5106 have programmable dead time control. The only thing is that the LM5104 performs 'adaptive' dead-time control by measuring the gate voltage and only introducing the dead time after the gate voltage goes above/below the 50%, so this feature seems to be very safe to me as the device is actually measuring/comparing the gate voltage before closing the other switch. Does this happen with LM5106? It seem to me that LM5106 only generates a dead-time but does not measure/compare the gate voltage on the switches. So it is 'less safe' against shoot-through... Is my understanding correct?

    Thank you very much

    Leo
  • Hi Leo,

    The LM5104 intergrated the programmable deadtime time and the adaptive shoot-through circuitry. The adaptive circuit in the LM5104 monitors both LO and HO, and triggers a programmable delay generator after the LO/HO pin falls below threshold (≈ Vdd/2). So the total deadtime will have an additional part causing by propagation delay, The additional delay of the timer prevents lower and upper MOSFETs from conducting simultaneously, thereby preventing shoot-through. This feature is usefull for minimum the on time of freewheel diode and reduce the conduction loss. As you know, the effective dead-time range is 90ns to 200ns, it is much smaller than LM5106.

    While LM5106 didn't have the adaptive deadtime portion, so the deadtime is mainly determined by the deadtime timer which can be programmed by the RT resistor. But it don't mean it less safe, the dead-time of LM5106 can be adjusted from 100 ns to 600 ns. The wide dead-time programming range provides the flexibility to optimize drive signal timing for a wide range of MOSFETs and applications.

    Best Regards,
    Oliver
  • Hi Oliver,
    Thanks for the very exhaustive answer. I think I understand better now. So in regards to the dead-time difference btw LM5104 and LM5106, after your explanation it seems to me that basically the dead-time generated by LM5104 is the propagation delay (tp) + the delay set by the resistor RT (TRT) by looking at Fig. 17 in the datasheet for LM5104. In case of the LM5106 the dead-time generated is only TRT, configurable by changing the resistor RT value (fig. 19 in LM5106 datasheet).

    What I would like to confirm, is:
    in 8.2.3 the graph of FIg. 17 (for LM5104) shows the delay times named tHPLH and tLPLH. Are these times the total delay times (i.e. tp+TRT)?

    Thank you

    Kind Regards

    Leonardo
  • Hi Leonardo,

    tHPLH is the Upper output(HO) turn on propagation delay, and tLPLH is the Lower output(LO) turn on propagation delay, both of them are refer to the Input and including the deadtime set by the RT resistor, so there are the total delay times as you understand. Thanks!

    Best Regard,

    Oliver