SSL2109T

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© NXP B.V. 2012. All rights reserved.

Product data sheet

Rev. 2 — 26 April 2012

13 of 19

NXP Semiconductors

SSL2109T

GreenChip controller for LED lighting

12. Application information

A LED driver with the SSL2109T is a buck converter operating in BCM, see Figure 6.

Capacitor C3 buffers the IC supply voltage, which is powered via the HV pin at start-up

and via C5 during normal operation. Sense resistors R4 and R5 converts the current

through MOSFET Q1 into a voltage on pin Source. The value of these resistors defines

the maximum primary peak current on MOSFET Q1, and thus the LED current. Resistor

R6 reduces the reverse current into the DRIVER pin. The DRAIN pin is connected with the

drain of Q1 for valley detection.

In the example shown in Figure 6, the NTC pin is used for temperature protection. The

temperature level is set by Negative Temperature Coefficient (NTC) resistor R3 and

capacitor C4 reduces noise on the NTC pin. Further information can be found in the

SSL2109T application note.

Fig 6.

A typical SSL2109T application

SSL2109

HV

U1

DRAIN

VCC

GND

NTC

DVDT

SOURCE

R3

NTC

100 kΩ

C4

1 nF

C6

10 μF

160 V

D2

BYV25G-600

C3

1 μF

16 V

DRIVER

aaa-001746

1

2

3

4

6

5

8

7

C2

3.3 μF

400 V

C1

2.2 μF

385 V

L1

1 mH

500 mA SL

RV1

varistor 275 V

R1

fuse

L

J6-1

J6-2

L

N

1

1

10 Ω

R2

D1

DBLS105G

1

3

4

2

U

N

R6

C5

100 Ω,1206

120 pF

1 kV

L2

2.1 mH

1000 mA

R5

1.5, 1 %

R4

2.2, 1 %

Q1

MOSFET N

J5-1

LED+

LED-

LED+

LED-

J5-2

1

1