• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 129 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.

LM2991: Output Voltage

user4638730
Prodigy 100 points
Part Number: LM2991

Hi,

I am using LM2991 with Vin = -5V, Vout = -2V, Iout = 0.3Amax now.

However, to fix the problem, I need to use the LM2991 Vout at -1.55V.

When I refer to the data sheet, Vout is typ -2V, but there is no value for min.

Since Vref = -1.21V, I think it is possible to output Vout = -1.55V, is that correct?

I think of R2=750ohm and R1 = 2.7kohm. And my circuit current is 40mA min, so minimum load is no problem.

Regards,

Ikuo

  • 0
    TI__Mastermind 33665 points

    Hello Ikuo,

    There is nothing obvious in the datasheet which indicates to me that you cannot use this device down to the reference voltage for the output voltage.  It appears that -1.55V would be fine given your conditions.  Still, datasheets back as far as 1994 listed this -2V minimum in their datasheets.  You may want to test this to confirm that you can achieve -1.55V. 

    Thanks,

    - Stephen

  • +1
    Prodigy 100 points

    Hello Stephen-san,

    Thank you for your reply.
    I will confirm and use it as you recommend.

    Regards,

    Ikuo