www.powerint.com

A

11/02

DI-12

For the latest updates, visit our Web site: www.powerint.com

Power Integrations reserves the right to make changes to its products at any time to improve reliability or manufacturability.

Power Integrations does not assume any liability arising from the use of any device or circuit described herein, nor does it convey any

license under its patent rights or the rights of others. The products and applications illustrated herein (including circuits external to the

products and transformer construction) may be covered by one or more U.S. and foreign patents or potentially by pending U.S. and foreign

patent applications assigned to Power Integrations. A complete list of Power Integrations’ patents may be found at www.powerint.com.

The PI Logo, TOPSwitch, TinySwitch, LinkSwitch and EcoSmart are registered trademarks of Power Integrations, Inc.

PI Expert is a trademark of Power Integrations, Inc. ©Copyright 2002, Power Integrations, Inc.

Figure 2. Output Characteristic (V

14

12

0

00.2

0.4

0.6

0.8

1.0

Output Current (A)

4

8

1.2

16

230 VAC

90 VAC

Ambient Temperature = 30

°C

WORLD HEADQUARTERS

AMERICAS

Power Integrations, Inc.

San Jose, CA 95138 USA

Customer Service:

Phone:

+1 408-414-9665

Fax:

+1 408-414-9765

e-mail: usasales@powerint.com

CHINA

Power Integrations International

Holdings, Inc.

China

Phone:

+86-755-8367-5143

Fax:

+86-755-8377-9610

e-mail: chinasales@powerint.com

SINGAPORE

Power Integrations, Singapore

Republic of Singapore 308900

Phone:

+65-6358-2160

Fax:

+65-6358-2015

e-mail: singaporesales@powerint.com

JAPAN

Power Integrations, K.K.

Keihin-Tatemono 1st Bldg.

Japan

Phone:

+81-45-471-1021

Fax:

+81-45-471-3717

e-mail: japansales@powerint.com

EUROPE & AFRICA

Power Integrations (Europe) Ltd.

United Kingdom

Phone:

+44-1344-462-300

Fax:

+44-1344-311-732

e-mail: eurosales@powerint.com

KOREA

Power Integrations

International Holdings, Inc.

Seoul, Korea

Phone:

+82-2-782-2840

Fax:

+82-2-782-4427

e-mail: koreasales@powerint.com

TAIWAN

Power Integrations

International Holdings, Inc.

Taipei, Taiwan

Phone:

+886-2-2727-1221

Fax:

+886-2-2727-1223

e-mail: taiwansales@powerint.com

INDIA (Technical Support)

Innovatech

Bangalore, India

Phone:

+91-80-226-6023

Fax:

+91-80-228-9727

e-mail: indiasales@powerint.com

APPLICATIONS HOTLINE

APPLICATIONS FAX

World Wide +1-408-414-9660

World Wide +1-408-414-9760

For battery detection and monitoring, R11, R12 and Q2

reduce the output voltage to approximately 8 V when a 5 V

signal is applied to R12. This allows the battery voltage to

be measured, giving the state of charge.

Key Design Points

• The value of R3 sets the typical output current limit

threshold given by: R3 = 0.6 / I

• Rate R3 and R5 accordingly for power dissipation (1 W).

• Ensure total voltage across R3 and R5 is greater than

1.5 V at I

• Ensure voltage at cathode of D3 is >6 V at I

Add

additional bias winding turns, if necessary, to maintain

output current control to 0 V (output shorted).

• RT1: Philips part # 2322-640-54472.

• Select tolerance of U2, R7, R8 and R9 to give the desired

overall CV tolerance (R7, R8 and R9 as 0.1%; R10 as 1%

and U2 as 0.5% gives overall tolerance <2%).

TRANSFORMER PARAMETERS

Core Material

TDK PC40 EE22/29/6-Z,

Gap for A

2

Bobbin

YC 2204 (Ying Chin)

Winding Details

Primary: 56T, 30 AWG

Bias: 8T, 2 x 30 AWG

Secondary: 8T, 28 AWG T.I.W.

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

Inductance

Primary: 475

µH ±10%,

Leakage: 35

µH (maximum)

Primary Resonant Frequency

300 kHz (minimum)

Winding Order

(Pin Numbers)

Primary (2-1), tape, Bias (4-3),

tape, Secondary (7,8-5,6)

Figure 3. Cell Charging Voltage vs Temperature.

2.30

2.25

-10.0

0.0

10.0

20.0

30.0

40.0

2.15

2.20

50.0

2.35

2.40

2.45

60.0

Typical Limit

Table 1. Transformer Construction Information.