Dual, 2-Phase Synchronous Step-Down DC/DC Controllers

The LTC3869 is a high performance dual synchronous step-down switching regulator controller that drives all N-channel synchronous power MOSFET stages. A constant frequency current mode architecture allows a phase-lockable frequency of up to 780kHz. Power loss and noise due to the ESR of the input capacitors are minimized by operating the two controller output stages out-of-phase.

OPTI-LOOP® compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. A wide 4V to 38V input supply range encompasses most battery chemistries. Independent TK/SS pins for each controller ramp the output voltage during start-up. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The MODE/PLLIN pin selects among Burst Mode® operation, pulse-skipping mode, or continuous inductor current mode and allows the IC to be synchronized to an external clock.

The LTC3869 is available in low profile 4mm × 4mm and 4mm × 5mm QFN packages. The LTC3869-2 is available in an SSOP-28 package. The LTC3869 is pin-compatible with the LTC3850.

Applications

* Server Systems

* Telecom Systems

* Industrial and Medical Instruments

* High Power Battery-Operated Devices

* DC Power Distribution Systems

* Dual, 180° Phased Controllers Reduce Required Input Capacitance and Power Supply Induced Noise

* Accurate Multiphase Current Matching

* RSENSE or DCR Current Sensing

* ±0.75% 0.6V Output Voltage Accuracy

* Phase-Lockable Fixed Frequency 250kHz to 780kHz

* High Efficiency: Up to 95%

* Dual N-channel MOSFET Synchronous Drive

* Wide VIN Range: 4V to 38V (40V Max) Operation

* Wide VOUT Range: 0.6V to 12.5V Operation

* Adjustable Soft-Start Current Ramping or Tracking

* Foldback Output Current Limiting

* Output Overvoltage Protection

* Power Good Output Voltage Monitor

* 5V Low Dropout Regulator

* Small 28-Lead QFN and Narrow SSOP Packages