AN2627

ST8R00 description

Doc ID 13913 Rev 2

5/19

Figure 3.

ST8R00W inductor current at light load

Figure 4.

ST8R00W inductor current at no load

For proper functioning of the device, only a few components are required: an inductor, two

capacitors and the resistor divider. The inductor chosen must not saturate at the operating

peak current. Its value should be selected taking into account that a large inductor value

reduces output voltage ripple, while a smaller inductor can be selected when it is important

to reduce package size and the total cost of the application. Finally, the ST8R00 family has

been designed to work properly with X5R or X7R SMD ceramic capacitors both at the input

and at the output. These types of capacitors, thanks to their very low series resistance

(ESR), minimize the output voltage ripple. Other low ESR capacitors can be used in

accordance with application requirements without compromising the correct functionality of

the device.

This device features an output current cut-off function. Two P-channel MOSFETs in a back-

to-back configuration, as shown in Figure 5, stop the output current when the inhibit is low

(Figure 6).

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