On Semiconductor NCL30000 Evaluation Board NCL30000LED1GEVB NCL30000LED1GEVB データシート

1

MFP

The multi-function pin is connected to the internal error amplifier. By pulling this pin below the V

uvp

 threshold, the

controller is disabled. In addition, this pin also has an over voltage comparator which will disable the controller in the

event of a fault.

2

COMP

The COMP pin is the output of the internal error amplifier. A compensation network is connected between this pin

and ground to set the loop bandwidth. Normally this bandwidth is set at a low frequency (typically 10 Hz − 20 Hz) to

achieve high power factor and low total harmonic distortion (THD).

3

C

t

The C

t

 pin sources a regulated current to charge an external timing capacitor. The PWM circuit controls the power

switch on time by comparing the C

t

 voltage to an internal voltage derived from V

Control

. The C

T

 pin discharges the

external timing capacitor at the end of the on time cycle.

4

CS

The CS input is used to sense the instantaneous switch current in the external MOSFET. This signal is filtered by an

internal leading edge blanking circuit.

5

ZCD

The voltage of an auxiliary zero current detection winding is sensed at this pin. When the ZCD control block circuit

detects that the winding has been demagnetized, a control signal is sent to the gate drive block to turn on the

external MOSFET.

6

GND

This is the analog ground for the device. All bypassing components should be connected to the GND pin with a short

trace length.

7

DRV

The high current capability of the totem pole gate drive (+0.5/−0.8 A) makes it suitable to effectively drive high gate

charge power MOSFETs. The driver stage provides both passive and active pull down circuits that force the output to

a voltage less than the turn-on threshold voltage of the power MOSFET when V

CC(on)

 is not reached.

8

V

CC

This pin is the positive supply of the controller. The circuit starts to operate when V

CC

 exceeds V

CC(on)

, nominally

12 V and turns off when V

CC

 goes below V

CC(off)

, typically 9.5 V. After startup, the operating range is 10.2 V up to

20 V.

Q1

EMI

FILTER

1

2

3

4

8

7

6

5

Cin

RCS

Ï

Ï

D1

C1

Ccomp

Ctim

Ry

RLED

RZCD

RL

R2

R1

RSU

MFP

COMP

VCC

DRV

GND

ZCD

CT

CS

AC

Line

Input

Ï

Dout

COUT

ÏÏ

ÏÏ

Rc

Rt

Ï

Ra

Rb

Rx

GND

4

3

2

1

7

8

5

6

IN1+

IN1−

IN2−

IN2+

OUT1

OUT2

VCC

+

−

+

−

Cc

Cv