R1191x

7

TECHNICAL NOTES

When using these ICs, consider the following points:

In these ICs, phase compensation is made for securing stable operation even if the load current is varied. For

this purpose, use a capacitor C2 with good frequency characteristics and ESR (Equivalent Series Resistance).

(Note: If additional ceramic capacitors are connected with parallel to the output pin with an output capacitor for

phase compensation, the operation might be unstable. Because of this, test these ICs with as same external

components as ones to be used on the PCB.)

Connect a capacitor C1 with a capacitance value as much as 2.2

close as possible to the pins.

Set external components, especially the capacitor C2, as close as possible to the ICs, and make wiring as

short as possible.

There is the built-in thermal-shutdown function in R1191x series. It discontinues operation of the IC when the

junction temperature becomes over 150

°C (Typ.) and IC re-operates when the junction temperature under

130

°C (Typ.). If the temperature increasing keeps the IC repeats ON and OFF operating. The output becomes

the pulse condition.

To maintain the stability of the output voltage, please do not use the intermediate electric potentials (the

potentials increases the supply current and causes the unstable output voltage.

R1191xxxxD has adopted Auto-discharge function, which decreases the output voltage quickly to 0V by

electrical charges accumulated in the external capacitor.