POWER AND LINEAR IC SOLUTIONS

16-Channel Buck Mode LED Driver

The LT3595 from Linear Technology Corporation is a high performance LED driver designed to drive 16 independent channels of up to ten LEDs at currents of up to 50mA. Series connection of the LEDs provides identical LED currents, resulting in uniform brightness.



Power switches, Schottky diodes and compensation components are all internal, providing a small converter footprint and lower overall component cost. The high (2MHz) switching frequency permits the use of tiny, low profile inductors and capacitors. The device’s fixed frequency, current mode architecture delivers stable operation over a wide range of supply and output voltage.

A single external resistor sets the LED current for all 16 channels and dimming is controlled for each channel by Pulse Width Modulating the individual PWM pins. Relative current matching among the 16 drivers is 8% and the PWM dimming range is 5000:1.

Using appropriate external components recommended by Linear Technology Corporation, the LT3595 can drive a 10-LED string down to 15mA LED current while operating in continuous conduction mode. As current is reduced, the regulator enters discontinuous conduction mode and the currents in the external inductors reach zero during the discharge phase. Although this produces a ringing effect due to the LC tank circuit formed by the inductor in combination with the switch and external diode capacitance, this is not harmful, because far less spectral energy is contained in the ringing than in the switch transitions.

The LT3595 can accommodate input supply voltages between 4.5V and 45V and achieves a typical efficiency of 92%. It is supplied in a 5mm x 9mm x 0.75mm 56-pin QFN package.

Features

• 16-channel buck mode LED driver
• 4.5V to 45V input supply range
• Up to 50mA LED current per channel
• 100mA, 45V internal switches
• 8% relative LED current match at 20mA
• 5000:1 True Colour PWM™ dimming range
• LEDs disconnected in shutdown
• Internal Schottky diodes
• Low quiescent current
• 2MHz switching frequency
• Pin-selectable master LED current
• Typical efficiency 92%
• Open LED detection and thermal protection
• 56-pin 5mm x 9mm x 0.75mm QFN package

Applications

• LED video billboards
• LCD televisions
• Stadium and advertising displays

For further information, including a Datasheet for the LT3595, please click here