Buck-boost charge pump offers low conducted and radiated noise

Linear Technology Corporation announces the LTC3245, a versatile 250mA high voltage buck-boost charge pump that uses switched-capacitor fractional conversion to maintain regulation over a wide range of input voltage from 2.7V to 38V. Producing a regulated output of 3.3V, 5V or adjustable (2.5V to 5V), the device has internal circuitry that automatically selects the conversion ratio (2:1, 1:1 or 1:2) to optimize efficiency as input voltage and load conditions vary. Features such as a low operating current (18?A with no load, 4?A in shut­down) and low external device count (three small ceramic capacitors and no inductors) make the LTC3245 ideally suited for low power, space constrained automotive/industrial applications such as automotive ECU/CAN transceiver supplies, industrial housekeeping supplies and efficient low power 12V to 5V conversion. The LTC3245's unique constant frequency architecture with reduced switching edge rates provides lower conducted and radiated noise compared to conventional switching regulators. The device has pin selectable Burst Mode operation which allows the user to trade off low output ripple for better efficiency/lower quiescent current. Other IC features include low external parts count with ceramic capacitor stability, soft-start circuitry to prevent excessive current flow during startup, plus short circuit and thermal protection. The LTC3245 is available in a low-profile (0.75mm) 3mm x 4mm 12-lead DFN with backside thermal pad and a 12-lead MSOP package with backside thermal pad. E- and I-grade operating junction temperature is -40°C to +125°C, while H-grade is -40°C to +150°C. 1000-piece pricing for the E grade starts at $2.80 each, and devices are available from stock. Linear Technology