ETA1661

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7

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is again enabled. Depending on power dissipation, thermal resistance, and ambient temperature, the thermal

protection circuit may cycle on and off.

This cycling limits regulator dissipation, protecting the device from damage as a result of overheating.

OUTPUT VOLTAGE CONFIGURATION

In external Output Voltage Setting Version selected, the ETA1661 regulator is programmed using an

external resistor divider. The output voltage is calculated using below equation.

VOUT=VREF× (1+

R1

R2

)

Resistors R2 has to be between 1kOhm to 20KOhm and thus R1 is calculated by following equation.

R1=

�VOUTV

REF

-1

�×R2

PCB LAYOUT GUIDELINE

1

2

3

6

4

VIN

GND

SW

FB

BST

5 EN

ETA1661

Place as many vias as possible to

connect the Output Cap and GND

Place as many vias as possible to

connect the Input Cap and GND

R2

L

Cout

Cin

GND

VOUT

GND

GND

Capacitor should be

placed as closed to the

IC as possible

R2 between FB

and GND, it is the

lower resistor of

the voltage divider

to set the Vout ,

R2 has to be

connected to the

GND with

separated trace