User manual

PWM Dimming Control

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The IOUTADJ pin can be biased by a positive voltage in the range of 0V to 2.5V across the terminals

TP31and TP39. If the IOUTADJ pin is going to be biased by an external voltage source, the R10 and R11

should be removed.

12 PWM Dimming Control

The LM3463 evaluation board allows three different modes of PWM dimming control:

• Direct PWM Dimming Mode

• Serial Interface Mode

• DC Interface Mode

• The mode of PWM dimming control is selected by changing the position of the shunt jumper of J8.

Mode of dimming control Setting of J8

Direct PWM dimming mode Short Pos. 2–3

Serial interface mode Open

DC interface mode Short Pos. 1–2

Using PWM dimming control, the six output channels of the board are grouped into four individual groups

which are controlled by four individual PWM signals at the terminals TP12, TP14, TP16 and TP18.

Terminal Involved channels

TP12 CH0, CH1

TP14 CH2, CH3

TP16 CH4

TP18 CH5

The terminals J4, J5, J6 and J7 are used to connect the DIM01(TP12), DIM23(TP14), DIM4(TP16) and

DIM5(TP18) pins of the LM3463 to either VCC or GND. The jumpers on these terminals should be

removed if external dimming control signals are applied to the board.

Direct PWM Dimming Mode

In the direct PWM dimming mode, the board accepts standard active high TTL level PWM signals to

perform dimming control. The minimum on duty is generally limited by the gate capacitance of the external

MOSFETs. Normally, an 8 µs minimum on time is suggested.

Serial Interface Mode

In the serial interface mode, the on duty of each output channel is controlled by a data byte of 8 bits wide.

In this mode the terminals TP12, TP14 and TP16 on the board comprise a serial data interface to receive

data bytes from external data source. The connection to the DIM5 pin is not used and should be

connected to GND by shortening the pins 2 and 3 of J7. The functions of the TP12, TP14 and TP16 in the

serial interface mode are as listed in the following table:

Serial Interface Mode

Terminal Function

TP12 Serial data input

TP14 Clock signal input

TP16 End Of data Frame (EOF) signal input

AN-2255 LM3463 Evaluation Board SNVA642A–May 2012–Revised May 2013

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