Date: 12/11/2009
PolyPhase current mode synchronous step-down DC/DC switching regulator from Linear
Linear has introduced the LTC3855, a new dual PolyPhase current mode synchronous step-down DC/DC switching regulator controller that drives all N-channel power MOSFET stages with multiphase operation, differential output voltage sensing and integrated phase-lock loop (PLL) synchronization. It includes a high-speed differential remote sense amplifier. The maximum current sense voltage is programmable for 30mV, 50mV or 75mV, allowing the use of either the inductor DCR or a discrete sense resistor as the sensing element. The LTC3855 is suitable for the applications such as high current ASIC and FPGA supplies, power distribution buses, high power audio amplifiers and network servers.
The LTC3855 features a precision 0.6V reference and can produce output voltages up to 12.5V. A wide 4.5V to 38V input supply range encompasses most intermediate bus voltages and battery chemistries. Operating the two controller output stages out of phase minimizes power loss and supply noise. Burst Mode operation, continuous or pulse-skipping modes are supported.
The key features of the LTC3855 are,
Dual, 180° phased controllers reduce required input capacitance and power supply induced noise
Up to 95% of high efficiency
RSENSE or DCR current sensing
Programmable DCR temperature compensation
Phase-lockable fixed frequency from 250kHz to 770kHz
Remote sensing differential amplifier
Dual N-Channel MOSFET synchronous drive
0.6V to 12.5V of VOUT without differential amplifier
0.6V to 3.3V of VOUT with differential amplifier
Clock input and output for up to 12-phase operation
Adjustable soft-start or VOUT tracking
Foldback output current limiting
Output overvoltage protection
Tracking and sequencing functions allow the optimization of power-up and power-down of multiple power supplies. Additional features include current mode control, an onboard LDO for IC power, programmable soft start, two power good signals and external VCC control.
Operating temperature range:
LTC3855E: -40°C to 85°C
LTC3855I: -40°C to 125°C
Package: 40-Pin (6mm × 6mm) QFN and 38-Lead FE package
Price:
LTC3855E: Starts at each $3.18 for 1k pieces
LTC3855I: Starts at each $3.59 for 1k pieces
Availability: Both versions are available from stock
For more details visit www.linear.com
Editorial Product Rating: Average