The LT3964 operates with fixed-frequency, current-mode control and operates as a constant-current and constant-voltage source with accurate current regulation to provide optimal LED lighting in automotive, industrial and architectural lighting applications. Both channels operate simultaneously at full current load Operation can produce efficiencies above 94%.
The device's 400kHz I2C interface greatly simplifies digital PWM dimming, eliminating the need to provide a PWM signal from the microcontroller to the LED driver, but setting the internal registers with the desired dimming duty cycle, which is synchronized to the internal clock. This provides a dimming ratio up to 8192: 1 and eliminates the beat frequency caused by the PWM signal and the internal oscillator being out of sync or, in analog dimming, with an 8-bit scale factor set by I2C The ratio of control voltage to LED current is set to allow greater control over analog dimming regulation. The device also offers 1000: 1 external PWM dimming and 10: 1 analog dimming.
The switching frequency of the LT3964 can be set from 200kHz to 2MHz, or it can be synchronized to an external clock signal. The LED driver's protection features include open and short LED fault detection, and LED overcurrent and overvoltage detection, all via I2C Interface Report. Overheating Shutdown provides an additional layer of protection.
The LT3964EUHE is available in a thermally enhanced 36-lead 5mm x 6mm QFN package and is available in three temperature-grade versions, with extended and industrial temperature versions operating from -40 ° C to 125 ° C (junction temperature) and high temperature versions in the - 40 ° C to 150 ° C range of operation.
Performance Summary: LT3964
• Two Independent Synchronous Step-Down Single-Chip LED Drivers • 1.6A Output Current per Channel • I2C Interface to Set Dimming Ratio and Monitor Faults • 8192: 1 I2C True Color PWM ™ Dimming • Switching Frequency up to 2MHz
