• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 64 subscribers
  • Views 195 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.

LM2574: LM2574M-3.3

Davide Italia
Prodigy 70 points
Part Number: LM2574

Dear Team,

I use the LM2574M-ADJ,with a resistive divider, to generate a +5.0V.

Due to the limited availability of the component LM2574M-ADJ,  can I use the LM2574M-3.3 to generate a +5V inserting a series resistor 1k43 between the pin 1(feedback) and Vout (+5V)(voltage output of circuit) (1.23V/1k*(1k+1k7+1k43)=+5.08V) ?

Which tolerance on output voltage can I expect ?

The LM2574M-3.3 has an internal resistor divider network R2=1k7, R1=1k0 that is applied to the non−inverting input of the internal error amplifier.  Which is the tollerance of R2 and R1 ?

Best Regards

Davide

  • 0
    TI__Guru 65515 points

    Hello

    Although it is theoretically possible to use an external resistor as you propose, the accuracy will be very poor.

    The absolute values of the internal divider resistors will have a tolerance of up to +/-30%; although the resistor matching is very good.

    Furthermore, the temperature coefficient of the internal resistors will be different from your external resistor, adding more error to you output voltage.

    One possibility is to use an external voltage divider.  The absolute values of these resistors would need to be much less than the absolute values

    of the internal resistors.  This is because you don't want the internal divider to load your external divider and cause errors. 

    In this case, since the internal resistors are rather small, you would need to use external resistors that may be too small to be practical.

    You may want to look at the LM2594-5 or the LM2674-ADJ.   They seem to be in stock.

    Thanks