Tantalum Capacitors: For the legacy chip LP2981-N, tantalum capacitors are the best choice for use at the output of the LDO. Most good quality tantalums can be used with the LP2981-N, but check the manufacturer's data sheet to be sure the ESR is in range. At lower temperatures, as ESR increases, a capacitor with ESR, near the upper limit for stability at room temperature can cause instability. For very low temperature applications, output tantalum capacitors can be used in parallel configuration to prevent the ESR from going up too high.

Ceramic Capacitors: For the legacy chip LP2981-N, ceramic capacitors are not recommended for use at the output of the LDO. This is because the ESR of a ceramic can be low enough to go below the minimum stable value for the LP2981-N. A 2.2-μF ceramic was measured and found to have an ESR of about 15 mΩ, which is low enough to cause oscillations.If a ceramic capacitor is used on the output, a 1-Ω resistor is required be placed in series with the capacitor.

Aluminimum Capacitors: For the legacy chip LP2981-N, aluminum electrolytics are not typically used with the LDO, because of the large physical size. These aluminimum capacitors must meet the same ESR requirements over the operating temperature range, more difficult because of their steep increase at cold temperature. An aluminum electrolytic can exhibit an ESR increase of as much as 50x when going from 20°C to −40°C. Also, some aluminum electrolytics are not operational below −25°C because the electrolyte can freeze.