Synchronous boost LED controller for automotive power systems
Analog Devices announced the Power by Linear LT3762, a 60 V output, high efficiency, synchronous, boost LED driver controller with a programmable internal LED PWM signal generator and spread spectrum frequency modulation that yields low EMI noise. The LT3762 includes a rail-to-rail current sense amplifier, enabling high-side or low-side current sensing that, in addition to synchronous boost, facilitates synchronous buck-mode and buck-boost mode topologies and nonsynchronous SEPIC designs. The LT3762’s 2.5 V to 38.5 V input voltage range and synchronous operation make it ideal for automotive power systems, portable instruments, and industrial applications. An auxiliary on-chip buck-boost converter provides the necessary gate drive voltage in low-voltage systems, and when combined with a low 500 µA maximum quiescent current and 1 µA shutdown current (TA = 25 C), it results in high efficiency over wide input voltage and output current ranges. In systems where EMI is a concern, the LT3762’s optional spread spectrum frequency modulation can be enabled to reduce the effective switching frequency noise. An on-chip PWM signal generator is synchronized to the internal oscillator for lowest noise performance. Internal PWM generation provides 250:1 dimming; external 3000:1 dimming or analog dimming can also be employed. Other features include current mode operation with cycle-by-cycle current limiting, adjustable 100 kHz to 1 MHz switching, programmable undervoltage lockout, open LED and short-circuit protection with fault status indicators, LED overcurrent protection, and thermal shutdown. The LT3762 is available in thermally enhanced 28-lead TSSOP and 4 mm x 5 mm QFN packages. Three temperature grades are offered, with operation from –40 C to 125 C (junction) for the extended and industrial grades, and a high temperature grade of –40 C to 150 C.