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Axelite Confidential Materials, do not copy or distribute without written consent.

Rev.1.1 Nov.05, 2019

AX3984

Number Of Capacitors

MAX

CAP

ESR

ESR



△VESR = change in output voltage due to ESR

△IOUT = load transient.

ESRCAP = maximum ESR per capacitor (specified in manufacturer’s data sheet).

ESRMAX = maximum allowable ESR.

High frequency decoupling capacitors should be placed as close to the power pins of the load as

physically possible. For the decoupling requirements, please consult the capacitor manufacturers

for confirmation.

Output Voltage

The output voltage is set using the FB pin and a resistor divider connected to the output as shown

in the following AP Circuit. The output voltage (Vout) can be calculated according to the voltage of

the FB pin (VFB) and ratio of the feedback resistors by the following equation, where (VFB) is

0.925V:

)

R

R

(

R

V

V

2

1

2

out

FB







Thus the output voltage is:

2

2

1

out

R

)

R

R

(

925

.

0

V







External Bootstrap Diode

When the condition of Duty Cycle>65% occurs, it is strongly recommended to add an external

bootstrap diode (such as IN4148 or BAT54) between an external 5V and BST pin for efficiency

improvement.