Hello Team,
We are trying to implement a circuit with the LM137H1PQMLV where we have a -5V in and we need a variable negative voltage between -4V to -1.2V. We currently selected the R2 as a variable pot of 500 ohms and R1 as 120 ohms per datasheet suggestions. Would you have any other suggestions? Cloud we just use higher values in the same proportion (I.E. 500K pot and 120K) for a higher impedance or do you see any issues with that?
Regards,
Renan
Hi Renan,
There may be some scenarios where the reference voltage does not reach -1.2V due to the influence of temperature and device-to-device manufacturing variability. Will this be an issue for the design, or is it ok if the voltage is able to be adjusted up to a max in the range of -1.3 to -1.2 V?
I would recommend not using high impedance values for your resistors. This device has a minimum load requirement, so you will need to make sure that you choose R1 and R2 so that the load is always high enough to meet this requirement. You could also use an added load to meet this requirement, but meeting the requirement using only the voltage divider resistors helps minimize the error that IADJ adds to the output voltage.
Thanks,
Sarah
