LT3475 LINER [Linear Technology], LT3475 Datasheet - Page 5

• Manufacturer Part Number: LT3475
• Description: Dual Step-Down l 1.5A LED Driver
• Manufacturer: LINER [Linear Technology]

PI FU CTIO S
TYPICAL PERFOR A CE CHARACTERISTICS
OUT1, OUT2 (Pins 1, 10): The OUT pin is the input to the
current sense resistor. Connect this pin to the inductor
and the output capacitor.
LED1, LED2 (Pins 2, 9): The LED pin is the output of
the current sense resistor. Connect the anode of the LED
here.
V
circuitry and to the internal power switches and must be
locally bypassed.
SW1, SW2 (Pins 4, 7): The SW pin is the output of the
internal power switch. Connect this pin to the inductor,
switching diode and boost capacitor.
IN
1.28
1.27
1.24
1.22
1.26
1.25
1.23
U
35
30
20
15
10
25
(Pins 5, 6): The V
0
5
–50
0
Reference Voltage
Boost Pin Current
T
A
= 25°C
–25
U
0.5
SWITCH CURRENT (A)
0
TEMPERATURE (˚C)
25
1.0
U
IN
50
pins supply current to the internal
75
1.5
W
100
3475 G13
3475 G10
U
125
2.0
0
7
6
4
3
2
6
5
1
0
5
1
4
3
2
0
0
Quiescent Current
Minimum Input Voltage, Single
1.5A White LED
T
T
TO RUN
A
A
= 25°C
= 25°C
10
0.5
LED CURRENT (A)
TO START
V
IN
20
BOOST1, BOOST2 (Pins 3, 8): The BOOST pin is used to
provide a drive voltage, higher than the input voltage, to
the internal bipolar NPN power switch.
GND (Pins 15, Exposed Pad Pin 21): Ground. Tie the GND
pin and the exposed pad directly to the ground plane. The
exposed pad metal of the package provides both electrical
contact to ground and good thermal contact to the printed
circuit board. The exposed pad must be soldered to the
circuit board for proper operation. Use a large ground plane
and thermal vias to optimize thermal performance.
(V)
1
LED VOLTAGE
30
3475 G11
3475 G14
1.5
40
50
45
40
35
30
25
20
15
10
5
0
10
0
LT3475/LT3475-1
Open-Circuit Output Voltage and
Input Current
6
5
9
8
7
T
A
Minimum Input Voltage, Two Series
Connected 1.5A White LEDs
0
T
= 25°C
TO RUN
A
= 25°C
TO START
10
INPUT CURRENT
LT3475-1
0.5
LED CURRENT (A)
V
IN
20
OUTPUT VOLTAGE
(V)
LT3475
LT3475-1
LT3475
1
30
LED VOLTAGE
3475 G12
3475 G15
40
3475fb
5
14
12
10
8
6
4
2
0
1.5