Linear Technology LTC3617 switching regulator

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Linear Technology has introduced the LTC3617, a high-efficiency, monolithic synchronous step-down switching regulator, capable of generating a bus termination voltage for DDR/DDR2/DDR3 and future standard memory applications requiring sourcing and sinking of current.

An internal resistor divider sets the VTT DDR termination supply and VTTR reference voltages equal to half the voltage applied to the input, with output current capability of ±6 A (sinking/sourcing) at VTT and ±10 mA at VTTR.

The outputs can operate operation down to 0.5 V. The device operates from an input voltage range of 2.25 to 5.5 and allows switching frequencies to 4 MHz.

The internal synchronous top and bottom power switches have an RDS(ON) of 35 and 25 mΩ, enabling the regulator to attain efficiencies to 93%, eliminating the need for an external catch diode while minimising external component count and board space.

The device uses constant frequency, current-mode architecture. The switching frequency can be set between 300 kHz and 4 MHz by a single external resistor. This high-frequency capability enables use of smaller capacitor values, while maintaining low output voltage ripple.

For noise-sensitive switching applications, the device can be synchronised to an external clock up to 4 MHz.