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A

9/03

DI-58

Table 1. Transformer Construction Information.

Figure 3. No-load Input Power Consumption.

Core

Bobbin

Winding Details

Winding Order

(pin numbers)

Inductance

Primary Resonant

Frequency

TRANSFORMER PARAMETERS

TDK PC40 EE13,

A

2

EE13 Horizontal 8 pin

Primary: 104T, 34 AWG

Shield: 12T, 2 x 30 AWG

Secondary: 15T, 30 AWG T.I.W.

Flux Band: 1T, 6 mm Cu foil

(T.I.W.: Triple Insulated Wire)

Secondary (5-6), tape, Shield

(3-4), tape, Primary

(4-1), tape, Flux band

(3-NC)

Primary: 1.36 mH ±10%, Leakage: 50 µH (max.)

300 kHz (minimum)

Figure 2. Load Regulation - CV/CC Characteristics

with Limits.

0.3

0.2

0.15

0.25

50

100

150

200

250

300

Input Voltage (VAC)

0

0.05

0.1

• To maintain the

±25% CC tolerance the primary inductance

tolerance should be tighter than

±10%.

• Minimize zero load consumption by reducing drain node

capacitance: Use double coated/grade 2 wire for primary

and do not vacuum impregnate. Avoid using an RC snubber

across the output diode.

• For resistive loads, increase C3 to 1

µF (electrolytic) to

allow adequate time for start-up at full load.

• For battery loads, an output LC filter is typically not

required but can be added for resistive loads to reduce

switching ripple.

• R1 can be replaced with an inductor for higher efficiency

(~10% increase).

• Adding a 1 mA to 2 mA pre-load reduces zero load voltage

by ~1 V but increases power consumption by ~10 mW.

• Diode D4 can be replaced with a Schottky for higher

efficiency.

• See AN-35 for more information.

10

6

8

0

0.1

0.3

0.4

Output Current (A)

0

2

4

0.2

V

V

Low Limit

High Limit