Constant current LED driver controller focuses on LED lighting applications
The R1580 solution represents a new concept for a wide range of applications using LED driver control gear, such as residential and office lighting, industrial lighting for machine vision purposes, automotive lighting and art and museum lighting.
The multi-purpose device R1580N eliminates flickering and EMI noise issues. The device has a specific DIM input pin to connect a signal for dimming the LED brightness level. Traditional Pulse Width Modulation (PWM) dimming is obtained by applying full current to the LED at a reduced duty cycle. In order to obtain 50% LED brightness, full current is applied at a 50% duty cycle (50% on, 50% off). The pulsing signal is also forwarded to the gate of the LED driver MOSFET resulting in a fast flickering light source. When using such light source for recording a video or taking photos, this flickering effect will be visible and decrease the quality of the footage. In addition, the PWM controlled LED driver MOSFET also causes EMI noise, possibly affecting other sensitive electronic circuits. The R1580 however has a different approach. The PWM input signal connected to the DIM pin is internally converted into a linear DC voltage applied to the gate of the LED driver MOSFET, in this way eliminating both flickering and EMI noise and resulting in high quality footage
The R1580 also has a wide dimming range; from 100% to 1.0% or even to 0.5% brightness level, whereas conventional products can dim down to 5%. One major advantage of dimming to a 0.5% brightness level when used in an RGB LED configuration, is the extension of the colour temperature range. The light source is able to show more colour variations. Also, when dimming to a minimum the LED will not simply turn off at the 5% dimming level but continues to dim to 0.5%.
The R1580N provides a constant current. The constant-current source eliminates changes in current due to variations in forward voltage, resulting in a constant LED brightness. The input power supply regulates the voltage across a current-sense resistor. The power supply reference voltage and the value of the current sense resistor determine the LED current. Multiple LEDs should be connected in a series configuration to maintain an identical current flowing in each LED.
With an external LED driver MOSFET to add to the R1580, the circuit can be adapted to suit the requirements of the specific application.
The device comes in a version with a dimming range from 100% to 1.0%, a version dimming to 0.5% and a version dimming to 1.0% but with a lower stand-by current consumption. The R1580 is available in a 6-pin SOT-23-6 package for applications that require a small footprint solution when board space is limited.
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