LTC3529 Linear Dimensions Semiconductor, LTC3529 Datasheet - Page 6

• Manufacturer Part Number: LTC3529
• Description: 1.5MHz Step-Up dc
• Manufacturer: Linear Dimensions Semiconductor

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BLOCK DIAGRAM
LTC3529
5.25V
OPERATION
The LTC3529 is a 1.5MHz synchronous boost converter in
an 8-lead 2mm × 3mm DFN package. The device operates
with an input voltage as low as 1.8V and features fi xed-
frequency current-mode PWM control for exceptional line
and load regulation. Internal MOSFET switches with low
R
high effi ciency over a wide range of load current.
PWM Operation
The LTC3529 operates in a fi xed-frequency PWM mode
using current-mode control at all load currents. At very
V
6
1.8V
IN
DS(ON)
TO
+
–
and low gate charge enable the device to maintain
C
3.3μF
IN
6
5
SNSGND
FAULT
OSCILLATOR
8
COMP
I
LIM
2A
V
IN
CLOCK
COMP
PWM
4.7μH
L1
PWM LOGIC
DRIVERS
+
AND
+
3
SHDN
ANTI-RING
light loads, the LTC3529 will exhibit pulse-skipping
operation.
Soft-Start
The LTC3529 provides soft-start by ramping the inductor
current limit from zero to its peak value in approximately
2ms. The internal soft-start capacitor is discharged in
the event of a fault, thermal shutdown or when the IC is
disabled via the SHDN pin.
SHUTDOWN
THERMAL
FAULT OR
FAULT TIMER
2
7
SW
22ms
V
RST
CURRENT
SENSE
IN
SD
R
SOFT-START
C
C
C
C2
BULK CONTROL
THERMAL SD
REFERENCE
4
SIGNALS
GM ERROR
AMPLIFIER
IZERO
COMP
PGND
–
+
9
1.25V
1.25V
GND (BP)
R1
1.875M
R2
625k
V
3529 BD
OUT
1
C
10μF
OUT
V
OUT
3529fa
, 5V