Dual output power supply features low noise

A high voltage low noise dual output power supply from Linear Technology is said to take a single positive input and generates 5V and 3.3V step-down supplies with high efficiency and no inductors.

The device features an input voltage range from 5.5V to 38V and independently enabled dual outputs – a 5V, 100mA supply and a 250mA, 3.3V LDO regulator – with an available output current of 350mA. This combination is said by Linear to offer lower power dissipation than a dual LDO solution.

The device is targeted at a range of applications requiring low noise, low power rails from a high voltage input, including such as automotive ECU/CAN transceiver supplies, industrial/telecom housekeeping and general purpose low power 12V to 5V and 3.3V conversion.

The LTC3256 has been designed to maximise efficiency by running the charge pump in 2:1 mode over as wide an operating range as possible. It will switch automatically to 1:1 mode as needed, dependent upon VIN and load conditions. Controlled input current and soft switching reduce conducted and radiated EMI.

The device has a quiescent current of 20µA with both outputs regulating (no load) and 0.5µA in shutdown. Integrated watchdog timer, independent power good outputs and reset input contribute to reliable system operation and enable fault monitoring. Meanwhile, a buffered 1.1V reference output enables system self-testing diagnostics for safety critical applications. Other safety features include overcurrent fault protection, over temperature protection and tolerance of 38V input transients.

The LTC3256 is supplied in a thermally enhanced 16lead MSOP with a backside thermal pad. Three operating temperature ranges are available: -40 to 125°C; -40 to 150°C; -55 to 150°C.