LTC3785 Datasheet, PDF (1/20 Pages) Linear Technology – 10V, High Effi ciency, Synchronous, No RSENSE Buck-Boost Controller

FEATURES
■ _{Single Inductor Architecture Allows VIN Above,}
Below or Equal to V_OUT
■ _{2.7V to 10V Input and Output Range}
■ _{Up to 96% Efficiency}
■ _{Up to 10A of Output Current}
■ _{All N-Channel MOSFETs, No RSENSE}
■ _{True Output Disconnect During Shutdown}
■ _{Programmable Current Limit and Soft-Start}
■ _{Optional Short-Circuit Shutdown Timer}
■ _{Output Overvoltage and Undervoltage Protection}
■ _{Programmable Frequency: 100kHz to 1MHz}
■ _{Selectable Burst Mode}^® _Operation
■ _{Available in 24-Lead (4mm × 4mm) Exposed Pad}
QFN Package
U
APPLICATIO S
■ _{Palmtop Computers}
■ _{Handheld Instruments}
■ _{Wireless Modems}
■ _{Cellular Telephones}
TYPICAL APPLICATIO
V_OUT
V_IN
V_SENSE
V_CC
I_SVIN
TG1
V_BST1
FB
SW1
I_SSW1
V_DRV
BG1
LTC3785
V_C
RT
MODE
I_SVOUT
TG2
4.7µF
V_IN
2.7V
TO 10V
22µF
4.7µH
V_OUT
3.3V
5A
V_BST2
RUN/SS
I_LSET
SW2
I_SSW2
CCM
BG2
GND
100µF
3785 TA01a
LTC3785
10V, High Efficiency,
Synchronous, No R_SENSE^TM
Buck-Boost Controller
DESCRIPTIO
The LTC^®3785 is a high power synchronous buck-boost
controller that drives all N-channel power MOSFETs from
input voltages above, below and equal to the output volt-
age. With an input range of 2.7V to 10V, the LTC3785 is
well suited for a wide variety of single or dual cell Li-Ion
or multi-cell alkaline/NiMH applications.
The operating frequency can be programmed from
100kHz to 1MHz. The soft-start time and current limit are
also programmable. The soft-start capacitor doubles as
the fault timer which can program the IC to latch off or
recycle after a determined off time. Burst Mode opera-
tion is user controlled and can be enabled by driving the
MODE pin high.
Protection features include foldback current limit, short-
circuit and overvoltage protection.
, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology
Corporation. No R_SENSE is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Efficiency vs Input Voltage
100
V_OUT = 3.3V
F_OSC = 500kHz
95
I_LOAD = 2A
I_LOAD = 1A
90
85
2.5
4
5.5
7
8.5
10
V_IN (V)
3785 TA01b
3785f
1