Datasheet
Design Procedure
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Figure 5. LM3466 Evaluation Board Connection Diagram
3 Design Procedure
The LM3466 evaluation board has 5 channels driving five LED strings powered by a constant current
power supply (I
S
= 1.75A). It is expected that the current of every LED string is 0.35A. From the schematic
(see Figure 4), each channel consists of an LM3466 (U
i
), a sense resistor (R
i1
), and two capacitors (C
i1
and C
i2
), where i = 1 to 5. An RC circuit connecting the VEQ pin to ground is required for the whole circuit.
The above components are determined as follows.
Step 1: Determine the sense resistor
The current provided by the constant current power supply is equalized through each channel in a pre-set
ratio determined by the sense resistor R
i1
. This LM3466 evaluation board is designed so that the current of
each channel is the same, the sense resistor of each channel is designed to be the same. It is
recommended that the nominal voltage of the SEN pin V
SEN
should be around 0.3 V. Therefore, R
i1
is
selected to be 1 Ω. As a result, V
SEN
should be 0.35 V if the LED current is 0.35A.
4
AN-2182 LM3466 Demonstration Board Reference Design SNOA566A–October 2011–Revised April 2013
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