LTC3528B Linear Technology Corporation, LTC3528B Datasheet - Page 6

• Manufacturer Part Number: LTC3528B
• Description: 1MHz Synchronous Step-Up DC/DC Converters
• Manufacturer: Linear Technology Corporation

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LTC3528/LTC3528B
TYPICAL PERFORMANCE CHARACTERISTICS
PIN FUNCTIONS
SHDN (Pin 1): Logic Controlled Shutdown Input. There is
an internal 4MΩ pull-down resistor on this pin.
FB (Pin 2): Feedback Input. Connect resistor divider tap
to this pin. The output voltage can be adjusted from 1.6V
to 5.25V by:
PGOOD (Pin 3): Power Good Comparator Output. This
open-drain output is low when V
lation voltage.
6
100mV/DIV
200mA/DIV
100mA/DIV
INDUCTOR
CURRENT
20mV/DIV
CURRENT
• SHDN = High: Normal operation
• SHDN = Low: Shutdown, quiescent current < 1μA
V
LOAD
V
OUT
V
OUT
OUT
Load Step Response (Burst Mode
Operation, 3.6V to 5V, LTC3528)
Burst Mode Waveforms
V
V
C
L = 4.7μH
V
V
C
C
I
= 1.20V • 1+
LOAD
IN
OUT
OUT
IN
OUT
OUT
FF
= 3.6V
= 3.6V
= 33pF
= 5V
= 22μF
= 5V
= 10μF
= 30mA
50μs/DIV
5μs/DIV
R2
R1
FB
3528 G20
3528 G23
< 10% from its regu-
200mA/DIV
100mA/DIV
100mV/DIV
SHDN PIN
CURRENT
1V/DIV
LOAD
V
V
OUT
OUT
I
IN
V
Load Step Response (Fixed
Frequency, 1.2V to 3.3V)
V
V
C
L = 4.7μH
V
V
C
L = 4.7μH
OUT
IN
OUT
OUT
IN
OUT
OUT
= 1.2V
= 1.2V
= 3.3V
= 10μF
= 3.3V
= 10μF
and I
IN
During Soft-Start
200μs/DIV
50μs/DIV
V
of the Internal Synchronous Rectifi er. PCB trace length
from V
should be as short and wide as possible.
SW (Pin 5): Switch Pin. Connect inductor between SW
and V
possible to reduce EMI. If the inductor current falls to
zero, or SHDN is low, an internal anti-ringing switch is
connected from SW to V
PGND (Pin 6): Power Ground. Provide a short direct PCB
path between PGND and the (–) side of the input and
output capacitors.
SGND (Pin 7): Signal Ground. Provide a short direct PCB
path between SGND and the (–) side of the input and
output capacitors.
OUT
(Pin 4): Output Voltage Sense and Drain Connection
IN
OUT
. Keep PCB trace lengths as short and wide as
to the output fi lter capacitor (4.7μF minimum)
(T
A
3528 G21
3528 G24
= 25°C unless otherwise noted)
100mV/DIV
200mA/DIV
100mV/DIV
100mA/DIV
CURRENT
CURRENT
LOAD
LOAD
V
V
OUT
OUT
IN
Load Step Response (Fixed
Frequency, 3.6V to 5V)
V
V
C
L = 4.7μH
Load Step Response (Burst Mode
Operation, 1.2V to 3.3V, LTC3528)
V
V
C
L = 4.7μH
to minimize EMI.
IN
OUT
OUT
IN
OUT
OUT
= 3.6V
= 1.2V
= 5V
= 10μF
= 3.3V
= 10μF
20μs/DIV
50μs/DIV
3528fa
3528 G22
3528 G25