LN2_SAMPLE_US
interval = priv->power_nsamples[chan] * LN2_SAMPLE_US;
val = clamp_t(long, val, 1, (LN2_MAX_NSAMPLE * LN2_SAMPLE_US) / 1000);
val = DIV_ROUND_CLOSEST(val * 1000, LN2_SAMPLE_US);