EPR-21 datasheet(15/32 Pages) POWERINT

15 / 32 page

19-Nov-02

EPR-21 – 5 V, 30 W DC-DC Converter

voltage drop

VDB

0.7 Volts

Bias diode forward voltage drop

TRANSFORMER CORE SELECTION

Core Type

pr14x8

Core

PR14x8

P/N:

B65755-J-R87

Bobbin

PR14x8_Bo

P/N:

B65542-B-T1

0.253 cm^2

Core Effective Cross Sectional Area

2.53 cm

Core Effective Path Length

2000 nH/T^2

Ungapped Core Effective Inductance

4.4 mm

Bobbin Physical Winding Width

LG MAX

0.005

0.005 mm

Maximum actual gap when zero gap

specified

D FACTOR

1.00

Duty cycle factor

1.10

Transformer primary layers (split

primary recommended)

NMAIN

Main rounded turns

NS2

Vout2 rounded secondary turns (AC

stacked winding)

VOUT2 ACTUAL

0.0 Volts

Approximate Output2 voltage of with

NS2 = 0 turns (AC stacked secondary)

TRANSFORMER DESIGN PARAMETERS

Primary rounded turns

1449 Gauss

Max operating flux density at minimum

switching frequency

2794 Gauss

Max transient flux density at minimum

switching frequency

LP MIN

0.342 mHenries

Minimum primary magnetizing

inductance (assumes LG MAX-5um)

IMAG

0.151 Amps

Peak magnetizing current at minimum

input voltage

OD_P

0.38 mm

Primary wire outer diameter

AWG_P

27 AWG

Primary Wire Gauge (rounded to

maximum AWG value)

DUTY CYCLE VALUES

DUVON MIN

0.68

Duty cycle at minimum undervoltage

threshold

DVMIN

0.61

Duty cycle at minimum DC input

voltage

DVMAX

0.29

Duty cycle at maximum DC input

voltage

DOVOFF MAX

0.22

Duty cycle at maximum DC overvoltage

threshold

CURRENT WAVESHAPE PARAMETERS

1.835 Amps

Maximum peak primary current at

maximum DC input voltage

IPRMS

1.246 Amps

Maximum primary RMS current at

minimum DC input voltage

COUPLED INDUCTOR OUTPUT PARAMETERS

LMAIN

8.0 uHenries

Main / Output2 coupled output

inductance (referred to Main winding)

WLMAIN

144 uJoules

Main / Output2 coupled inductor full-

load stored energy

Page 15 of 32

Power Integrations, Inc.

Tel: +1 408 414 9660 Fax: +1 408 414 9760

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