Dual, 2-Phase Synchronous Step-Down Switching Controller

The LTC3850 is a high performance dual synchronous step-down switching regulator controller that drives all N-channel power MOSFET stages. A constant-frequency current mode architecture allows a phase-lockable frequency of up to 780kHz. Power loss and supply noise 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. The LTC3850 features a precision 0.8V reference and a power good output indicator. A wide 4V to 24V (28V maximum/30V for LTC3850I) input supply range encompasses most battery chemistries and intermediate bus voltages.

Independent TK/SS pins for each controller ramp the output voltages 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 LTC3850 is available in low profile 28-pin 4mm × 4mm, 4mm × 5mm QFN and narrow SSOP packages.

Features

LTC3850

SSOP-28 and QFN-28 Packages

LTC3850-1

ILIM function replaced with an EXTVCC function, SSOP-28 package only

LTC3850-2

The LTC3850-2 is identical to the LTC3850-1 SSOP-28, except they have different pin-outs

Applications

* Notebook and Palmtop Computers

* Portable Instruments

* Battery-Operated Digital Devices

* DC Power Distribution Systems

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

* High Efficiency: Up to 95%

* RSENSE or DCR Current Sensing

* ±1% 0.8V Output Voltage Accuracy

* Phase-Lockable Fixed Frequency 250kHz to 780kHz

* Supports Pre-Biased Output