LTC3441 Просмотр технического описания (PDF) - Linear Technology

Номер в каталоге

Компоненты Описание

производитель

LTC3441

Photoflash Capacitor Chargers with Automatic Refresh

Linear Technology 

LT3420/LT3420-1

APPLICATIO S I FOR ATIO

efficiency of the circuit. In addition, the effective capaci-

tance on the primary is largely dominated by the actual

secondary capacitance. This is simply a result of any

secondary capacitance being multiplied by N2 when re-

flected to the primary. Since N is generally 10 or higher, a

small capacitance of 10pF on the secondary is 100 times

larger, or 1.0nF, on the primary. This capacitance forms a

resonant circuit with the primary leakage inductance of the

transformer. As such, both the primary leakage induc-

tance and secondary side capacitance should be mini-

mized.

Table 2 shows various predesigned transformers along

with relevant parameters. Contact the individual trans-

former manufacturer for additional information or

customization.

Table 2a. Predesigned Transformers, LT3420

PART

TURNS L

SIZE

RATIO (µH) LxWxH (mm) VENDOR

SRW10EPC 1:12 24 10.9x10.8x5.2 TDK

-U01H003

(847) 803-6100

www.components.tdk.com

6375-T108 1:12 15 10.8x9.5x3.6 Sumida

(847) 956-0666

www.sumida.com

PA0367

1:12 24 9.1x9.1x5.1 Pulse

(858) 674-8100

www.pulseeng.com

SBL-6.4

1:12 17.5 10.3x6.4x5.2 Kijima Musen

852-2489-8266

kijimahk@netvigator.com

Table 2b. Predesigned Transformers, LT3420-1

PART

TURNS L

SIZE

RATIO (µH) LxWxH (mm) VENDOR

SBL-5.6S-2 1:10 15 5.6x8.5x3.0 Kijima Musen

852-2489-8266

kijimahk@netvigator.com

LDT565630T 1:10.2 14.5 5.8x5.8x3.0 TDK

-002

(847) 803-6100

www.components.tdk.com

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:

VPK-R ≈ (VOUT + (N • VBAT)) • 1.65

The peak current of the diode is simply:

IPK-SEC

=

1.4A

N

(LT3420)

IPK-SEC

=

1.0A

N

(LT3420 − 1)

For the circuit of Figure 1 with VBAT of 3.3V, VPK-R is 590V

and IPK-SEC is 116mA. Table 3 shows various diodes that

can work with the LT3420/LT3420-1. These are chosen for

low capacitance and high reverse blocking voltage. Use

the appropriate number of diodes to achieve the necessary

reverse breakdown voltage.

Table 3

PART

MAX REVERSE CAPACITANCE

VOLTAGE (V)

(pF)

VENDOR

GSD2004S

(Dual diode)

2x300

5

Vishay

(402) 563-6866

www.vishay.com

BAS21

250

(Single diode)

1.5

Philips Semiconductor

(800) 234-7381

www.philips.com

ISS306

(Dual Diode)

2x250

3

Toshiba

(949) 455-2000

www.semicon.

toshiba.co.jp

3420fa

12

Share Link: