The resistor values that determine Vout, R1 and R2, are shown in table 3 of the datasheet.
They are an order of magnitude smaller than other part numbers, but is there any particular reason for this? Is it okay to use a value 10 times larger without changing the ratio?
Are there any drawbacks to multiplying the value by 10?
Hi Ken,
For the MPM3683-10, the relatively small R1/R2 values in Table 3 are intentional. This device uses a constant-on-time control scheme, and lower feedback resistor values keep the FB node impedance low, which improves noise immunity and stability, especially in the presence of fast switching edges.
Although keeping the same ratio and increasing both resistors by 10× may still regulate the output voltage, it is not generally recommended. Higher resistor values make the FB node more susceptible to noise, increase sensitivity to FB bias/leakage currents, and change the effective compensation since the R–C time constants (with CFF) also scale.
In practice, it is best to follow the datasheet-recommended values. If larger resistors are used, CFF and loop behavior should be re-evaluated and verified for stability. But I think for most of the conditions, there will be no problem if you want to use 10x resistors.
Best,
Fox
Hi Fox,
Thank you for your reply. I will take this into consideration.