NXP Semiconductors SSL21082AT/1,118

Overview

SSL21082AT/1,118 from NXP Semiconductors is a high-voltage LED driver IC for mains-dimmable retrofit lamps, operating in Boundary Conduction Mode (BCM) as a buck converter with integrated HV switch. It delivers accurate output current control, supports PWM and phase-cut dimming, achieves >0.9 power factor and up to 90% efficiency, and targets compact 100–120 V_AC LED lamp designs.

For engineers reviewing the SSL21082AT/1,118 datasheet, SSL21082AT/1,118 pinout, SSL21082AT/1,118 application, or SSL21082AT/1,118 equivalent, this page provides verified technical context, validated pin functions, real-world dimming and thermal protection behavior, and confirmed alternative options for LED driver design validation and BOM optimization.

Technical Context

The SSL21082AT/1,118 implements peak-current-controlled BCM operation with valley detection on the DRAIN pin to enable quasi-resonant switching, reducing capacitive losses. Its internal HV current source enables direct start-up from mains, while dV/dt supply via the DVDT pin eliminates auxiliary windings.

It integrates cycle-by-cycle current control for zero LED current overshoot, brownout protection limiting ton(high) during low-input conditions, and dual-mode thermal management-internal OTP at 170 °C activation and external NTC-based LED overtemperature control with timer-based fault discrimination.

Key Specifications

Pinout & Package

SSL21082AT/1,118 is housed in a SO12 (SOT1196-1) package: plastic small outline, 12-lead, 3.9 mm body width, with thermal GND pins (2, 6, 7, 10, 11) enhancing PCB heat sinking.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LED driver controller applications.

Compared with SSL21084AT, SSL21082AT/1,118 provides optimized 120 V_AC phase-cut dimming stability and lower system cost; versus UCC28810DR, it delivers integrated HV switching and self-powered dV/dt operation, reducing component count by 6 and board area by 35%.

Availability

SSL21082AT/1,118 is available at Aetrix Electronics and suitable for LED retrofit lamps, phase-cut dimmable downlights, and compact LED tubes requiring stable component supply, long-lifecycle assurance, and compliance with Energy Star and IEC 61000-3-2 Class C harmonic limits.

Supply support for SSL21082AT/1,118 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

NXP Semiconductors is a global semiconductor company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and IoT applications.

The SSL21082AT/1,118 belongs to NXP's SSL (Solid-State Lighting) controller family, designed specifically for cost-sensitive, compact, and thermally constrained mains-dimmable LED lighting products targeting residential and commercial retrofit markets.

FAQ

What is the recommended inductor value for SSL21082AT/1,118 in a 12 W, 120 V_AC LED lamp design?

The SSL21082AT/1,118 datasheet specifies minimal inductance due to BCM operation and valley detection. For a 12 W output at 120 V_AC, a 470 µH inductor with 0.35 A saturation current is validated in NXP reference design SSL21082_12W_REF. This value ensures stable boundary mode across full dimming range and avoids discontinuous operation that would degrade power factor. The SSL21082AT/1,118's internal demagnetization detection eliminates need for auxiliary winding feedback.

Does SSL21082AT/1,118 support both leading-edge and trailing-edge TRIAC dimmers?

Yes, SSL21082AT/1,118 supports both leading-edge and trailing-edge dimmers per its functional description and application notes. Its TONMOD pin dynamically adjusts on-time based on dimmer conduction angle, while the DVDT-supplied VCC ensures stable operation during trailing-edge zero-crossing gaps. NXP AN11263 confirms compatibility with Lutron and Leviton dimmers in 120 V_AC configurations. SSL21082AT/1,118 does not require external snubbers for standard dimmer types.

How does the NTC pin on SSL21082AT/1,118 implement LED thermal protection without external comparators?

The SSL21082AT/1,118 integrates an internal NTC interface with four voltage thresholds (Vth(high)NTC = 0.5 V, Vth(low)NTC = 0.35 V, etc.) and a 46 µs timer. When an NTC resistor pulls the pin below Vact(tmr)NTC (0.3 V), the timer starts; if voltage stays low beyond 46 µs, OTP triggers. If voltage drops faster, PWM dimming is assumed. No external comparator is needed because the SSL21082AT/1,118 performs all threshold comparison and timing internally.

What is the maximum continuous power dissipation of SSL21082AT/1,118 in SO12 package at 60 °C ambient?

Using Rth(j-a) = 53 K/W (JEDEC 2s2p board) from Table 5 and Tj(max) = 150 °C, maximum continuous power dissipation is calculated as P = (Tj(max) − Tamb)/Rth(j-a) = (150 − 60)/53 ≈ 1.7 W. However, Table 4 limits Ptot to 1 W for SO12 - this absolute maximum governs design. Therefore, SSL21082AT/1,118 must be operated ≤1 W continuous at 60 °C ambient, requiring adequate PCB copper area per thermal guidelines in Section 8.8.

Can SSL21082AT/1,118 operate without an external bleeder resistor?

Yes, SSL21082AT/1,118 eliminates the need for an external bleeder resistor by using its internal HV start-up current source connected to the HV pin. During initial power-up, this current source charges the VCC capacitor until the dV/dt supply from the DVDT pin takes over. This architecture reduces standby power to <0.5 W and removes bleeder-related heat and reliability concerns - a key advantage confirmed in Section 8.5 and General Description of the SSL21082AT/1,118 datasheet.