What is the penalty for using an inductor with lower value than is recommended?
While lower-value inductors can be used with some success, there are three types of problems that may be encountered: • Higher inductor ripple current, so that the current limit is engaged at a lower-than-expected load current • Higher ripple voltage on the output, which may be seen as excessive noise by the load; • The possibility of pushing the crossover frequency above 40kHz, where the switching regulator becomes unstable. Inductor values recommended in the LM267X datasheets and in the associated design software (Switchers Made Simple, WEBENCH) are based on controlling the inductor ripple current, output ripple voltage, and frequency response to avoid these problems.
