LTC3788-1 Datasheet, PDF (1/28 Pages) Linear Technology – 2-Phase, Dual Output Synchronous Boost Controller

LTC3788-1
2-Phase, Dual Output
Synchronous Boost Controller
FEATURES
DESCRIPTION
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 _{Adjustable Output Voltage Soft-Start}
n _{Power Good Output Voltage Monitor}
n _{Low Shutdown Current IQ: < 8μA}
n _{Internal LDO Powers Gate Drive from VBIAS or EXTVCC}
n _{Available in a Narrow SSOP Package}
APPLICATIONS
n _Industrial
n _Automotive
n _Medical
n _Military
The LTC^®3788-1 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 LTC3788-1 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 LTC3788-1 features a precision 1.2V reference and a
power good output indicator. 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 leadless 32-pin QFN package with additional features
of adjustable current limit, clock out, phase modulation
and two PGOOD outputs, see the LTC3788 data sheet.
L, LT, LTC, LTM, Linear Technology, OPTI-LOOP, Burst Mode 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
LTC3788-1
BG1
BG2
0.1μF
3.3μH
V_OUT
24V AT 3A
SENSE1⁺
SENSE2⁺
SENSE1^–
SENSE2^–
RUN1
PGND
15nF
2.7k
VFB1
PGOOD1
FREQ
PLLIN/MODE
RUN2
VFB2
EXTV_CC
ITH1 SS1 SGND SS2 ITH2
100pF
0.1μF
0.1μF
232k
15nF
220pF _{8.66k 12.1k}
220μF
37881 TA01a
Efficiency and Power Loss
vs Load 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)
37881 TA01b
37881f
1