User manual

LM3445 Device Pin-Out
30126902
Pin Description 10 Pin MSOP
Pin # 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
CC
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.
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