LT3498 データシートの表示（PDF） - Linear Technology

部品番号

コンポーネント説明

メーカー

LT3498

20mA LED Driver and OLED Driver with Integrated Schottky in 3mm x 2mm DFN

Linear Technology 

LT3498

APPLICATIONS INFORMATION— LED DRIVER

Table 2: Recommended Ceramic Capacitor Manufacturers

Taiyo Yuden

(800) 368-2496

www.t-yuden.com

AVX

(803) 448-9411

www.avxcorp.com

Murata

(714) 852-2001

www.murata.com

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, VCAP1 is clamped at 27V (typ). The LED

driver will then switch at a very low frequency to minimize

input current. The VCAP1 and input current during output

open-circuit are shown in the Typical Performance Char-

acteristics. Figure 3 shows the transient response when

the LEDs are disconnected.

Inrush Current

The LT3498 LED Driver has a built-in Schottky diode.

When supply voltage is applied to the VIN pin, an inrush

current flows 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 simplified as

follows:

= r

2•L

=

L

1

•C

–

r2

4 • L2

IPK

=

VIN

L

– 0.6

•

•

exp–





•

2





IL

200mA/DIV

VCAP1

10V/DIV

LEDs DISCONNECTED

AT THIS POINT

500μs/DIV

VIN = 3.6V

FRONT PAGE APPLICATION CIRCUIT

3498 F03

Figure 3. Transient Response with

LEDs Disconnected From Output

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

VIN (V)

4.2

4.2

4.2

4.2

r (Ω)

0.58

1.6

0.8

0.739

L (μH)

15

15

15

15

COUT (μF)

1

1

1

1

IP (A)

0.828

0.682

0.794

0.803

3498fa

10

Share Link: