Datasheet
1
4
3
2
14
11
12
13
N/C
N/C
ASNS
DIM
GND
FLTR1
COFF
FLTR2
5 10N/C BLDR
6N/C
7ISNS
9
VCC
8 GATE
1
4
3
2
10
7
8
9
I
SNS
FLTR1
GATE
BLDR
COFF
V
CC
ASNS
DIM
5 6FLTR2 GND
LM3445
SNVS570L –JANUARY 2009–REVISED MAY 2013
www.ti.com
DEVICE INFORMATION
ORDER NUMBER
(1)
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 V
CC
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 230Ω resistor to ensure proper firing of the triac dimmer.
2,5,6,11 - N/C No Connect
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