SSL21081T_2T_3T_4T

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© NXP B.V. 2011. All rights reserved.

Preliminary data sheet

Rev. 2 — 6 December 2011

5 of 24

NXP Semiconductors

SSL21081T/2T/3T/4T

GreenChip drivers for LED lighting

7.2 Pin description

8.

Functional description

8.1 Converter operation

The converter in the SSL2108X is a Boundary Conduction Mode (BCM), peak current

controlled system. For the basic application diagram see Figure 4, for the waveforms see

Figure 5. This converter type operates at the boundary between continuous and

discontinuous mode. Energy is stored in inductor L each period that the switch is on. The

internal MOSFET switch is on. When the internal MOSFET switch is switched off, the

current continues to flow through the freewheel diode and the output capacitor. The

almost equal to half the peak switch current. A new cycle is started, as soon as the

Table 4.

Pin description

Symbol

Pin (SO8)

SSL2108X

Pin (SO12)

SSL2108X

Description

HV

1

1

high-voltage supply pin

SOURCE

2

3

low-side internal switch

VCC

3

4

supply voltage

NTC

4

5

LED temperature protection input

GND

6, 7

2,6,7,10,11

ground

DVDT

5

9

AC supply pin

TONMAX

-

8

brownout protection timer input

DRAIN

8

12

high-side internal switch

Fig 4.

Basic application diagram SSL2108X (SO8 variant)

001aan693

5

Rinrush

8

42

NTC

6, 7

GND

SOURCE

NTC

Rsense

L

DVDT

DRAIN

LEDs

1

3

HV

VCC

SSL2108X