LTC3738 Datasheet, PDF (1/32 Pages) Linear Technology – 3-Phase Buck Controller for Intel VRM9/VRM10 with Active Voltage Positioning

FEATURES
■ _{3-Phase Controller with Onboard MOSFET Drivers}
■ _{Programmable Active Voltage Positioning (AVP)}
with True Current Sensing
■ _{Programmable External Thermal Detection or}
Internal Thermal Sensing
■ _{Precise Output Current Matching Optimizes}
Thermal Performance and Solution Size
■ _{Supports Starting into Precharged VOUTS}
■ _{Differential Amplifier Accurately Senses VOUT}
■ _{PWM, Pulse Skip and Stage Shedding}^TM _Operation
■ _{Synchronizable}
■ _{210kHz to 530kHz Per Phase, Fixed Frequency}
■ _{Output Power Good Indicator with Adaptive Blanking}
■ _{Adjustable Soft-Start Current Ramping}
■ _{Short-Circuit Shutdown Timer with Defeat Option}
■ _OPTI-LOOP^® _{Compensation Minimizes COUT}
■ _{38-Lead (5mm × 7mm) QFN Package}
U
APPLICATIO S
■ _{High Performance Notebook Computers}
■ _{Servers, Desktop Computers and Workstations}
U.S. Patent Numbers: 5481178, 5994885, 5929620, 6177787, 6144194, 6580258, 6462525,
6593724, 6674274, 6100678 pending on AVP technique.
LTC3738
3-Phase Buck Controller
for Intel VRM9/VRM10 with
Active Voltage Positioning
DESCRIPTIO
The LTC^®3738 is a 3-phase synchronous step-down switch-
ing regulator controller that drives all N-channel external
power MOSFET stages in a phase-lockable, fixed fre-
quency architecture. The 3-phase technique effectively
triples the fundamental frequency, improving transient
response while operating each controller at an optimal
frequency for efficiency and ease of thermal design. Light
load efficiency is optimized by using a choice of output
Stage Shedding or Pulse Skip mode technology.
The LTC3738 also allows users to program load slope via
a resistor for AVP control. Both external and internal
thermal sensing are available from the on-chip thermal
detector and comparator.
A differential amplifier provides sensing of both the high
and low sides of the output voltage.
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 a 1µs timeout.
, LTC and LT are registered trademarks of Linear Technology Corporation.
OPTI-LOOP is a registered trademark of Linear Technology Corporation.
Stage Shedding is a trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
VRM10 Step-Down Controller
5V
10µF
0.1µF
SW3 SW2 SW1
POWER GOOD INDICATOR
MODE SELECTION/SYNC IN
THERMAL INPUT
VR HOT INDICATOR
ON/OFF
680pF
5k
0.1µF
100pF
V_CC
TG1
LTC3738 _SW1
BOOST1
BOOST2
BG1
BOOST3
SENSE1⁺
SENSE1^–
PGOOD
FCB/SYNC
PLLFLTR
TSNS
VR_HOTB
OUTEN
TG2
SW2
BG2
PGND
SENSE2⁺
SENSE2^–
I_TH
SS
SGND
EAIN
AVP
IN⁺
IN^–
TG3
SW3
BG3
SENSE3⁺
SENSE3^–
VID0-VID5
0.8µH
0.002Ω
V_IN
0.8µH
0.002Ω
V_IN
0.8µH
0.002Ω
6 VID BITS
V_IN
+
5V TO 28V
22µF
×2
V_OUT
0.8375V TO 1.6000V
+ _470µF
×4
3738 TA01
3738f
1