Automotive general-purpose LDO regulator series offering a total of 43 modelsA Simple LDO with No Shortcuts When It Comes to Power Saving and Miniaturization

－ With regard to automotive use, what other features does the LDO series offer?

It goes without saying that for automotive equipment, power saving and miniaturization are critical requirements. Since automotive power supplies are battery powered, power consumption should be as low as possible. For LDO ICs, key points are how much self-current consumption can be reduced and what extent miniaturized external components can be used.

－ Well, first of all, tell us about power saving.

In the LDO series, we have succeeded in cutting no-load supply current consumption to one-half or less when compared with conventional products.

－ The graph shows a power consumption characteristic radically different from conventional products, does it not?

In a conventional product, the current consumption by itself (circuit current) increases as the load current increases. A vast majority of LDOs has this property. Improving on this property, in this series there is little increase in current consumption even when load current increases. This factor can reduce the amount of heat dissipation, supply more load current, and increase the margin of tolerance with respect to temperature.

－ Pardon me for asking a basic question, but do you mean that there are LDO ICs in which ceramic capacitors cannot be used as output capacitors?

The LDO performs regulation by means of a feedback loop from the output. However, the output capacitance and the output impedance create a pole, with the result that reduction in phase margin can induce oscillation. There are several approaches to maintaining stability. In most cases, the technique of adding a zero point by using ESR of the output capacitor is employed. Therefore, since the output capacitor must have an appropriate ESR, as a rule aluminum electrolyte capacitors are used. On the other hand, ceramic capacitors, with low ESR values, tend to produce unregulated output. If a ceramic capacitor must be used despite this fact, resistors equivalent to the required ESR must be added at the expense of an increased number of components as well as a larger footprint.

－ Does that mean that aluminum electrolytic capacitors will not work?

Most of aluminum electrolyte capacitors have a through-hole form-factor. Consequently, in terms of size reduction, the aluminum electrolyte capacitor does not fare well in area and height aspects. Aside from the issue of size, ceramic capacitors have a longer lifetime than aluminum electrolyte capacitors, and represent a better choice for devices for which longevity is of paramount importance.

－ By the way, can electrolytic capacitors also be used in the LDO series?

Yes, of course, as long as the LDOs are selected with careful consideration of space, cost, and durability.

－ As a final point, could you wrap it up?