LTC3789 Datasheet, PDF (1/28 Pages) Linear Technology – High Efficiency, Synchronous, 4-Switch Buck-Boost Controller

LTC3789
High Efficiency, Synchronous,
4-Switch Buck-Boost Controller
Features
Description
n _{Single Inductor Architecture Allows VIN Above,}
Below or Equal to Regulated V_OUT
n _{Programmable Input or Output Current Feedback Loop}
n _{Wide VIN Range: 4V to 38V}
n _{1% Output Voltage Accuracy: 0.8V < VOUT < 38V}
n _{Synchronous Rectification: Up to 98% Efficiency}
n _{Current Mode Control}
n _{Phase-Lockable Fixed Frequency: 200kHz to 600kHz}
n _{No Reverse Current During Start-Up}
n _{Power Good Output Voltage Monitor}
n _{Internal 5.5V LDO}
n _{Quad N-Channel MOSFET Synchronous Drive}
n _{VOUT Disconnected from VIN During Shutdown}
n _{Adjustable Soft-Start Output Ramping}
n _{Available in 28-Lead QFN (4mm × 5mm) and}
28-Lead SSOP Packages
Applications
n _{Automotive Systems}
n _{Distributed DC Power Systems}
n _{High Power Battery-Operated Devices}
n _{Industrial Control}
The LTC^®3789 is a high performance buck-boost switch-
ing regulator controller that operates from input volt-
ages above, below or equal to the output voltage. The
constant-frequency, current mode architecture allows a
phase-lockable frequency of up to 600kHz, while an output
current feedback loop provides support for battery charg-
ing. With a wide 4V to 38V (40V maximum) input and
output range and seamless, low noise transitions between
operating regions, the LTC3789 is ideal for automotive,
telecom and battery-powered systems.
The operating mode of the controller is determined through
the MODE/PLLIN pin. The MODE/PLLIN pin can select
between pulse-skipping mode and forced continuous
mode operation and allows the IC to be synchronized to
an external clock. Pulse-skipping mode offers the lowest
ripple at light loads, while forced continuous mode operates
at a constant frequency for noise-sensitive applications.
A power good output pin indicates when the output is
within 10% of its designed set point. The LTC3789 is avail-
able in low profile 28-pin 4mm × 5mm QFN and narrow
SSOP packages.
L, LT, LTC, LTM, Linear Technology, the Linear logo, µModule and Burst Mode are registered
trademarks and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks
are the property of their respective owners. Protected by U.S. Patents, including 5408150,
5481178, 5929620, 6580258, 7365525, 7394231.
Typical Application
V_IN
4V TO
38V
22µF
50V
CER A
B
+
4.7µF
0.1µF
I_LIM INTV_CC I_OSENSE–
PGOOD
I_OSENSE+
V_IN
EXTV_CC
V_INSNS
V_OUTSNS
TG1 _LTC3789 TG2
BOOST1
BOOST2
SW1
SW2
BG1
BG2
1000pF
2200pF
8k
0.01µF
I_TH
MODE/PLLIN
SS
RUN
SGND
V_FB
FREQ
SENSE⁺ SENSE^– PGND
1µF
CER
D
0.1µF
C
ON/OFF ^105k
1%
7.5k
121k 1%
0.010Ω
4.7µH
0.010Ω
10µF
+
16V
CER
V_OUT
12V
5A
330µF
16V
3789 TA01
Efficiency and Power Loss
100
12
95
10
90
8
85
6
80
4
75
70
0
2
V_OUT = 12V
I_LOAD = 5A
0
5 10 15 20 25 30 35 40
VIN (V)
3789 TA01b
3789f
1