EV4034-S-00A – UNIVERSAL INPUT, 5W, GU10 LED DRIVER

EV4034-S-00A Rev.1.0

www.MonolithicPower.com

6

12/19/2012

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CIRCUIT DESCRIPTION

The EV4034-S-00A is configured for a single-

stage, flyback topology. It uses primary-side-

control to simplify the schematic and reduce

BOM costs. It can also achieve an accurate LED

current.

The input stage consists of FR1 and DB1. FR1

protects against component failure or some

excessive short events, and can restrain the

inrush current.

The π filter (C1, L1, and C2) guarantees that the

conducted EMI meets the EN55015 standard.

The snubber circuit (R2, R3, D1, and C3)

reduces the drain-source voltage spike.

R4, C4, and D2 provide the VCC power supply.

The resistor divider (R5 and R6) provides open-

lamp protection by sampling the voltage on the

primary auxiliary winding. When an open occurs,

the output voltage remains constant.

CY1 is a Y capacitor that lowers common-mode

noise to ensure a sufficient EMI margin. T1 is the

power transformer, the structure of which is also

very important to pass EMI test.

D3, C5, and R7 compose output circuit. D3 is a

Schottky diode for better efficiency. C5 is a

ceramic capacitor for lower output-voltage ripple

and R7 is the dummy load for open-lamp

protection.