LTC3788_15 Datasheet, PDF (1/32 Pages) Linear Technology – 2-Phase, Dual Output Synchronous Boost Controller

LTC3788
2-Phase, Dual Output
Synchronous Boost Controller
Features
n _{Synchronous Operation for Highest Efficiency and}
Reduced Heat Dissipation
n _{Wide Input Range: 4.5V to 38V (40V Abs Max) and}
Operates Down to 2.5V After Start-Up
n _{Output Voltages Up to 60V}
n _{±1% 1.2V Reference Voltage}
n _{RSENSE or Inductor DCR Current Sensing}
n _{100% Duty Cycle Capability for Synchronous MOSFET}
n _{Low Quiescent Current: 125µA}
n _{Phase-Lockable Frequency (75kHz to 850kHz)}
n _{Programmable Fixed Frequency (50kHz to 900kHz)}
n _{Selectable Current Limit}
n _{Adjustable Output Voltage Soft-Start}
n _{Power Good Output Voltage Monitors}
n _{Low Shutdown Current IQ: < 8μA}
n _{Internal LDO Powers Gate Drive from VBIAS or EXTVCC}
n _{Thermally Enhanced Low Profile 32-Pin 5mm × 5mm}
QFN Package
Applications
n _Industrial
n _Automotive
n _Medical
n _Military
Description
The LTC^®3788 is a high performance 2-phase dual
synchronous boost converter controller that drives all
N-channel power MOSFETs. Synchronous rectification
increases efficiency, reduces power losses and eases
thermal requirements, allowing the LTC3788 to be used
in high power boost applications.
A constant-frequency current mode architecture allows a
phase-lockable frequency of up to 850kHz. OPTI-LOOP^®
compensation allows the transient response to be optimized
over a wide range of output capacitance and ESR values.
The LTC3788 features a precision 1.2V reference and dual
power good output indicators. A 4.5V to 38V input supply
range encompasses a wide range of system architectures
and battery chemistries.
Independent SS pins for each controller ramp the output
voltages during start-up. The PLLIN/MODE pin selects
among Burst Mode^® operation, pulse-skipping mode or
continuous inductor current mode at light loads.
For a leaded 28-lead SSOP package with a fixed current
limit and one PGOOD output, without phase modulation
or a clock output, see the LTC3788-1 data sheet.
L, LT, LTC, LTM, Linear Technology, Burst Mode, OPTI-LOOP, PolyPhase and the Linear logo
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
V_IN 4.5V TO 12V START-UP VOLTAGE
OPERATES THROUGH TRANSIENTS DOWN TO 2.5V
V_IN
V_OUT
12V AT 5A
3mΩ
1.25µH
110k
220µF
12.1k
4.7µF
4.7µF
4mΩ
220µF
TG1 VBIAS INTV_CC TG2
0.1µF
BOOST1
BOOST2
SW1
SW2
BG1
LTC3788
BG2
0.1µF
SENSE1⁺
SENSE1^–
SENSE2⁺
SENSE2^–
PGND
15nF
2.7k
VFB1
VFB2
FREQ
PLLIN/MODE
ITH1 SS1 SGND SS2 ITH2
100pF
0.1µF
0.1µF
220pF
3.3µH
V_OUT
24V AT 3A
232k
15nF
8.66k 12.1k
3788 TA01a
220µF
Efficiency and Power Loss
vs Output Current
100
10000
90
80
1000
70
60
100
50
40
10
30
20
10
0
0.00001 0.0001 0.001
V_IN = 12V
1
V_OUT = 24V
Burst Mode OPERATION
FIGURE 9 CIRCUIT
0.1
0.01 0.1 1 10
OUTPUT CURRENT (A)
3788 TA01b
3788fc
1