LT3498
PIN FUNCTIONS
V
OUT2
(Pin 7):
Drain of Output Disconnect PMOS.
Place a bypass capacitor from this pin to GND. See the
Applications Information section.
CAP2 (Pin 8):
Output of the OLED Driver. This pin is
connected to the cathode of the internal Schottky diode.
Place a bypass capacitor from this pin to GND.
SW2 (Pin 9):
Switch Pin. This is the collector of the in-
ternal NPN power switch. Minimize the metal trace area
connected to this pin to minimize EMI.
V
IN
(Pin 10):
Input Supply Pin. Must be locally by-
passed.
SW1 (Pin 11):
Switch Pin. Connect the inductor of the
white LED driver at this pin. Minimize metal trace area at
this pin to minimize EMI.
CAP1 (Pin 12):
Output of the White LED Driver. This pin is
connected to the cathode of the internal Schottky. Connect
the output capacitor to this pin and the sense resistor from
this pin to the LED1 pin.
Exposed Pad (Pin 13):
Ground. The Exposed Pad must
be soldered to the PCB.
BLOCK DIAGRAM
L2
10µF
C
IN
4.7µF
L1
15µF
9
CAP2
8
C2
0.47µF
SW2
10
V
IN
COMPARATOR
11
SW1
Q
S
DRIVER
Q1
OVERVOLTAGE
PROTECTION
CAP1
12
–
A2
R
START-UP
CONTROL
+
+
Σ
RAMP
GENERATOR
V
OUT2
7
C3
10µF
Q2
DISCONNECT
CONTROL
R
C
SHUNT
CONTROL
R
FB2
2.21MΩ
A5
C
C
DRIVER
SWITCH
CONTROL
2.3MHz
OSCILLATOR
A3
R
R
SENSE1
10Ω
C1
1µF
–
+
A1
–
+
+
A4
LED1
–
1
+
+
–
VREF
182kΩ
GND2
4
FB2
6
5
CTRL2
CTRL1 GND1
2
3
3498 BD
3498f
7
LINER [ LINEAR TECHNOLOGY ]
