SW

IN

1

L

LED

LED

IN

1

f

V

I

2

V

V

V

L

'



SW

on

IN

LED

f

t

V

V







1

LED

IN

on

1

L

L

V

V

t

I

2



'

SW

IN

LED

f

ns

400

V

V

K

J

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

3

4

5

6

7

8

9

10

R

C007

TPS92511

www.ti.com

SNVS901A – MARCH 2014 – REVISED MAY 2014

150

10

350

4.32

500

3.01

7.3.7 Integrated MOSFET

The TPS92511 integrates a N-channel power MOSFET, the drain of which is connected to the LX pin. When the

integrated MOSFET is turned on, the resistance across the LX and GND pins is typically 1.4

Ω. The integrated

MOSFET has a fixed current limit of 1.2A to protect the application circuit during critical operation conditions like

short circuit of the LED string. Once the limit is hit, the integrated MOSFET turns off immediately for 34 µs to let

the inductor discharge.

The minimum on-time of the integrated MOSFET is 400 ns. It may be hit at a high switching frequency and a

level higher than the programmed value, and the LED string and/or the inductor may be damaged as a result.

(3)

7.3.8 Inductor Selection

Operating in the continuous conduction mode (CCM) is required in the TPS92511 application circuit. In the CCM,

considering the on-period, the peak-to-peak inductor current ripple (2

(4)

Because

(5)

(6)

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