ltc3490 Linear Technology Corporation, ltc3490 Datasheet - Page 4

• Manufacturer Part Number: ltc3490
• Description: Single Cell 350ma Led Driver
• Manufacturer: Linear Technology Corporation

PI FU CTIO S
LTC3490
CELLS (Pin 1): A logic input to set the low-battery and
undervoltage shutdown thresholds. A logic low (tied to
GND) will set the thresholds for 1 cell. A logic high (tied to
V
V
SW (Pin 3): Switch Input. Connect this pin to an external
inductor from V
GND (Pin 4): Circuit Ground.
LED (Pin 5): Output Drive Current to LED.
CAP (Pin 6): Filter Capacitor. A 4.7µF low ESR capacitor
should be tied to this pin.
LOBAT (Pin 7): Low active, open-drain logic output indi-
cating a low-battery condition.
TYPICAL PERFOR A CE CHARACTERISTICS
4
IN
IN
U
) will set the thresholds for 2 cells.
(Pin 2): Supply Voltage.
U
360
358
356
354
352
350
348
346
344
340
342
IN
2.8
.
I
V
LED
IN
U
= 2.4V
vs V
3
LED
3.2
W
V
LED
3.4
U
(V)
3.6
3.8
3490 G04
4
CTRL/SHDN (Pin 8): Analog Control Voltage and Shut-
down. When V
current varies according to the formula:
When V
at 350mA. When V
power shutdown.
Exposed Pad (Pin 9, DD Package): Ground. This pin must
be soldered to the PCB to provide both electrical contact
to ground and good thermal contact to the PCB.
I
LED
100
60
90
80
70
50
40
30
20
10
0
0
Efficiency vs I
=
CTRL
500
> V
100
•
IN
⎛
⎜
⎝
IN
• 0.2 < V
V
• 0.9, the LED drive current is clamped
CTRL
V
CTRL
V
V
I
LED
LED
IN
IN
IN
200
= 2.4V
= 1.2V
(mA)
< V
– .
CTRL
0 2
IN
300
⎞
⎟
⎠
• 0.2, then the part is in low
< V
mA
3490 G05
IN
400
• 0.9, the LED drive
3490fa