LTC3785-1 Datasheet, PDF (1/20 Pages) Linear Technology – 10V, High Effi ciency, Buck-Boost Controller with Power Good

FEATURES
n _{Single Inductor Architecture Allows VIN Above,}
Below or Equal to V_OUT
n _{Power Good Output Indicator}
n _{2.7V to 10V Input and Output Range}
n _{Up to 96% Efficiency}
n _{Up to 10A of Output Current}
n _{All N-Channel MOSFETs, No RSENSE}^TM
n _{True Output Disconnect During Shutdown}
n _{Programmable Current Limit and Soft-Start}
n _{Optional Short-Circuit Shutdown Timer}
n _{Output Overvoltage and Undervoltage Protection}
n _{Programmable Frequency: 100kHz to 1MHz}
n _{Selectable Burst Mode}^® _Operation
n _{Available in 24-Lead (4mm × 4mm) Exposed Pad}
QFN Package
APPLICATIONS
n _{Palmtop Computers}
n _{Handheld Instruments}
n _{Wireless Modems}
n _{Cellular Telephones}
LTC3785-1
10V, High Efficiency,
Buck-Boost Controller
with Power Good
DESCRIPTION
The LTC^®3785-1 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 LTC3785-1 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 operation is user
controlled and can be enabled by driving the MODE pin
high. The LTC3785-1 includes a Power Good output that
indicates when the output voltage is within 7.5% of its
designed setpoint.
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.
TYPICAL APPLICATION
270pF
V_OUT
1.3k 215k
215k
127k
V_IN
V_SENSE
V_CC
I_SVIN
TG1
V_BST1
127k
1nF
FB
SW1
I_SSW1
12k
V_DRV
BG1
LTC3785-1
V_C
49.9k
RT
MODE
I_SVOUT
TG2
2.2nF
42.2k
PGOOD
V_BST2
RUN/SS
I_LSET
SW2
I_SSW2
CCM
BG2
GND
4.7μF
V_IN
2.7V
TO 10V
22μF
A
0.22μF
B
D
0.22μF
4.7μH
V_OUT
3.3V
5A
100μF
C
37851 TA01a
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)
37851 TA01b
37851f
1