AL9901

Document number: DS37713 Rev. 1 - 2

2 of 20

www.diodes.com

March 2015

© Diodes Incorporated

AL9901

Pin Descriptions

Pin Name

U-DFN5040-10

SO-16

Functions

Gate

1

14

Gate of Internal MOSFET switch.

NC

2

1, 2, 4, 10,16 No connection

PWM

3

5

Low Frequency PWM Dimming pin, also Enable input. Internal 200k

pull-down to GND

4

6

Internally regulated supply voltage, 7.5V nominal.

Can supply up to 1 mA for external circuitry. A sufficient storage capacitor is used to provide

storage when the rectified AC input is near the zero crossing.

LD

5

7

Linear Dimming input. Changes the current limit threshold at current sense comparator and

changes the average LED current.

6

8

Oscillator control.

A resistor connected between this pin and ground puts the AL9901 into fixed frequency mode and

sets the switching frequency. A resistor connected between this pin and Gate pin puts the AL9901

into fixed off-time mode and determines the off-time.

7

9

Input voltage

CS

8

11

Senses LED string and internal MOSFET switch current

GND

9

12

Device ground

DRV

10

13

off time mode.

SO

11

15

Source of the internal MOSFET Switch

SW

12

3

Drain of the internal MOSFET switch.

EP1

EP1

NA

Exposed Pad 1(bottom). Drain connection of internal power MOSFET.

EP2

EP2

NA

Exposed Pad 2 (bottom). Substrate connection of control IC. Connect to GND directly underneath

the package and large PCB area to minimise junction to ambient thermal impedance.

Functional Block Diagram