LTC3532
5
3532fc
SW2
5V/DIV
SW1
5V/DIV
INDUCTOR
CURRENT
500mA/DIV
V
OUT
100mV/DIV
4μs/DIV
V
IN
= 4.2V
V
OUT
= 3.3V
I
LOAD
= 20mA
C
OUT
= 22μF
3535 G17
SW2
5V/DIV
SW1
5V/DIV
INDUCTOR
CURRENT
500mA/DIV
V
OUT
100mV/DIV
4μs/DIV
V
IN
= 3.75V
V
OUT
= 3.3V
I
LOAD
= 20mA
C
OUT
= 22μF
340612 G16
PI FU CTIO S
UUU
RT (Pin 1): Timing Resistor to Program the Oscillator
Frequency. The programming range is 300kHz to 2MHz.
f(kHz) =
48,000
R
T
(kΩ)
BURST (Pin 2): Used to Set the Automatic Burst Mode Op-
eration Threshold. Place a resistor and capacitor in parallel
from this pin to ground. See the Applications Information
section for component value selection. For manual control,
ground the pin to force Burst Mode operation, connect to
V
OUT
to force fi xed frequency mode.
SW1 (Pin 3): Switch Pin Where the Internal Switches A
and B are Connected. Connect inductor from SW1 to SW2.
An optional Schottky diode can be connected from SW1
to ground. Minimize trace length to minimize EMI.
SW2 (Pin 4): Switch Pin Where the Internal Switches C
and D are Connected. For applications with output voltages
over 4.3V, a Schottky diode is required from SW2 to V
OUT
to ensure SW2 does not exhibit excess voltage.
GND (Pin 5): Signal and Power Ground for the IC.
V
OUT
(Pin 6): Output of the Synchronous Rectifi er. A fi lter
capacitor is placed from V
OUT
to GND.
V
IN
(Pin 7): Input Supply Pin. Supplies current to the
inductor through SW1 and supplies internal V
CC
for the
IC. A ceramic bypass capacitor as close to the V
IN
pin and
GND (Pin 5) is required.
Switch Pins Before Entering
Buck Mode Output Ripple at 100mA Load Burst Mode, Boost
TYPICAL PERFOR A CE CHARACTERISTICS
UW
T
A
= 25°C, unless otherwise specifi ed.
Burst Mode, Buck-Boost Burst Mode, Buck
SW1
2VDIV
SW2
2VDIV
40ns/DIV
V
IN
= 4V
VOUT = 3.3V
I
LOAD
= 100mA
3535 G13
V
OUT
50mV/DIV
V
OUT
50mV/DIV
V
OUT
50mV/DIV
400ns/DIV
V
OUT
= 3.6V
I
OUT
= 100mA
C
OUT
= 10μF
3535 G14
V
IN
= 2.4V
V
IN
= 3.6V
V
IN
= 4.5V
SW1
5V/DIV
SW2
5V/DIV
INDUCTOR
CURRENT
500mA/DIV
V
OUT
100mV/DIV
4μs/DIV
V
IN
= 2.4V
V
OUT
= 3.3V
I
LOAD
= 20mA
C
OUT
= 22μF
3535 G15
