User manual

SNS

FLTR1

GATE

BLDR

COFF

ASNS

DIM

5 6FLTR2 GND

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Pin-Out

4 Pin-Out

Figure 1. 10-Pin VSSOP

Table 1. Pin Description 10 Pin VSSOP

Pin No Name Description

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.

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.

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 LM3445 or LED drivers to dim

multiple LED circuits simultaneously.

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.

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.

6 GND Circuit ground connection.

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

maximum LED current.

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

buck controller.

9 V

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

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

switched 230Ω resistor to ensure proper firing of the triac dimmer.

SNVA442C–June 2010–Revised May 2013 AN-2061 LM3445 A19 Edison Retrofit Evaluation Board

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