DC1199A - Schematic9/24/2009
Demonstration circuit 1199A is a 16-Channel Buck Mode LED Driver featuring the LT3595EUHH. The circuit is optimized to drive 16 channels of three series LEDs at 30mA, though the LT3595 is capable of driving up to 10 LEDs at 50mA per channel. Each channel has three series white LEDs and they are stuffed on the PCB. The LT3595 features a wide input voltage range, integrated components, externally set LED current, high pwm dimming range, high efficiency, shutdown, open LED protection, and 2MHz switching frequency.
The 100mA, 45V fully integrated switches help drive up to 10 LEDs per channel in series at 50mA each. Internal catch diodes reduce external component count and circuit size. PWM dimming is as high as 1000:1 at 100Hz over the entire input voltage range.
There are three input power terminals: VIN ranges from 15V up to 45V and is used for powering the LEDs, VCC powers the LT3595 and the pwm gates, and µVIN (6-12V) powers the onboard PIC microprocessor. The PIC allows the board to demonstrate some preprogrammed patterns and PWM dimming. Although the range of the LT3595 VCC pin goes down to 3V, 5V is needed for the PWM signal gates to work properly with the PIC.