DC2630A

Features and Benefits

Demonstration circuit 2630A is an I²C programmable quad channel monolithic boost LED driver featuring the LT3966. It drives four separate strings of LEDs (up to  50V) at 125mA when V_IN is between 9V and 18V. DC2630A runs at 2MHz switching frequency. Its four channels are capable of powering LED strings which can have different currents, voltages, or dimming ratios. Each channel can be independently controlled via I²C communications or analog inputs. DC2630A can be configured to run in either mode by modifying the ADDR pin settings. It is protected against output overcurrent, overvoltage events, and reports open and short LED fault events by latching an alert pin. In I²C mode, faults can be enabled or disabled. A DC2026C Linduino^® One demonstration circuit is used to interface with the board by directly connecting it with a QuikEval^™ ribbon cable and provided command line interface code.

The LT3966 has an input voltage range from 3V to 60V. Each boost channel has an integrated 60V 1.6A low-side power switch. It has adjustable switching frequency between 300kHz and 2MHz and can be synchronized to an external clock source. Additionally, LT3966 can be programmed to output its own master clock to sync other devices. The high side PWMTG MOSFET drivers assist with PWM dimming and fault protection. The LT3966 channels can be configured to operate as a ground-referenced step-up (boost) LED driver, or as a floating output LED driver to perform step-down (buck mode) or step-up/step-down (buck-boost mode) operation.

Each channel of the LT3966 can be independently dimmed by applying a PWM signal or CTRL voltage to the corresponding channel CTRL/PWM pin while operating in non-I²C mode. In I²C mode, each channel has a maximum of 13 bits of PWM dimming resolution and 8 bits of analog dimming resolution.

Small ceramic input and output capacitors are used to save space and cost. The open LED overvoltage protection uses the IC’s constant-voltage regulation loop to regulate the output to approximately 57V if the LED string is opened.

Undervoltage lockout can be adjusted on the circuit with a few simple resistor choices. The output voltage (overvolt-age protection) can be adjusted by changing the feedback resistors for different string voltages. Other components may need to be changed to accommodate the change in output voltages as well.

The LT3966 data sheet gives a complete description of the device, operation and applications information. The data sheet must be read in conjunction with the demo manual for DC2630A. The LT3966EUJ is assembled in a 40-lead plastic 6mm × 6mm QFN package with a thermally enhanced ground.