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4E02N-Rev.P001

800KHz Synchronous Step-up

Converter with 5.5A Switches

EC3689

Output Capacitor

The output capacitor must completely supply the load during the charging phase of the inductor. A reasonable value

of the output capacitance depends on the speed of the load transients and the load current during the load change.

It is recommended to use X7R ceramic capacitors placed as close as possible to the VOUT and PGND pins of the

IC. A recommended output capacitance value is around 20~100µ F. Note that high capacitance ceramic capacitors

have a DC Bias effect, which will have a strong influence on the final effective capacitance. A 10 V rated 0805

capacitor with 10µ F can have an effective capacitance of less 5µF at an output voltage of 5V.

Layout consideration

Use wide and short traces for the main current path and for the power ground tracks. The input capacitor, output

capacitor, and the inductor should be placed as close as possible to the IC. Use a common ground node for power

ground and a different one for analog ground to minimize the effects of ground noise. Connect these ground nodes

at any place close to the ground pins of the IC.

Thermal information

Implementation of integrated circuits in low-profile and fine-pitch surface-mount packages typically requires special

attention to power dissipation. Many system-dependent issues such as thermal coupling, airflow, added heat sinks

and convection surfaces, and the presence of other heat-generating components affect the power-dissipation limits

of a given component.

Three basic approaches for enhancing thermal performance are listed below:

● Improving the power dissipation capability of the PCB design

● Improving the thermal coupling of the component to the PCB

● Introducing airflow in the system

SOP8(Exposed PAD) package it is about 1.96W. More power can be dissipated if the maximum ambient

temperature of the application is lower.