LM3466 Datasheet, PDF (1/23 Pages) Texas Instruments – Multi-String LED Current Balancer for Use with Constant-Current Power Supplies

LM3466
www.ti.com
SNOSB96F – JUNE 2011 – REVISED NOVEMBER 2013
Multi-String LED Current Balancer for Use with Constant-Current Power Supplies
Check for Samples: LM3466
FEATURES
1
•2 Easy to Design for Lighting Systems
Consisting of Multiple LED Strings (Supports
Modular Design)
• Automatically Balances the Current of Every
Active LED String, even the Forward Voltage
of Each String is Different
• Easy to Pre-Set and Fine-Tune Current Ratio
Among LED Strings (e.g., color temperature
adjustment or CRI Enhancement)
• ±1% Current Accuracy at Room Temperature
and ±1.5% Over Temperature
• Maintains Constant Output Power if Some
Strings Open (inactive) by Automatically
Balancing the Current of Remaining Active
LED Strings
• Works with a Constant Current Power Supply
(ac/dc or dc/dc), and no Communication
to/from the Constant Current Power Supply is
Required
• Operates with Minimum Voltage Overhead to
Maximize Power Efficiency
• Wide Input Voltage Range from 6 V to 70 V
• Fault Status Output
• Thermal Shutdown
• Integrated 70-V, 1.5-A MOSFET with 2.06 A
Current Limit
• Maximum 70-V per LED String, 20 LEDs
• Linear Circuitry Does Not Deteriorate EMI
• DDA-8 Exposed Thermal Pad and TO220-7
Packages
DESCRIPTION
The LM3466 integrates a linear LED driver for lighting
systems which consist of multiple LED strings
powered by a constant current power supply. It
balances the current provided by the supply in a pre-
set ratio for each active LED string, where an active
string is a fully turned on LED string, regardless of
the number of strings connected to the supply or the
forward voltage of each LED string. If any LED string
opens during operation, the LM3466 automatically
balances the supply current through all of the
remaining active LED strings. As a result, the overall
brightness of the lighting system is maintained even if
some LED strings open during operation.
The LM3466 lighting system is simple to design
owing to a proprietary control scheme. To minimize
the component count, the LM3466 integrates a 70-V,
1.5-A, N-channel power MOSFET with a current limit
of 2.06 A. To add one more LED string to the system,
only a single resistor, a capacitor, and a LM3466 are
required. Other supervisory features of the LM3466
include under-voltage lock-out, fault reporting,
thermal latch off, and thermal shutdown protection.
The LM3466 consists of only linear circuitry so that
the EMI of the application circuit is not deteriorated.
The LM3466 lighting system is EMI friendly if the
constant current power supply used is complied to
EMI standards. The LM3466 is available in the DDA-
8 exposed thermal pad and TO220-7 packages.
SIMPLIFIED APPLICATION
V_IN
Connect to
VIN pin of
C_IN
another
LM3466
APPLICATIONS
• Street Lamps
• Solid State Lighting Systems
C_LED
LM3466
ILED
VEQ
VIN
SEN
COMM
SRC
GND
R_SEN
Connect to
VEQ pin of
another
LM3466
Connect to
COMM pin
of another
R_EQ
LM3466
C_EQ
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2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
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