Low noise buck-boost charge pump saves space and reduces EMI

Linear Technology has announces the LTC3246, a compact, low noise buck-boost charge pump with integrated watchdog timer capable of up to 500mA of output current. The device uses multimode switched capacitor conversion to maintain regulation over a wide 2.7V to 38V input voltage range and produces a regulated 3.3V, 5V, or externally adjustable (2.5V to 5V) output. Internal circuitry automatically selects a conversion ratio of 2:1, 1:1 or 1:2 to optimize efficiency as input voltage and load conditions vary. Low operating current (20µA regulating with no load, 1.5µA in shutdown), low EMI switching and low external device count (three small ceramic capacitors and no inductors) make the device ideal for noise-sensitive space constrained automotive applications such as ECU/CAN transceiver supplies, as well as industrial housekeeping supplies and efficient low power 12V to 5V conversion. The device’s switched capacitor architecture with inherent soft switching provides lower radiated noise and EMI compared with conventional switching regulators. Timing control for the reset timeout and the windowed watchdog timeout can be adjusted using external capacitors on the RT and WT pins, or fixed internally via pin strapping. The accurate threshold of the reset input can be used for additional supply monitoring, or can be configured as a pushbutton reset. Other features include stability with ceramic capacitors, foldback current limiting to prevent excessive current flow during start-up, plus short-circuit and thermal protection.