• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 2 answers
  • Subscribers 63 subscribers
  • Views 283 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LMG5200: optimization of VCC and PWM signals

Marcel Klose
Prodigy 80 points
Part Number: LMG5200
Other Parts Discussed in Thread: LM5163, TPS562231

Hello there,

we want to use LMG5200 for our Powersupply and made our own eval board with some issues.

I ran into that:

finding a solution here:

which was quite tricky. Please update the datasheet.

Anyway now the digital part is our problem.

I saw that you only use LDOs for 5V supply. Is this recommended? We use LM5163 from 60V down to 5V and see some really ugly stuff here. We already killed some LMG5200, probably bei <6V overshoots.

Furthermore I see 10pF to GND in the HI LI lines. Also some 10k pull downs and some 10R in series. Is this recomended too?

(all on the evalboards)

Information of our goal product:

60V Input

55V Output

5A Output

60V are also used to make 5V (LM5163). 5V are used to make 3.3V (TPS562231)

If I forgot something to mention please let me know

Best regards

Marcel

  • 0
    TI__Genius 16390 points

    Hello Marcel,

    Thank you for contacting us! The LMG5200 is designed to work with input voltage range of 4.75V to 5.25V. By having voltage lower than 4.75V will trigger UVLO and above the range could cause transistor gate breakdown. By using a buck converter for supplying 5V, the ripple content is likely to make the voltage range out of the specification. The easy way is to probe the output of the LM5163 to see if the voltage is within the allowable range. Normally, an LDO should be followed to make sure the voltage is stable.

    The 10pF of HI and LI is recommended for input signal filtering. 10k pull down resistor for PWM input is also recommended so that it avoids shorting the input to the ground.

    May I know what's the end application/equipment here?

    Regards,

  • 0 in reply to Yichi Zhang.
    Prodigy 80 points

    Hi Yichi,

    thanks a lot for the answer. That fit's to my observations. Anyway a more detailed datasheet in this points would be helpfull.

    The application is a very small high densitiy low ripple Powersupply for a research project.

    Anyway is there any information about the transient reaction? The LMG5200 seems to work with very low current, but it needs it really fast. Although we used more than enough Caps there seems to be some transients during switiching. Is this because of GaN technology, that you need less energy but you need it very fast?

    Best regards and thanks a lot for your efforts

    Marcel

  • 0 in reply to Marcel Klose
    TI__Genius 16390 points

    Hello Marcel,

    I don't know if I understand your question correctly here. Could you describe what transient behavior you observed here? As far as supplying power to GaN, there should not be special supply requirements here. You need to make sure the supply to the IC is stable (having LDO supply and bypass cap) and the bootstrap cap could hold up the charge for the high side FET power.

    Regards,