1

4

3

2

14

11

12

13

N/C

N/C

ASNS

DIM

GND

FLTR1

COFF

FLTR2

5

10

N/C

BLDR

6

N/C

7

ISNS

9 VCC

8 GATE

1

4

3

2

10

7

8

9

FLTR1

GATE

BLDR

COFF

ASNS

DIM

5

6

FLTR2

GND

LM3445

SNVS570L – JANUARY 2009 – REVISED MAY 2013

www.ti.com

DEVICE INFORMATION

TOP MARK

LM3445M/NOPB

SULB

LM3445MM/NOPB

SULB

LM3445MMX/NOPB

LM3445M

LM3445MX/NOPB

LM3445M

(1)

For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI

web site at www.ti.com.

Connection Diagram

Top View

Top View

Figure 1. 10-Pin VSSOP

Figure 2. 14-Pin SOIC

Package Number DGS

Package Number D

PIN DESCRIPTIONS

SOIC

VSSOP

Name

Description

12

1

ASNS

PWM output of the triac dim decoder circuit. Outputs a 0 to 4V PWM signal with a duty cycle

proportional to the triac dimmer on-time.

13

2

FLTR1

First filter input. The 120Hz PWM signal from ASNS is filtered to a DC signal and compared to a 1 to

3V, 5.85 kHz ramp to generate a higher frequency PWM signal with a duty cycle proportional to the

triac dimmer firing angle. Pull above 4.9V (typical) to tri-state DIM.

14

3

DIM

Input/output dual function dim pin. This pin can be driven with an external PWM signal to dim the

LEDs. It may also be used as an output signal and connected to the DIM pin of other LM3445s or

other LED drivers to dim multiple LED circuits simultaneously.

1

4

COFF

OFF time setting pin. A user set current and capacitor connected from the output to this pin sets the

constant OFF time of the switching controller.

3

5

FLTR2

Second filter input. A capacitor tied to this pin filters the PWM dimming signal to supply a DC voltage

to control the LED current. Could also be used as an analog dimming input.

4

6

GND

Circuit ground connection.

7

7

ISNS

LED current sense pin. Connect a resistor from main switching MOSFET source, ISNS to GND to set

the maximum LED current.

8

8

GATE

Power MOSFET driver pin. This output provides the gate drive for the power switching MOSFET of the

buck controller.

9

9

Input voltage pin. This pin provides the power for the internal control circuitry and gate driver.

10

10

BLDR

Bleeder pin. Provides the input signal to the angle detect circuitry as well as a current path through a

switched 230

Ω resistor to ensure proper firing of the triac dimmer.

2,5,6,11

-

N/C

No Connect

2

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