
LT3498
TYPICAL PERFORMANCE CHARACTERISTICS
T A = 25°C, unless otherwise speci?ed.
OLED Switching Waveforms
V SW
10V/DIV
V CAP1
50mV/DIV
LED Switching Waveforms
V CAP1
5V/DIV
V CTRL1
5V/DIV
LED Transient Response
V OUT2
10mV/DIV
AC COUPLED
SW2 VOLTAGE
10V/DIV
with No Load
I L
100mA/
DIV
500ns/DIV
V IN = 3.6V
FRONT PAGE APPLICATION
3498 G19
I L
200mA/
DIV
1ms/DIV
V IN = 3.6V
FRONT PAGE APPLICATION
3498 G20
INDUCTOR
CURRENT
50mA/DIV
V IN = 3.6V
V OUT2 = 16V
5μs/DIV
3498 G21
V OUT2
10mV/DIV
AC
COUPLED
SW2
VOLTAGE
10V/DIV
OLED Switching Waveforms
with 4mA Load
V OUT2
10mV/DIV
AC COUPLED
SW2
VOLTAGE
10V/DIV
OLED Switching Waveforms
with 35mA Load
CAP2
VOLTAGE
5V/DIV
V OUT2
VOLTAGE
5V/DIV
OLED Switching Waveforms
During Start-Up
INDUCTOR
CURRENT
200mA/DIV
V IN = 3.6V
V OUT2 = 16V
2μs/DIV
3498 G22
INDUCTOR
CURRENT
200mA/DIV
V IN = 3.6V
V OUT2 = 16V
500ns/DIV
3498 G23
INDUCTOR
CURRENT
100mA/DIV
V IN = 3.6V
V OUT2 = 16V
500μs/DIV
3498 G24
PIN FUNCTIONS
LED1 (Pin 1): Connection Point Between the Anode of the
Highest LED and the Sense Resistor. The LED current can
be programmed by:
CTRL2 (Pin 5): Dimming and Shutdown Pin. Connect
it below 75mV to disable the low noise boost converter.
As the pin voltage is ramped from 0V to 1.5V, the output
I LED 1 =
200mV
R SENSE 1
ramps up to the programmed output voltage.
FB2 (Pin 6): Feedback Pin. Reference voltage is 1.215V.
CTRL1 (Pin 2): Dimming and Shutdown Pin. Connect this
pin below 75mV to disable the white LED driver. As the
There is an internal 182k Ω resistor from FB2 to GND. To
achieve desired output voltage, choose R FB2 according to
the following formula:
pin voltage is ramped from 0V to 1.5V, the LED current
ramps from 0 to (I LED1 = 200mV / R SENSE1 ).
GND1, 2 (Pins 3, 4): Ground. Tie directly to local ground
R FB2 = 182 ?
V OUT2
1.215
1 k
plane. GND1 and GND2 are connected internally.
3498fa
6