Analog Devices offers 4MHz synchronous dual output regulator in compact QFN
Efficient, 4.0MHz synchronous dual output buck regulators, the LTC3636 and the LTC3636-1 incorporate a constant frequency/controlled on-time, current mode control scheme with phase lockable switching frequency.
Available from Analog Devices, which acquired Linear Technology earlier this year, the LTC3636 and LTC3636-1 are based on an innovative design architecture that reduces conducted and radiated emissions, says the company. The LTC3636 and LTC3636-1 can deliver up to 6.0A of continuous output current from each channel or generate a two-phase single output up to 12A. The parts accommodate output voltages as low as 0.6V from a compact 4.0 x 5.0mm quad flat no-leads (QFN) package.
The switching frequency is user-programmable from 500kHz to 4.0MHz, enabling the use of tiny, low cost capacitors and inductors. It may also be synchronised to an external clock signal. The LTC3636 and LTC3636-1 operates from an input voltage of 3.1V to 20V. Output voltage sense ranges are 0.6V to 5.0V for the LTC3636 and 1.8V to 12V for the LTC3636-1. These output ranges make them suitable for dual-cell Li-Ion applications as well as five and 12V intermediate bus systems.
Each channel of the LTC3636 and LTC3636-1 uses internal switches with RDS (ON) of only 32 and 18-mOhm to deliver efficiencies up to 95 per cent. The control architecture enables the regulators to achieve duty cycles as low as five per cent while maintaining switching frequencies up to 2.25MHz, making them suitable for high step-down ratio applications such as 12VIN to 1.8VOUT conversions. The two channels run 180 degrees out-of-phase, minimising the size of both input and output capacitance, says Analog Devices. The dual outputs may be combined in a two-phase configuration for up to 12A output current. Burst Mode operation is used to maximise light load efficiency, requiring 600-microA at no load. For applications requiring the lowest possible noise, the LTC3636 and LC3636-1 can be configured to run in forced continuous operation, reducing supply ripple and potential radio frequency interference. Additional features include a die temperature monitor, power good voltage monitors, output voltage tracking capability, independent soft-start capability for each channel, short-circuit protection, input overvoltage and over-temperature protection.
The LTC3636 is available in E- and I-grade versions, guaranteed to operate over -40 to +125 degree C operating junction temperature. All versions are available from stock.