SSL2129AT

All information provided in this document is subject to legal disclaimers.

© NXP B.V. 2012. All rights reserved.

Product data sheet

Rev. 2 — 23 October 2012

14 of 21

NXP Semiconductors

SSL2129AT

Dimmable LED controller IC

12. Application information

An LED driver with the SSL2129AT can be a buck, tapped buck or flyback converter

operating in BCM (see Figure 7). The tapped buck option offers the advantage of larger

duty factor and less peak current through the MOSFET switch, resulting in higher

efficiency and higher converter ratio. The recommended voltage swing on the DRAIN pin

is limited by the

V

overcome enabling lower output voltages.

It is recommended for 230 V applications that a TVS is placed after the rectifier bridge to

limit maximum voltage over the bus. In mains dimmable solutions, the bus voltage can

become substantially higher than the nominal mains voltage without clamping because of

line resonance and rectification. This can destroy the electrolytic capacitors, IC or

MOSFET. Open string protection can be added using the auxiliary winding voltage to

pull-down the NTC pin voltage. In addition, the TVS prevents voltage spikes due to for

example lighting surges.

Further information can be found in the SSL2129AT application note.

Fig 6.

A typical mains dimmable buck 120 V (AC) SSL2129AT application

BD1

MBS

BSP89

F1

SQQ 1

C1

0.22 μF

C2

0.22 μF

C4

1 μF

C3

470 μF

D1

ES1F

D3

IN4148W

L1

1 mH

L2

470 μH

SRR1210

R5

200 Ω

R4

84.5 kΩ

R3

Q3

1.5 MΩ

C7

15 nF

C5

220 pF

250 V

C6

82 pF

R6

9.1 Ω

Q2

Q1

FDD7N25

R1

0.43 Ω

U4

U7

U5

120 VAC

MOV1

V150LA1P

RGND

R10

220 kΩ

NTC

R7

D5

IN4148W

D2

ESF1

D4

1N4148W

D9

D6

2.4 V

2.2 kΩ

R8

226 kΩ

GND

40 V 427 mA

8

7

6

5

1

U1

IC

2

3

4

HV

VCC

NTC

SOURCE

DRAIN

GND

TONMOD

DRIVER

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