LTC3530
5
3530fb
Load Transient Response in Fixed
Frequency Mode, No Load to 300mA
Load Transient Response in
Auto Burst Mode Operation,
No Load to 500mA
Typical Burst Mode Waveforms
Transition from Burst Mode
Operation to Fixed Frequency Mode Maximum Output Current vs V
IN
100μs/DIV
3530 G13
V
IN
= 3.6V
V
OUT
= 3.3V
C
OUT
= 22μF, X5R CERAMIC
LOAD
0.25A/DIV
V
OUT
100mV/DIV
100μs/DIV
3530 G14
V
IN
= 3.6V
V
OUT
= 3.3V
C
OUT
= 47μF, X5R CERAMIC + 100μF
LOW ESR TANTALUM
LOAD
0.25A/DIV
V
OUT
100mV/DIV
22μs/DIV
3530 G15
C
OUT
= 22μF, X5R CERAMIC
INDUCTOR
CURRENT
0.25A/DIV
V
OUT
50mV/DIV
200μs/DIV
3530 G16
C
OUT
= 22μF, X5R CERAMIC
INDUCTOR
CURRENT
0.5A/DIV
BURST
2V/DIV
V
OUT
200mV/DIV
T
A
= 25°C, unless otherwise specifi ed.
V
IN
(V)
I
OUT
1.5
200
CURRENT (mA)
400
800
1000
1200
3.5
5.5
2000
3530 G17
600
2.5 4.5
1400
1600
1800
250mA AT 1.8V
R
T
(Pin 1): Programs the Frequency of the Internal Oscil-
lator. Connect a resister from R
T
to ground.
f(kHz) = 33,170/R
T
(kΩ)
BURST (Pin 2): Used to Set the Automatic Burst Mode
Threshold. Connect 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
IN
to force fi xed frequency PWM 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 connnected from SW1 to
ground for a moderate effi ciency improvement. Minimize
trace length to keep EMI down.
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 the SW pin does not exhibit excessive voltage.
TYPICAL PERFORMANCE CHARACTERISTICS
PIN FUNCTIONS
