Hello,
I am using LP2980AIM5-5.0/NOPB to supply one INA330, one OPA2350 and one REF3312 for a thermistor exciting and conditioning circuit.
Input voltage is 12V and total output current is nearly 30mA.
I am having an issue with the output capacitor. I am currently thinking of using a 10uf tantalum (TAJB106K016RNJ) in the output, whose ESR is 2.8 ohms max @ 100kHz.
However, very close to it, there is the OPA2350, for which, quoted from the dsheet: "Power supply pins should be bypassed with 0.01μF ceramic capacitors." For all effects, I am considering this ceramic cap as if an output cap for LP2980.
In another PCB, referring now to another circuit, I am also using LP2980AIM5-5.0/NOPB to supply power to ADS8320, and it also requires 0.1uF close to Vref, which I was also considering using ceramic.
From the 0805YA103JAT2A (0.01uF) and 08055C104MAT2A (0.1uF) capacitors dsheets, we get that the lowest ESR values is for 0.1uF, around 0.06 ohms.
That seems not far from the 0.015 ohm min value found in fig. 36 in LP2980 dsheet, for 10uF.
Truth is that if I can't bypass power supply of IC's that are being powered by LP2980, it gets useless!!
What are your thoughts about using both those 0.1uF and 0.01uF ceramic bypassing components that is physically located very close to the LP2980 output?
Also, if I increase output tantalum capacitance (maybe 47uF, just a guess), would it make LP2980 more stable for those ceramic caps??
Thank you!
