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Designing for Very Fast Load Transients

PTH03050Y

PTH05050Y

PTH12050Y

SLTS221A–MARCH 2004–REVISED OCTOBER 2005

The transient response of the DC/DC converter has been characterized using a load transient with a di/dt of

1A/µs. The typical voltage deviation for this load transient is given in the data sheet specification table using the

optional value of output capacitance. As the di/dt of a transient is increased, the response of a converter's

regulation circuit ultimately depends on its output capacitor decoupling network. This is an inherent limitation with

any DC/DC converter once the speed of the transient exceeds its bandwidth capability. If the target application

specifies a higher di/dt or lower voltage deviation, the requirement can only be met with additional output

capacitor decoupling. In these cases special attention must be paid to the type, value and ESR of the capacitors

selected.

If the transient performance requirements exceed that specified in the data sheet, or the total amount of load

capacitance is above 3300 µF, the selection of output capacitors becomes more important.

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