LTC3731H Datasheet, PDF (1/32 Pages) Linear Technology – 3-Phase, 600kHz, Synchronous Buck Switching Regulator Controller

LTC3731H
3-Phase, 600kHz,
Synchronous Buck Switching
Regulator Controller
FEATURES
DESCRIPTIO
■ _{3-Phase Current Mode Controller with Onboard}
MOSFET Drivers
■ _{±5% Output Current Matching Optimizes Thermal}
Performance and Size of Inductors and MOSFETs
■ _{±2% VREF Accuracy Over Temperature up to 140°C}
■ _{Reduced Power Supply Induced Noise}
■ _{±10% Power Good Output Indicator}
■ _{250kHz to 600kHz Per Phase, PLL, Fixed Frequency}
■ _{PWM, Stage Shedding}^TM _{or Burst Mode}^® _Operation
■ _OPTI-LOOP^® _{Compensation Minimizes COUT}
■ _{Adjustable Soft-Start Current Ramping}
■ _{Short-Circuit Shutdown Timer with Defeat Option}
■ _{Overvoltage Soft Latch}
■ _{Adjustable Undervoltage Lockout Threshold}
■ _{Selectable Phase Output for Up to 12-Phase Operation}
■ _{Available in 36-Pin Narrow (0.209") SSOP Package}
U
APPLICATIO S
■ _{Automotive and Industrial Power Supplies}
■ _{High Output Current DC/DC Power Supplies}
The LTC^®3731H is a PolyPhase^® synchronous step-down
switching regulator controller that drives all N-channel
external power MOSFET stages in a phase-lockable fixed
frequency architecture. The LTC3731H is rated for opera-
tion up to 140°C junction temperature. The 3-phase con-
troller drives its output stages with 120° phase separation
at frequencies up to 600kHz per phase to minimize the
RMS current losses in both the input and output filter
capacitors. 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 Burst Mode operation.
The precision reference supports output voltages from 0.6V
to 6V. Current foldback provides protection for the exter-
nal MOSFETs under short-circuit or overload conditions.
Please refer to the LTC3731 data sheet for 0°C to 70°C and
–40°C to 85°C rated versions.
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Burst Mode, OPTI-LOOP and PolyPhase are registered trademarks of Linear Technology
Corporation. Stage Shedding is a trademark of Linear Technology Corporation.
Protected by U.S. Patents including 5481178, 5929620, 6177787, 6144194, 6100678,
5408150, 6580258, 6462525, 6304066, 5705919.
TYPICAL APPLICATIO
V_CC
4.5V TO 7V
10µF
0.1µF
SW3 SW2 SW1
POWER GOOD INDICATOR
OPTIONAL SYNC IN
V_CC
TG1
LTC3731H _SW1
BOOST1
BOOST2
BG1
BOOST3
SENSE1⁺
SENSE1^–
TG2
PGOOD
PLLIN
SW2
PLLFLTR
BG2
36k
V_IN
12k
680pF
UVADJ
PGND
SENSE2⁺
SENSE2^–
I_TH
TG3
5k
RUN/SS
SW3
0.01µF
SGND
BG3
EAIN
100pF
7.5k
SENSE3⁺
SENSE3^–
6.04k
0.8µH
0.003Ω
V_IN
+
5V TO 28V
22µF
35V
V_IN
0.8µH
0.003Ω
V_OUT
1.35V
55A
V_IN
0.8µH
0.003Ω
+ C_OUT
470µF
4V
3731H F01
Figure 1. High Current Triple Phase Step-Down Converter
3731hf
1