POWER LOSS (mW)
LTC3784
60V PolyPhase Synchronous
Boost Controller
Fea T Descrip T
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PolyPhase Operation Reduces Required Input and The LTC 3784 is a high performance PolyPhase single
Output Capacitance and Power Supply Induced Noise output synchronous boost converter controller that drives
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Synchronous Operation for Highest Efficiency and two N-channel power MOSFET stages out-of-phase.
Reduced Heat Dissipation Multiphase operation reduces input and output capacitor
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Wide V Range: 4.5V to 60V (65V Abs Max); requirements and allows the use of smaller inductors than
IN
Operates Down to 2.3V After Start-Up the single-phase equivalent. Synchronous rectification in-
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Output Voltage Up to 60V creases efficiency, reduces power losses and eases thermal
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1% 1.200V Reference Voltage requirements, simplifying high power boost applications.
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R or Inductor DCR Current Sensing
SENSE
A 4.5V to 60V input supply range encompasses a wide
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100% Duty Cycle Capability for Synchronous MOSFET
range of system architectures and battery chemistries.
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Low Quiescent Current: 28A
When biased from the output of the boost converter or
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Phase-Lockable Frequency (75kHz to 850kHz)
another auxiliary supply, the LTC3784 can operate from an
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Programmable Fixed Frequency (50kHz to 900kHz)
input supply as low as 2.3V after start-up. The operating
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Power Good Output Voltage Monitor
frequency can be set within a 50kHz to 900kHz range or
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Low Shutdown Current, I < 4A
Q
synchronized to an external clock using the internal PLL.
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Internal LDO Powers Gate Drive from VBIAS or EXTV
CC
PolyPhase operation allows the LTC3784 to be configured
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Thermally Enhanced Low Profile 28-Pin 4mm 5mm
for 2-, 3-, 4-, 6- and 12-phase operation.
QFN Package and Narrow SSOP Package
The SS pin ramps the output voltage during start-up. The
a T
operation, pulse-
PLLIN/MODE pin selects Burst Mode
skipping mode or forced continuous mode at light loads.
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Industrial
L, LT, LTC, LTM, Linear Technology, the Linear logo, Burst Mode, OPTI-LOOP and PolyPhase
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Automotive
are registered trademarks and No R and ThinSOT are trademarks of Linear Technology
SENSE
Corporation. All other trademarks are the property of their respective owners. Protected by
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Medical
U. S. Patents, including 5408150, 5481178, 5705919, 5929620, 6144194, 6177787, 6580258.
n
Military
Typical a T
240W, 12V to 24V/10A 2-Phase Synchronous Boost Converter
3.3H
4m
+
SENSE1
47F
Efficiency and Power Loss
SENSE1
vs Output Current
BG1
BOOST1
100 10000
0.1F
V V
IN VBIAS OUT
24V AT 10A
90
4.5V TO 60V
SW1
DOWN TO 2.3V AFTER
220F
80 1000
TG1
STARTUP IF VBIAS IS
LTC3784
POWERED FROM V
OUT
70
INTV
CC
V 60 100
OUT
4.7F 3.3H
4m
FOLLOWS V
IN
50
FOR V > 24V
IN
+
SENSE2
40 10
BURST EFFICIENCY
SENSE2
30 BURST LOSS
BG2
V = 12V
IN
20 1
V = 24V
OUT
BOOST2
Burst Mode OPERATION
10
FREQ 0.1F
FIGURE 10 CIRCUIT
0 0.1
OVMODE SW2
0.00001 0.0001 0.001 0.01 0.1 1 10
TG2
PLLIN/MODE
ITH VFB OUTPUT CURRENT (A) 3784 TA01b
3784 TA01a
SS SGND PGND
15nF 232k
12.1k
8.66k 100pF 0.1F
3784fb
1
For more information www.linear.com/LTC3784
EFFICIENCY (%)
ion pplica
ions pplica
ion uresLTC3784
(Notes 1, 3)
a Te Maxi Mu M r a T
VBIAS ........................................................ 0.3V to 65V EXTV ...................................................... 0.3V to 14V
CC
+ +
BOOST1 and BOOST2 .................................0.3V to 71V SENSE1 , SENSE1 , SENSE2 , SENSE2 ... 0.3V to 65V
+ +
SW1 and SW2 ............................................... 5V to 65V (SENSE1 - SENSE1 ), (SENSE2 - SENSE2 ) ...0.3V to 0.3V
RUN ............................................................. 0.3V to 8V ILIM, SS, ITH, FREQ, PHASMD, VFB .....0.3V to INTV
CC
Maximum Current Sourced into Pin Operating Junction Temperature
From Source >8V ..............................................100A Range (Note 2) ........................................55C to 150C
PGOOD, PLLIN/MODE ................................. 0.3V to 6V Storage Temperature Range .................. 65C to 150C
INTV , (BOOST1 - SW1), (BOOST2 - SW2) ...0.3V to 6V Lead Temperature (Soldering, 10 sec) SSOP ........300C
CC
p in c F T
TOP VIEW
TOP VIEW
1 28 PGOOD
ILIM
+
2 27 SW1
SENSE1
28 27 26 25 24 23
3 26 TG1
SENSE1
FREQ 1 22 BOOST1
4 25 BOOST1
FREQ
2 21 BG1
PHASMD
5 24 BG1
PHASMD
3 20 VBIAS
CLKOUT
6 23 VBIAS
CLKOUT
4 19
PGND
PLLIN/MODE 29
7 22 PGND
PLLIN/MODE
GND
5 18 EXTV
SGND CC
8 21 EXTV
SGND
CC
6 17 INTV
RUN CC
9 20 INTV
RUN
CC
7 16 BG2
SS
10 19 BG2
SS
8 15 BOOST2
SENSE2
11 18 BOOST2
SENSE2
9 10 11 12 13 14
+
12 17 TG2
SENSE2
13 16 SW2
VFB
14 15 OVMODE
ITH
UFD PACKAGE
28-LEAD (4mm 5mm) PLASTIC QFN
GN PACKAGE
28-LEAD PLASTIC SSOP T = 150C, = 43C/W
JMAX JA
EXPOSED PAD (PIN 29) IS GND, MUST BE CONNECTED TO GND
T = 150C, = 80C/W
JMAX JA
o r Der i n F Ma T
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3784EUFD#PBF LTC3784EUFD#TRPBF 3784 28-Lead (4mm 5mm) Plastic QFN 40C to 125C
LTC3784IUFD#PBF LTC3784IUFD#TRPBF 3784 28-Lead (4mm 5mm) Plastic QFN 40C to 125C
LTC3784HUFD#PBF LTC3784HUFD#TRPBF 3784 28-Lead (4mm 5mm) Plastic QFN 40C to 150C
LTC3784MPUFD#PBF LTC3784MPUFD#TRPBF 3784 55C to 150C
28-Lead (4mm 5mm) Plastic QFN
LTC3784EGN#PBF LTC3784EGN#TRPBF LTC3784GN 28-Lead Plastic SSOP 40C to 125C
LTC3784IGN#PBF LTC3784IGN#TRPBF LTC3784GN 28-Lead Plastic SSOP 40C to 125C
LTC3784HGN#PBF LTC3784HGN#TRPBF LTC3784GN 28-Lead Plastic SSOP 40C to 150C
LTC3784MPGN#PBF LTC3784MPGN#TRPBF LTC3784GN 28-Lead Plastic SSOP 55C to 150C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to: