LTC3811_15 Datasheet, PDF (1/48 Pages) Linear Technology – High Speed Dual, Multiphase Step-Down DC/DC Controller

LTC3811
FEATURES
High Speed Dual,
Multiphase Step-Down DC/DC
DESCRIPTION
Controller
■ _{Fixed Frequency, Peak Current Mode Control}
■ _{±0.5% Output Accuracy Over Temperature}
■ _{Optimized for Low VOUT Applications (Up to 3.3V)}
■ _{Dual or Single Output, Multiphase Operation}
■ _{Wide VIN Range: 4.5V to 30V Operation}
■ _{High Speed Differential Remote Sense Amplifier}
■ _{Inductor DCR or Sense Resistor Capable}
■ _{Adjustable Peak Current Sense Voltage:}
24mV to 85mV
■ _{Very Low Duty Cycle Operation: tON(MIN) = 65ns (Typ)}
■ _{Powerful Internal Gate Drivers}
■ _{Output Voltage Soft-Start, Tracking and Sequencing}
■ _{Programmable Load Line for Reduced COUT}
■ _{Clock Input and Output for Up to 12-Phase Operation}
■ _{Fixed Frequency Operation from 250kHz to 750kHz}
■ _{PLL Synchronization from 150kHz Up to 900kHz}
■ _{Selectable CCM or DCM Operation}
■ _{Available in 5mm × 7mm QFN and G36 Packages}
APPLICATIONS
■ _{Network Servers}
■ _{High Current ASIC Supplies}
■ _{Low Voltage Power Distribution}
The LTC^®3811 is a dual, PolyPhase^® synchronous step-
down switching regulator controller optimized for output
voltages up to 3.3V. The LTC3811 includes high bandwidth
error amplifiers as well as a high speed differential remote
sense amplifier. The sense voltage range is programmable
from 24mV to 85mV, allowing the use of either the inductor
DCR or a discrete sense resistor. Multiphase operation is
made possible using the MODE/SYNC input, the CLKOUT
output and the PHASEMODE control pin, allowing 1-, 2-,
3-, 4-, 6- or 12-phase operation.
Large internal gate drivers minimize switching losses and
allow the use of multiple power MOSFETs connected in
parallel for high current applications.
The operating frequency of the LTC3811 can be programmed
from 250kHz to 750kHz and can also be synchronized to
an external clock using the internal PLL.
Tracking and sequencing are possible with the LTC3811,
and soft-start is programmed with an external capacitor.
Shutdown reduces supply current to 20μA.
, LT, LTC, LTM and PolyPhase are registered trademarks of Linear Technology
Corporation. All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 5481178, 6304066, 5929620, 6177787, 6144194,
6580258, 5705919.
TYPICAL APPLICATION
V_OUT1
2V
15A
Dual Output, 2-Phase Tracking Core and I/O Supply
V_IN
4.5V TO 14V
V_IN
TG1
INTV_CC DRV_CC
TG2
BOOST1
SW1
BG1
BOOST2
SW2
BG2
RUN1
PGND
RUN2
SENSE1⁺
SENSE1^–
RNG1
RNG2
FB1
LTC3811
SENSE2⁺
SENSE2^–
DIFF/IN⁺
DIFF/IN^–
DIFF/OUT
FB2
COMP1
COMP2
SS/TRACK1 SGND SS/TRACK2
V_OUT2
1.5V
15A
3811 TA01a
V_OUT
100mV/DIV
Load Step
I_L
5A/DIV
V_IN = 12V
V_OUT = 2V
I_OUT = 0A to 12.5A
20μs/DIV
3811 TA01b
3811f
1