LTC3786
Low I Synchronous
Q
Boost Controller
FeaTures
DescripTion
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Synchronous Operation For Highest Efficiency and
The LTC®3786 is a high performance synchronous boost
converter controller that drives all N-channel power
MOSFETs. Synchronous rectification increases efficiency,
reduces power losses and eases thermal requirements,
allowing the LTC3786 to be used in high power boost
applications.
Reduced Heat Dissipation
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Wide V Range: 4.5V to 38V (40V Abs Max) and
IN
Operates Down to 2.5V After Start-Up
Output Voltages Up to 60V
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1ꢀ 1.2V Reference Voltage
R
or Inductor DCR Current Sensing
SENSE
A 4.5V to 38V 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 LTC3786 can operate from
an input supply as low as 2.5V after start-up. The 55µA
no-load quiescent current extends operating run time in
battery-powered systems.
100ꢀ DutyCycle Capability forSynchronous MOSFET
Low Quiescent Current: 55µA
Phase-Lockable Frequency (75kHz to 850kHz)
Programmable Fixed Frequency (50kHz to 900kHz)
Adjustable Output Voltage Soft-Start
Power Good Output Voltage Monitor
Low Shutdown Current I : <8µA
Internal 5.4V LDO for Gate Drive Supply
Thermally Enhanced 16-Pin 3mm × 3mm QFN and
MSOP Packages
Q
The operating frequency can be set for a 50kHz to 900kHz
range or synchronized to an external clock using the
internal PLL. The LTC3786 also features a precision 1.2V
reference and a power good output indicator. The SS pin
rampstheoutputvoltageduringstart-up.ThePLLIN/MODE
pin selects among Burst Mode® operation, pulse-skipping
mode or continuous inductor current mode at light loads.
applicaTions
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Industrial and Automotive Power Supplies
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Automotive Start-Stop Systems
L, LT, LTC, LTM, Burst Mode, OPTI-LOOP, Linear Technology and the Linear logo are
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Medical Devices
High Voltage Battery-Powered Systems
registered trademarks and No R
is a trademark of Linear Technology Corporation. All other
SENSE
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trademarks are the property of their respective owners. Protected by U. S. Patents, including
5408150, 5481178, 5705919, 5929620, 6177787, 6498466, 6580258, 6611131.
Typical applicaTion
12V to 24V/5A Synchronous Boost Converter
Efficiency and Power Loss
vs Load Current
V
4.5V TO 24V
IN
VBIAS
SENSE
100
90
80
70
60
50
40
30
20
10
0
10000
1000
100
10
+
LTC3786
220µF
4mΩ
BURST
–
EFFICIENCY
SENSE
BURST
LOSS
PGOOD
PLLIN/MODE
RUN
3.3µH
FREQ
TG
0.1µF
V
24V
5A
OUT
SS
SW
0.1µF
15nF
220µF
8.66k
12.1k
BOOST
BG
ITH
V
V
= 12V
220pF
IN
OUT
1
= 24V
Burst Mode OPERATION
FIGURE 8 CIRCUIT
INTV
CC
VFB
0.1
4.7µF
0.00001 0.0001 0.001 0.01
0.1
1
10
GND
232k
OUTPUT CURRENT (A)
3786 TA01a
3786 TA01b
3786fa
1