Analog Devices Inc./Maxim Integrated

The LTC3618 is a dual synchronous step-down regulator using a current mode, constant-frequency architecture. It provides a complete DDR solution with an input voltage range from 2.25V to 5.5V.The output of the first step-down regulator offers a high accuracy VDDQsupply. A buffered reference generates VTTR at 50% of VDDQIN and drives loads up to ±10mA. The second regulator generates the DDR termination voltage (VTT) equal to VTTR. Both regulators are capable of delivering ±3A of load current at 1MHz switching frequency.The operating frequency is externally programmable up to 4MHz, allowing the use of small surface mount inductors. 0°, 90°, or 180° of phase shift between the two channels can be selected to minimize input current ripple. For switching noise-sensitive applications, the LTC3618 can be synchronized to an external clock up to 4MHz.The LTC3618 is offered in leadless 24-pin 4mm × 4mm QFN and thermally enhanced 24-pin TSSOP packages.APPLICATIONSDDR MemorySupports DDR, DDR2, and DDR3 StandardsTracking Supplies

The LTC3619B is a dual monolithic synchronous buck regulator using a constant frequency current mode architecture.The input supply voltage range is 2.5V to 5.5V, making it ideal for Li-Ion and USB powered applications. 100% duty cycle capability provides low dropout operation, extending the run time in battery-operated systems. Low output voltages are supported with the 0.6V feedback reference voltage. Channel 1 and channel 2 can supply 400mA and 800mA output current, respectively.The LTC3619B’s programmable average input current limit is ideal for USB applications and for point-of-load power supplies because the LTC3619B’s limited input current will still allow its output to deliver high peak load currents without collapsing the input supply. When the sum of both channels’ currents exceeds the input current limit, channel 2 is current limited while channel 1 remains regulated. The operating frequency is internally set at 2.25MHz allowing the use of small surface mount inductors. Internal soft-start reduces in-rush current during start-up. The LTC3619B is available in small MSOP and 3mm × 3mm DFN packages. The LTC3619B is also available in a low quiescent current, high efficiency Burst Mode®version, LTC3619.Light Load OperationLTC3619Low Ripple Burst Mode (<20mVpp), IQ< 50μALTC3619BPulse Skip (<5mVpp)ApplicationsHigh Peak Load Current ApplicationsUSB Powered DevicesSupercapacitor ChargingRadio Transmitters and Other Handheld Devices

The LTC3621/LTC3621-2 is a high efficiency 17V, 1A synchronous monolithic step-down regulator. The switching frequency is fixed to 1MHz or 2.25MHz with a ±40% synchronizing range. The regulator features ultralow quiescent current and high efficiencies over a wide VOUTrange.The step-down regulator operates from an input voltage range of 2.7V to 17V and provides an adjustable output range from 0.6V to VINwhile delivering up to 1A of output current. A user-selectable mode input is provided to allow the user to trade off ripple noise for light load efficiency; Burst Mode operation provides the highest efficiency at light loads, while pulse-skipping mode provides the lowest voltage ripple. The MODE pin can also be used to allow the user to sync the switching frequency to an external clock.LTC3621 OptionsPart NameFrequencyVOUTLTC36211.00MHzAdjustableLTC3621-3.31.00MHz3.3VLTC3621-51.00MHz5VLTC3621-22.25MHzAdjustableLTC3621-23.32.25MHz3.3LTC3621-252.25MHz5VAPPLICATIONSPortable-Handheld ScannersIndustrial and Embedded ComputingAutomotive ApplicationsEmergency Radio