8

350 kHz x 200 mV

8 22.4 µF

3.3V

12V

3.3V

12V

¹

·

©

§

¹

·

©

§

8A x

x 1 -

8

21

LMZ12008

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SNVS716H – MARCH 2011 – REVISED FEBRUARY 2016

Product Folder Links: LMZ12008

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Copyright © 2011–2016, Texas Instruments Incorporated

The LMZ12008 module contains two internal ceramic input capacitors. Additional input capacitance is required

external to the module to handle the input ripple current of the application. The input capacitor can be several

capacitors in parallel. This input capacitance must be located in very close proximity to the module. Input

capacitor selection is generally directed to satisfy the input ripple current requirements rather than by

capacitance value. Input ripple current rating is dictated by Equation 12:

where

•

D

(12)

As a point of reference, the worst case ripple current will occur when the module is presented with full load

Recommended minimum input capacitance is 30-µF X7R (or X5R) ceramic with a voltage rating at least 25%

higher than the maximum applied input voltage for the application. TI also recommends to pay attention to the

voltage and temperature derating of the capacitor selected.

NOTE

Ripple current rating of ceramic capacitors may be missing from the capacitor data sheet

and you may have to contact the capacitor manufacturer for this parameter.

If the system design requires a certain minimum value of peak-to-peak input ripple voltage (

maintained then Equation 13 may be used.

(13)

If

(14)

Additional bulk capacitance with higher ESR may be required to damp any resonant effects of the input

capacitance and parasitic inductance of the incoming supply lines. The LMZ12008 typical applications schematic

and evaluation board include a 150-

μF 50-V aluminum capacitor for this function. There are many situations

where this capacitor is not necessary.