ISL8203M

FN8661 Rev 4.00

Page 13 of 18

May 12, 2016

reduces voltage ringing created by the switching current across

parasitic circuit elements. The ceramic capacitors should be

placed as closely as possible to the module pins. A minimum of

22µF ceramic capacitance for each channel is recommended.

A bulk input capacitance may also be needed if the input source

does not have enough output capacitance. A typical value of bulk

input capacitor is 100µF. In such conditions, this bulk input

capacitance can supply the current during output load transient

conditions.

Output Capacitor Selection

Ceramic capacitors are typically used as the output capacitors

for the ISL8203M. A minimum output capacitance of 2x22µF per

phase is recommended. Bulk output capacitors that have

adequately low Equivalent Series Resistance (ESR), such as low

ESR polymer capacitors or a low ESR tantalum capacitor, may

also be used in combination with the ceramic capacitors,

depending on the output voltage ripple and transient

requirements.

Thermal Consideration and Current Derating

from thermal modeling analysis, can be used as a guide for

thermal consideration for the module. The ISL8203M’s thermally

enhanced package offers typical junction to ambient thermal

(13°C/W with 200LFM airflow) with a typical 4-layer PCB board.

The derating curves (Figures 27 through 31) are derived from the

maximum power dissipation allowed, while maintaining the

junction temperature below a maximum junction temperature of

+120°C; the derating curves take into consideration the

increased power dissipation at elevated ambient temperatures.

The maximum +120°C junction temperature is recommended

for the module to load the current consistently and it provides the

5°C margin of safety from the rated junction temperature of

+125°C.

All the derating curves are obtained based on tests on the

ISL8203MEVAL2Z evaluation board (Refer to AN1941,

“ISL8203MEVAL2Z Evaluation Board User Guide”). If necessary,

the customer can adjust the margin of safety according to the

real application. In the actual application, other heat sources and

design margins should be considered.

Power Loss Curves

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