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LM5106: Several questions

Hirotaka Matsumoto
Guru 27585 points
Part Number: LM5106
Other Parts Discussed in Thread: UCC21520, UCC27222, UCC20520, UCC21220, UCC21222

Hi all

Would you mind if we ask LM5106?

<Question1>
On the datasheet Figure 19. Dead-Time vs RT Resistor Value, it shows the relevance between DEAD-TIME and RDT(kohm)(10kohm upto 150).
Is it possible to use the resistor with the range 0kohm upto 5kohm?

<Question2>
In relation to <Question1>, when the resistor is the range 0kohm upto 5kohm, does dead time decrease linearly?
Or if you have the figure Figure 19. Dead-Time vs RT Resistor Value in case of 0kohm upto 5kohm, could you share us it?

<Question3>
In relation to <Question2>, when the resistor is the range 0kohm upto 5kohm, how much is the tolerance of DEAD-TIME?
Concretely, our customer assumes that they will use RDT=1.5kΩ,
In case of RDT=100kΩ, there is the description that MDT is 50ns.

<Question4>
Could you give us the figure which is "Dead-Time vs Temperature" like as Figure15 and Figure16 in case of RDT=0kohm ～ 5kohm ?
Or, in case of RDT=0kohm ～ 5kohm, which is the tendency similar with Figure15 or Figure16?

Kind regards,

Hirotaka Matsumoto

  • 0
    TI__Genius 12990 points

    Hi Hirotaka,

    Thanks for asking about LM5106. I am an apps engineer and will help you out.

    Figure 19 shows that the deadtime can be adjusted from 100ns to 800ns with a resistor value from 10k to 150k. A resistor value of 5k on RDT can be used however since there is no minimum spec past 86ns @ 10k we do not recommend operating the deadtime less than ~100ns when using LM5106.

    What application is this for? And what is the deadtime that is needed?

    We have a variety of parts with various deadtime settings, I made a table to summarize most of them. If you require 50ns DT then UCC27222 and isolated gate driver UCC21520 as well as other isolated gate drivers featuring a similar DT setting.

    Thanks,

  • 0 in reply to Jeffrey Mueller
    Guru 27585 points

    Jeff san

    Thank you so much for your reply!

    What application is this for? And what is the deadtime that is needed?
    ->The application are robot arms. We confirm the deadtime that is needed from the customer.

    Kind regards,

    Hirotaka Matsumoto

  • 0 in reply to Hirotaka Matsumoto
    TI__Genius 12990 points
    Hi Hirotaka san,

    Thanks for your update,

    From what I understand you want ~50ns deadtime but the tolerance needs to be predictable across temperature?
    In the mean time of confirming deadtime, can you tell me more about the driver thats needed to power the motors for the robot arms?
    what FETs are used? what VDD for the driver is needed? is isolation required? what is the bus voltage and power?

    Thanks,
  • 0 in reply to Jeffrey Mueller
    Guru 27585 points

    Jeffrey san

    Thank you for your reply!

    From what I understand you want ~50ns deadtime but the tolerance needs to be predictable across temperature?
    In the mean time of confirming deadtime, can you tell me more about the driver thats needed to power the motors for the robot arms?
    ->We are checking whether the customer needs ~50ns deadtime or not.

    what FETs are used?
    ->It is difficult to get this information.

    what VDD for the driver is needed?
    ->We assume that VDD is less than 16V.

    is isolation required?
    ->Bus voltage is 48V, so isolation is not reguired.

    what is the bus voltage and power?
    ->DC48V.

    The costomer application contains many confidential things.
    We are sorry that it is difficult to get some information.
    We will update you after we get some information.

    Kind regards,

    Hirotaka Matsumoto 

  • 0 in reply to Hirotaka Matsumoto
    Guru 27585 points

    Jeffrey san

    Thank you for your reply!

    FYI, we have update information as follows;

    <Request of dead time>
    -30ns~50ns

    <Request of ABS Vbus>
    Worling : 56V
    ABS min 70V, ABS max 100V

    Kind regards,

    Hirotaka Matsumoto

  • 0 in reply to Hirotaka Matsumoto
    TI__Genius 12990 points
    Hi Hirotaka san,

    Thanks! I believe we will need to use an isolated gate driver for this. Below is a list of all the gate drivers we have capable of 30-50ns deadtime and a 100V bus. All these drivers feature programmable deadtime and can achieve 30-50ns with a 3-5kohm Rdt resistor by using the equation DT(ns)=10*Rdt from the datasheet.

    Programmable DT isolated drivers:
    UCC20225x
    UCC20520
    UCC21220
    UCC21222
    UCC21520x
    UCC21521x

    Please let me know if this does not help you find the driver you need.
    Thanks,