EP11 datasheet(7/46 Pages) POWERINT

7 / 46 page

EPR-00011 - 70 W Adapter

22-Jan-01

Page 7 of 46

Power Integrations Inc

Tel: +1 408 523 9200 Fax: +1 408 523 9300

www: http://www.powerint.com

Schematic

Figure 3 - 70W TOP249Y Power Supply Schematic

3.1

Description

The EP11 is a low-cost flyback switching power supply using the TOP249Y integrated

circuit from the TOPSwitch-GX family.

The circuit shown in Figure 3 details a 19 V,

70 W supply that operates from an input range of 85 to 265 VAC, suitable for applications

requiring either an open frame supply or an enclosed adapter.

AC power is rectified and filtered by BR1 and C7 to create the high voltage DC bus

applied to the primary winding of transformer (T1). Only a 150

µF capacitor is required

(2.1

µF/W) due to the wider DC

MAX of TOPSwitch-GX and the line feed forward function

provided by the LINE SENSE Pin.

The other side of the primary is driven by the

integrated high-voltage MOSFET within the TOP249Y. Diodes, D4 and D2 clamp the

DRAIN voltage spike caused by transformer leakage inductance to a safe value below

the 700 V maximum. Capacitor C6 is added in parallel with D2 to reduce zener clamp

dissipation.

The TOPSwitch-GX family provides new operating features and extended specifications.

The EP11 power supply is designed using several of these features. Resistors R14 and

R15 connected to the LINE SENSE pin (L) of TOPSwitch-GX (U1) are used to implement

EP11 Datasheet(PDF) 7 Page - Power Integrations, Inc.