LTC3528_15 Datasheet, PDF (6/18 Pages) Linear Technology – 1A, 1MHz Synchronous Step-Up DC/DC Converters

LTC3528/LTC3528B
TYPICAL PERFORMANCE CHARACTERISTICS (T_A = 25°C unless otherwise noted)
Burst Mode Waveforms
V_OUT and I_IN During Soft-Start
Load Step Response (Fixed
Frequency, 3.6V to 5V)
V_OUT
20mV/DIV
INDUCTOR
CURRENT
100mA/DIV
V_IN = 3.6V
V_OUT = 5V
C_OUT = 22µF
C_FF = 33pF
I_LOAD = 30mA
5µs/DIV
V_OUT
1V/DIV
I_IN
200mA/DIV
SHDN PIN
3528 G20
V_IN = 1.2V
V_OUT = 3.3V
C_OUT = 10µF
L = 4.7µH
200µs/DIV
3528 G21
V_OUT
100mV/DIV
LOAD
CURRENT
200mA/DIV
V_IN = 3.6V
V_OUT = 5V
C_OUT = 10µF
L = 4.7µH
20µs/DIV
3528 G22
Load Step Response (Burst Mode
Operation, 3.6V to 5V, LTC3528)
Load Step Response (Fixed
Frequency, 1.2V to 3.3V)
Load Step Response (Burst Mode
Operation, 1.2V to 3.3V, LTC3528)
V_OUT
100mV/DIV
LOAD
CURRENT
200mA/DIV
V_IN = 3.6V
V_OUT = 5V
C_OUT = 10µF
L = 4.7µH
50µs/DIV
V_OUT
100mV/DIV
3528 G23
LOAD
CURRENT
100mA/DIV
V_IN = 1.2V
V_OUT = 3.3V
C_OUT = 10µF
L = 4.7µH
50µs/DIV
V_OUT
100mV/DIV
3528 G24
LOAD
CURRENT
100mA/DIV
V_IN = 1.2V
V_OUT = 3.3V
C_OUT = 10µF
L = 4.7µH
50µs/DIV
3528 G25
PIN FUNCTIONS
SHDN (Pin 1): Logic Controlled Shutdown Input. There is
an internal 4MΩ pull-down resistor on this pin.
• SHDN = High: Normal operation
• SHDN = Low: Shutdown, quiescent current < 1µA
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:
V_OUT
=
1.20V
•
₁₊
R2
R1
PGOOD (Pin 3): Power Good Comparator Output. This
open-drain output is low when V_FB < 10% from its regu-
lation voltage.
V_OUT (Pin 4): Output Voltage Sense and Drain Connection
of the Internal Synchronous Rectifier. PCB trace length
from V_OUT to the output filter capacitor (4.7µF minimum)
should be as short and wide as possible.
SW (Pin 5): Switch Pin. Connect inductor between SW
and V_IN. Keep PCB trace lengths as short and wide as
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_IN to minimize EMI.
PGND (Pin 6): Power Ground. Provide a short direct PCB
path between PGND and the (–) side of the input and
output capacitors.
3528fd
6