STBB1-APUR Datasheet, PDF (15/22 Pages) STMicroelectronics – 1 A, high efficiency single inductor dual mode buck-boost DC-DC converter

STBB1-AXX
Application information
The minimum inductor value for the application is the higher between Equation 2 and
Equation 3. In addition to the inductance value the maximum current the inductor can
handle must be calculated in order to avoid saturation.
Equation 4
I_{PEAK −BUCK}
= (I_OUT
/ η) +
VOUT × (VIN_MAX − VOUT )
2 × VIN_MAX × fs × L
Equation 5
I_{PEAK −BOOST}
=
VOUT ×I_OUT
η × VIN_MIN
+
VIN_MIN × (VOUT − VIN_MIN )
2 × VOUT × fs × L
Where η is the estimated efficiency of STBB1-A. The maximum of the two values above
must be considered when selecting the inductor.
8.3
Input and output capacitor selection
It is recommended to use ceramic capacitors with low ESR as input and output capacitors in
order to filter any disturbance present in the input line and to obtain stable operation.
Minimum values of 10 µF for both capacitors are needed to achieve good behavior of the
device.
The input capacitor must be placed as close as possible to the device.
Doc ID 022197 Rev 2
15/22