Component selection

AN4397

14/19

DocID025515 Rev 1

4.3

Capacitance on MPP-REF pin

It's recommended to use C8 = 10 nF in most of the application cases.

4.3.1

Inductor selection

The SPV1050 device controls the switching of the integrated DC-DC by limiting the peak

current flowing through the inductor L1.

L1 = 22 µH covers the most typical application range: the lower is the series resistance of

the selected inductor, the lower is its DC loss. The current capability of the selected inductor

must be ≥ 200 mA.

4.3.2

Output voltage ripple

In case of battery with high series resistance and fast load transient, the capacitor on the

threshold, implying the battery disconnection.

Although the fast transient might be masked by a proper capacitance between UVP and

GND pins, if the battery has low peak current capability, the voltage on the STORE pin may

Increasing the capacitance on the STORE pin has the drawback of affecting the output time

constant and consequently delays the startup time. The same capacitor might be placed in

parallel to the battery.

The selection of the battery and of the output capacitance on the STORE pin (C9) is strictly

related to the following application parameters:











The maximum current that can be supplied to the load is the sum of the currents that can be

Equation 7

The maximum current that the battery can supply without triggering the UVP threshold is:

Equation 8

The amount of charge that the C9 can supply is:

Equation 9

Q9 = C9



–

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=