2-Phase Synchronous Step-Down DC/DC Controller with Diffamp

The LTC3856 is a single output, dual channel PolyPhase synchronous step-down DC/DC controller that drives all N-channel power MOSFET stages. This device includes a high speed differential amplifier for remote output voltage sense. Power loss and supply noise are minimized by operating the two controller output stages out-of-phase and up to 12-phase operation can be achieved.

The LTC3856 monitors the output current by sensing the voltage drop across the output inductor (DCR) or by using a sense resistor. DCR temperature compensation maintains an accurate current sense threshold over a broad temperature range. A constant-frequency, current mode architecture allows a phase-lockable frequency of up to 770kHz.

A wide 4.5V to 38V input supply range encompasses most intermediate bus voltages and battery chemistries. Burst Mode operation, continuous or Stage Shedding modes are supported. A TK/SS pin shared by both channels ramps the output voltage during start-up.

Applications

* Telecom and Datacom Systems

* Industrial and Medical Instruments

* DC Power Distribution Systems

* Computer Systems

* PolyPhase® Controller Reduces Input and Output Capacitance and Power Supply Induced Noise

* Wide VIN Range: 4.5V to 38V Operation

* ±0.75%, 0.6V Reference Voltage Accuracy

* High Efficiency: Up to 95%

* Programmable Burst Mode® Operation or Stage Shedding™ for Highest Light Load Efficiency

* Active Voltage Positioning (AVP)

* RSENSE or DCR Current Sensing

* Programmable DCR Temperature Compensation

* Phase-Lockable Fixed Frequency: 250kHz to 770kHz

* True Remote Sense Differential Amplifier

* Dual N-Channel MOSFET Synchronous Drive

* VOUT Range: 0.6V to 5V without Differential Amplifier

* VOUT Range: 0.6V to 3.3V with Differential Amplifier

* Adjustable Soft-Start or VOUT Tracking

* Stackable for Up to 12-Phase Operation

* 32-Pin (5mm × 5mm) QFN and 38-Pin TSSOP Packages