LTC3526-2_15 Datasheet, PDF (7/16 Pages) Linear Technology – 500mA 2MHz Synchronous Step-Up DC/DC Converters

LTC3526-2/LTC3526B-2
Block Diagram
V_IN
0.85V
TO 5V
C_IN
2.2µF
L1
2.2µH
V_OUT
3
V_IN
V_BEST
V_B
V_SEL
1
SW
4 ^SHDN
4M
ANTI-RING
SHUTDOWN SHUTDOWN
V_REF
UVLO
1.195V
START-UP
2MHz
CLK
OSC
GATE DRIVERS
AND
ANTI-CROSS
CONDUCTION
I_PK
COMP
I_PK
I_ZERO
LOGIC
MODE
CONTROL
THERMAL
TSD
SHUTDOWN
WAKE
EXPOSED
PAD
GND
7
2
WELL
SWITCH
V_{OUT 6}
–+
I_ZERO
COMP
SLOPE
COMP
FB
5
ERROR AMP
SLEEP COMP
V_REF
CLAMP
C_SS
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V_OUT
1.6V
TO 5.25V
R2
C_OUT
4.7µF
R1
Operation (Refer to Block Diagram)
The LTC3526-2/LTC3526B-2 are 2MHz synchronous boost
converters housed in a 6-lead 2mm × 2mm DFN package.
With the ability to start up and operate from inputs less
than 1V, these devices feature fixed frequency, current
mode PWM control for exceptional line and load regula-
tion. The current mode architecture with adaptive slope
compensation provides excellent transient load response,
requiring minimal output filtering. Internal soft-start and
internal loop compensation simplifies the design process
while minimizing the number of external components.
With its low R_DS(ON) and low gate charge internal N-chan-
nel MOSFET switch and P-channel MOSFET synchronous
rectifier, the LTC3526-2 achieves high efficiency over a wide
range of load currents. Automatic Burst Mode operation
maintains high efficiency at very light loads, reducing
the quiescent current to just 9µA. Operation can be best
understood by referring to the Block Diagram.
Low Voltage Start-Up
The LTC3526-2/LTC3526B-2 include an independent start-
up oscillator designed to start up at an input voltage of
0.85V (typical). Soft-start and inrush current limiting are
provided during start-up, as well as normal mode.
When either V_IN or V_OUT exceeds 1.4V typical, the IC
enters normal operating mode. When the output voltage
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