Func�on Descrip�on(Cont.)

noise of this circuit and improves efficiency. A ground

plane is recommended to connect input capacitor, output

capacitor, and GND pin of the FAC1507.

In the FAC1507 buck regulator circuit, the two major

power dissipating components are the FAC1507 and

output inductor. The total power dissipation of converter

circuit can be measured by input power minus output

power.

= V

IN

× I

IN

– V

O

× I

O

The power dissipation of inductor can be approximately

calculated by output current and DCR of inductor.

= I

O

inductor

× 1.1

The junction to ambient temperature can be got from

power dissipation in the FAC1507 and thermal impedance

from junction to ambient.

=(P

totalloss

–P

inductorloss

)× Θ

JA

The maximum junction temperature of FAC1507 is 145°C,

which limits the maximum load current capability. Please

see the thermal de-rating curves for the maximum load

current of the FAC1507 under different ambient

temperatures.

The thermal performance of the FAC1507 is trongly

affected by the PCB layout. Extra care should be taken

by users during the design process to nsure that the IC

will operate under the recommended environmental

conditions.

Several layout tips are listed below for the best electric

and thermal performance.

1. Do not use thermal relief connection to the VIN and

the GND pin. Pour a maximized copper area to the GND

pin and the VIN pin to help thermal dissipation.

2. Input capacitor should be connected to the VIN pin

and the GND pin as close as possible.

3. Make the current trace from VOUT pins to L to the

GND as short as possible.

4. Pour copper plane on all unused board area and

connect it to stable DC nodes, like VIN, GND, or VOUT.

5. Keep sensitive signal traces such as trace connecting

FB pin away from the VOUT pins.

3A 150KHZ PWM Buck DC/DC Converter

FAC1507

2019. 03. 27

14/15

Revision No : 1