LTC3784_15 Datasheet, PDF (1/38 Pages) Linear Technology – 60V PolyPhase Synchronous Boost Controller

LTC3784
Features
60V PolyPhase Synchronous
Boost Controller
Description
n _PolyPhase^® _{Operation Reduces Required Input and}
Output Capacitance and Power Supply Induced Noise
n _{Synchronous Operation for Highest Efficiency and}
Reduced Heat Dissipation
n _{Wide VIN Range: 4.5V to 60V (65V Abs Max);}
Operates Down to 2.3V After Start-Up
n _{Output Voltage Up to 60V}
n _{±1% 1.200V Reference Voltage}
n _{RSENSE or Inductor DCR Current Sensing}
n _{100% Duty Cycle Capability for Synchronous MOSFET}
n _{Low Quiescent Current: 28μA}
n _{Phase-Lockable Frequency (75kHz to 850kHz)}
n _{Programmable Fixed Frequency (50kHz to 900kHz)}
n _{Power Good Output Voltage Monitor}
n _{Low Shutdown Current, IQ < 4µA}
n _{Internal LDO Powers Gate Drive from VBIAS or EXTVCC}
n _{Thermally Enhanced Low Profile 28-Pin 4mm × 5mm}
QFN Package and Narrow SSOP Package
Applications
n _Industrial
n _Automotive
n _Medical
n _Military
The LTC^®3784 is a high performance PolyPhase^® single
output synchronous boost converter controller that drives
two N-channel power MOSFET stages out-of-phase.
Multiphase operation reduces input and output capacitor
requirements and allows the use of smaller inductors than
the single-phase equivalent. Synchronous rectification in-
creases efficiency, reduces power losses and eases thermal
requirements, simplifying high power boost applications.
A 4.5V to 60V input supply range encompasses a wide
range of system architectures and battery chemistries.
When biased from the output of the boost converter or
another auxiliary supply, the LTC3784 can operate from an
input supply as low as 2.3V after start-up. The operating
frequency can be set within a 50kHz to 900kHz range or
synchronized to an external clock using the internal PLL.
PolyPhase operation allows the LTC3784 to be configured
for 2-, 3-, 4-, 6- and 12-phase operation.
The SS pin ramps the output voltage during start-up. The
PLLIN/MODE pin selects Burst Mode^® operation, pulse-
skipping mode or forced continuous mode at light loads.
L, LT, LTC, LTM, Linear Technology, the Linear logo, Burst Mode, OPTI-LOOP and PolyPhase
are registered trademarks and No R_SENSE and ThinSOT are trademarks of Linear Technology
Corporation. All other trademarks are the property of their respective owners. Protected by
U. S. Patents, including 5408150, 5481178, 5705919, 5929620, 6144194, 6177787, 6580258.
Typical Application
240W, 12V to 24V/10A 2-Phase Synchronous Boost Converter
4mΩ ^3.3µH
47µF
V_IN
4.5V TO 60V
DOWN TO 2.3V AFTER
STARTUP IF VBIAS IS
POWERED FROM V_OUT
VBIAS
SENSE1⁺
SENSE1^–
BG1
BOOST1
SW1
LTC3784
TG1
INTV_CC
0.1µF
4.7µF
SENSE2⁺
SENSE2^–
BG2
4mΩ ^3.3µH
V_OUT
24V AT 10A
220µF
V_OUT
FOLLOWS V_IN
FOR V_IN > 24V
15nF
8.66k
BOOST2
FREQ
OVMODE
SW2
PLLIN/MODE
TG2
ITH
VFB
SS
SGND PGND
100pF
0.1µF
0.1µF
232k
12.1k
3784 TA01a
Efficiency and Power Loss
vs Output Current
100
10000
90
80
1000
70
60
100
50
40
10
BURST EFFICIENCY
30
BURST LOSS
20
V_IN = 12V
V_OUT = 24V
1
10
Burst Mode OPERATION
FIGURE 10 CIRCUIT
0
0.1
0.00001 0.0001 0.001 0.01 0.1 1 10
OUTPUT CURRENT (A)
3784 TA01b
For more information www.linear.com/LTC3784
3784fb
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