LT3468/LT3468-1/LT3468-2

9

sn346812 346812fs

Table 2. Pre-Designed Transformers - Typical Specifications Unless Otherwise Noted.

SIZE

LPRI-LEAKAGE

FOR USE WITH

TRANSFORMER NAME

(W × L × H) mm

(µH)

(nH)

N

(mΩ)(Ω)

VENDOR

LT3468/LT3468-2

SBL-5.6-1

5.6 × 8.5 × 4.0

10

200 Max

10.2

103

26

Kijima Musen

LT3468-1

SBL-5.6S-1

5.6 × 8.5 × 3.0

24

400 Max

10.2

305

55

Hong Kong Office

852-2489-8266 (ph)

kijimahk@netvigator.com (email)

LT3468

LDT565630T-001

5.8 × 5.8 × 3.0

6

200 Max

10.4

100 Max

10 Max

TDK

LT3468-1

LDT565630T-002

5.8 × 5.8 × 3.0

14.5

500 Max

10.2

240 Max 16.5 Max

Chicago Sales Office

LT3468-2

LDT565630T-003

5.8 × 5.8 × 3.0

10.5

550 Max

10.2

210 Max

14 Max

(847) 803-6100 (ph)

www.components.tdk.com

LT3468/LT3468-1

T-15-089

6.4 × 7.7 × 4.0

12

400 Max

10.2

211 Max

27 Max

Tokyo Coil Engineering

LT3468-1

T-15-083

8.0 × 8.9 × 2.0

20

500 Max

10.2

675 Max

35 Max

Japan Office

0426-56-6262 (ph)

www.tokyo-coil.co.jp

Capacitor Selection

For the input bypass capacitor, a high quality X5R or X7R

type should be used. Make sure the voltage capability of

the part is adequate.

Output Diode Selection

The rectifying diode(s) should be low capacitance type

with sufficient reverse voltage and forward current rat-

ings. The peak reverse voltage that the diode(s) will see is

approximately:

VV

N V

PK R

OUT

IN

()

•

The peak current of the diode is simply:

I

N

PK SEC

−

=

14

.

(LT3468)

I

N

PK SEC

−

=

10

.

(LT3468-2)

I

N

PK SEC

−

=

07

.

(LT3468-1)

recommended for most LT3468/LT3468-1/LT3468-2

applications. Another option is to use the BAV23S dual

silicon diodes. Toshiba makes a dual diode named 1SS306

which also meets all the requirements. The CRF02 is a

single diode with an 800V reverse voltage rating which is

also suitable. Table 3 shows the various diodes and

relevant specifications. Use the appropriate number of

diodes to achieve the necessary reverse breakdown volt-

age.

SW Pin Clamp Diode Selection

The diode D2 in Figure 6 is needed to clamp the SW node.

Due to the new control scheme of the LT3468/LT3468-1/

LT3468-2, the SW node may go below ground during a

switch cycle. The clamp diode prevents the SW node from

Table 3. Recommended Output Diodes

MAX REVERSE VOLTAGE

MAX FORWARD CONTINUOUS CURRENT

CAPACITANCE

PART

(V)

(mA)

(pF)

VENDOR

GSD2004S

2x300

225

5

Vishay

(Dual Diode)

(402) 563-6866

www.vishay.com

BAV23S

2x250

225

5

Philips Semiconductor

(Dual Diode)

(800) 234-7381

www.philips.com

1SS306

2x250

100

3

Toshiba

(Dual Diode)

(949) 455-2000

CRF02

1x800

500

Not Specified

www.semicon.toshiba.co.jp

APPLICATIO S I FOR ATIO