Silan

Microelectronics

SD670XSC_Datasheet

PIN CONFIGURATIONS

VCC

CS

NC

4

3

2

5

6

1

7

ROVP

DRAIN

GND

DRAIN

PIN DESCRIPTION

Pin No.

Pin Name

I/O

Description

1

ROVP

I/O

OVP pin, short-circuited or connected to GND through a resistor

2

NC

--

No connection

3

CS

I

Sense current pin

4

VCC

POWER

Power supply

5, 6

DRAIN

O

Drain of internal high voltage MOSFET

7

GND

GND

GND

FUNCTION DESCRIPTION

SD670XSC is a non-isolated LED driver IC adopting BUCK structure with internal high voltage power MOSFET. The

function is described below.

Start control

For SD670XSC, no auxiliary winding is needed. The bus voltage charges capacitor of VCC through start resistor. The

operating current should be as low as possible for high conversion efficiency. It features undervoltage protection at

VCC and the on/off threshold value are 12V and 7.5V. The hysteresis characteristic guarantees that the IC can be

powered by the capacitor during the start.

Constant current accuracy control

IC senses the MOSFET current, which is input to Gm amplifier together with internal reference voltage for error

amplification, to obtain high constant current accuracy and high linear/load regulation rate.

CS voltage and 400mV reference voltage are the inputs of Gm amplifier, and then the output is integrated through

internal COMP capacitor.

Output current is given by:

IOUT=400mV/2*RCS.

HANGZHOU SILAN MICROELECTRONICS CO.,LTD

Rev.:1.2

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