LT3498
TYPICAL PERFORMANCE CHARACTERISTICS
LED Switching Waveforms
V
SW
10V/DIV
V
CAP1
5V/DIV
V
CTRL1
5V/DIV
T
A
= 25°C, unless otherwise specified.
OLED Switching Waveforms
with No Load
V
OUT2
10mV/DIV
AC COUPLED
LED Transient Response
V
CAP1
50mV/DIV
I
L
100mA/
DIV
V
IN
= 3.6V
FRONT PAGE APPLICATION
500ns/DIV
3498 G19
SW2
VOLTAGE
10V/DIV
I
L
200mA/
DIV
V
IN
= 3.6V
FRONT PAGE APPLICATION
1ms/DIV
3498 G20
INDUCTOR
CURRENT
50mA/DIV
V
IN
= 3.6V
V
OUT2
= 16V
5µs/DIV
3498 G21
OLED Switching Waveforms
with 4mA Load
V
OUT2
10mV/DIV
AC
COUPLED
SW2
VOLTAGE
10V/DIV
INDUCTOR
CURRENT
200mA/DIV
V
IN
= 3.6V
V
OUT2
= 16V
2µs/DIV
V
OUT2
10mV/DIV
AC COUPLED
SW2
VOLTAGE
10V/DIV
INDUCTOR
CURRENT
200mA/DIV
3498 G22
OLED Switching Waveforms
with 35mA Load
CAP2
VOLTAGE
5V/DIV
V
OUT2
VOLTAGE
5V/DIV
OLED Switching Waveforms
During Start-Up
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:
200mV
I
LED1
=
R
SENSE1
CTRL1 (Pin 2):
Dimming and Shutdown Pin. Connect this
pin below 75mV to disable the white LED driver. As the
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
plane. GND1 and GND2 are connected internally.
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
ramps up to the programmed output voltage.
FB2 (Pin 6):
Feedback Pin. Reference voltage is 1.215V.
There is an internal 182kΩ resistor from FB2 to GND. To
achieve desired output voltage, choose R
FB2
according to
the following formula:
⎛
V
⎞
R
FB2
=
182 •
⎜
OUT2
−
1
⎟
k
Ω
⎝
1.215
⎠
3498f
6
LINER [ LINEAR TECHNOLOGY ]
