LTC3733_15 Datasheet, PDF (1/32 Pages) Linear Technology – 3-Phase, Buck Controllers for AMD CPUs

LTC3733/LTC3733-1
3-Phase, Buck
Controllers for AMD CPUs
FEATURES
s _{3-Phase Controller with Onboard MOSFET Drivers}
s _{Current Mode Control Ensures Current Sharing}
s _{Differential Amplifier Accurately Senses VOUT}
s _{±5% Output Current Matching Optimizes Thermal}
Performance and Size of Inductors and MOSFETs
s _{Reduced Input and Output Capacitance}
s _{Supports Active Voltage Positioning}
s _{VID Programmable Output Voltage from 0.8V to 1.55V}
(AMD Opteron^TM CPU)
s _{6-Phase, 90A to 120A Operation}
s _{Output Power Good Indicator with Adaptive Blanking}
s _{210kHz to 530kHz Per Phase, PLL, Fixed Frequency}
s _{Synchronizable (LTC3733-1)}
s _{PWM, Stage Shedding or Burst Mode}^® _Operation
s _OPTI-LOOP^® _{Compensation Minimizes COUT}
s _{Adjustable Soft-Start Current Ramping}
s _{Short-Circuit Shutdown Timer with Defeat Option}
s _{No_CPU Detection}
s _{36-Lead 0.209" SSOP and 38-Lead (5mm × 7mm) QFN}
U
APPLICATIO S
s _{High Performance Notebook Computers}
s _{Servers, Desktop Computers and Workstations}
DESCRIPTIO
The LTC^®3733 family are PolyPhase^® synchronous step-
down switching regulator controllers that drive all
N-channel external power MOSFET stages in a phase-
lockable, fixed frequency architecture. The 3-phase con-
troller drives its output stages with 120° phase separation
at frequencies of up to 530kHz per phase to minimize the
RMS current dissipated by the ESR of both the input and
output filter capacitors. The 3-phase technique effectively
triples the fundamental frequency, improving transient
response while operating each phase at an optimal fre-
quency for efficiency and ease of thermal design. Light
load efficiency is optimized by using a choice of output
stage shedding or Burst Mode technology.
A differential amplifier provides true remote sensing of both
the high and low sides of the output voltage at load points.
Soft-start and a defeatable, timed short-circuit shutdown
protect the MOSFETs and the load. A foldback current
circuit also provides protection for the external MOSFETs
under short-circuit or overload conditions. An all-“1” VID
detector turns off the regulator after 1µs timeout.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode, OPTI-LOOP and PolyPhase are registered trademarks of Linear Technology
Corporation. AMD Opteron is a trademark of Advanced Micro Devices, Inc.
TYPICAL APPLICATIO
5V
10µF
0.1µF
SW3 SW2 SW1
POWER GOOD INDICATOR
OPTIONAL SYN IN
5 VID BITS
ON/OFF
680pF
5k
0.1µF
100pF
V_CC
TG1
LTC3733-1 _SW1
BOOST1
BOOST2
BG1
BOOST3
SENSE1⁺
SENSE1^–
PGOOD
PLLIN
PLLFLTR
VID0-VID4
RUN
I_TH
SS
SGND
EAIN
IN^–
IN⁺
TG2
SW2
BG2
PGND
SENSE2⁺
SENSE2^–
TG3
SW3
BG3
SENSE3⁺
SENSE3^–
L1 0.8µH
D1
0.002Ω
V_IN
+
5V TO 28V
22µF
35V
×2
V_IN
L2 0.8µH
0.002Ω
D2
V_OUT
0.8V TO 1.55V
65A
V_IN
L3 0.8µH
0.002Ω
D3
+
C_OUT
470µF
4V
×4
3733 F01
Figure 1. High Current Triple Phase Step-Down Converter
3733f
1