LT3498EDDB#TRPBF Linear Technology, LT3498EDDB#TRPBF Datasheet - Page 10

• Manufacturer Part Number: LT3498EDDB#TRPBF
• Description: IC LED DRVR WT/OLED BCKLGT 12DFN
• Manufacturer: Linear Technology
• Type: Backlight, OLED, White LEDr

Specifications of LT3498EDDB#TRPBF

• Topology: PWM, Step-Up (Boost)
• Number Of Outputs: 1
• Internal Driver: Yes
• Type - Primary: Backlight
• Type - Secondary: OLED, White LED
• Frequency: 1.8MHz ~ 2.8MHz
• Voltage - Supply: 2.5 V ~ 12 V
• Voltage - Output: 32V
• Mounting Type: Surface Mount
• Package / Case: 12-DFN
• Operating Temperature: -40°C ~ 85°C
• Current - Output / Channel: 20mA
• Internal Switch(s): Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Efficiency: -

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AVX
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Overvoltage Protection
The LED driver of the LT3498 has an internal open-circuit
protection circuit. In the cases of output open circuit, when
the LEDs are disconnected from the circuit or the LEDs
fail open-circuit, V
driver will then switch at a very low frequency to minimize
input current. The V
open-circuit are shown in the Typical Performance Char-
acteristics. Figure 3 shows the transient response when
the LEDs are disconnected.
LT3498
APPLICATIONS INFORMATION—LED DRIVER
10
200mA/DIV
10V/DIV
V
CAP1
I
L
Figure 3. Transient Response with
LEDs Disconnected From Output
V
FRONT PAGE APPLICATION CIRCUIT
IN
CAP1
= 3.6V
CAP1
is clamped at 27V (typ). The LED
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and input current during output
500μs/DIV
LEDs DISCONNECTED
AT THIS POINT
3498 F03
Inrush Current
The LT3498 LED Driver has a built-in Schottky diode.
When supply voltage is applied to the V
current fl ows through the inductor and Schottky diode
and charges up the CAP1 voltage. The Schottky diode
for the LED Driver of the LT3498 can sustain a maximum
current of 1A.
For low DCR inductors, which are usually the case for this
application, the peak inrush current can be simplifi ed as
follows:
where L is the inductance, r is the DCR of the inductor
and C is the output capacitance.
Table 3 gives inrush peak currents for some component
selections.
Table 3: Inrush Peak Currents
I
V
PK
IN
4.2
4.2
4.2
4.2
=
=
(V)
=
2 • L
V
r
L • C
IN
L •
1
– 0.6
–
0.739
r (Ω)
0.58
1.6
0.8
4 • L
r
• exp –
2
2
L (μH)
15
15
15
15
•
2
C
OUT
1
1
1
1
IN
(μF)
pin, an inrush
0.828
0.682
0.794
0.803
I
P
(A)
3498fa