AN11136

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Application note

Rev. 1.2 — 1 September 2014

3 of 22

NXP Semiconductors

AN11136

SSL2109T/AT/SSL2129AT controller for SSL applications

1.

Introduction

This application note discusses the specific external MOSFET design considerations for

the SSL2109T/AT and the SSL2129AT.

The SSL2109T/AT and SSL2129AT platforms are specifically defined to address the

market of retrofit SSL applications. It provides a controller, with an external high-voltage

switch. The devices are optimized to make cost-effective, highly efficient buck converter

solutions for high-voltage LED strings or LED modules. The buck converter is one of the

most used Switch Mode Power Supply (SMPS) topologies.

The application note “Buck converter for SSL applications” (AN10876) provides general

information about buck converter applications. The application note

“SSL21081/SSL21083/SSL2109 non-dimmable buck converter in low ripple configuration”

(AN11041) describes a step-by-step design procedure for non-mains dimmable

applications.

Information and design tools for this IC can be found on the product page on the NXP web

site.

1.1 Functional description

The SSL2109A/AT and the SSL2129AT are Multi-Chip Module (MCM) SO8 packages.

They can handle up to 600 V (DC) at pins HV and DRAIN. The main features for all

variants are as follows (See Figure 1 and Figure 2):

Switch-mode buck controller with power-efficient boundary conduction mode of operation

with:

High Power Factor (> 0.9), depending on application

Fast transient response through cycle-by-cycle current control thus preventing:

Internal protections: