Linear Technology - Dual output step-down LTC3256

The LTC®3256 is a wide input range switched capacitor
step-down DC/DC converter that produces two regulated
outputs: a 5V output via direct connection to the charge
pump output, and a 3.3V output via a low dropout (LDO)
linear post-regulator. The device provides up to 350mA
of total output current. At 12V VIN and maximum load on
both outputs, power dissipation is reduced by over 2W
compared to a dual LDO regulator solution.

 The LTC3256 maximizes efficiency by running the charge
pump in 2:1 mode over as wide an operating range as possible,
and automatically switches to 1:1 mode as needed
due to VIN and load conditions. Controlled input current and
switching slew rates minimize conducted and radiated EMI.
An integrated watchdog timer, independent power good
outputs and reset input ensure reliable system operation
and fault monitoring. A buffered 1.1V reference output
enables system self-testing for safety critical applications.