NXP Semiconductors SSL21084AT/1,118

Overview

SSL21084AT/1,118 from NXP Semiconductors is a high-voltage LED driver IC with integrated 600 V (DC) power switch, operating in boundary conduction mode (BCM) buck topology for mains-powered LED lamps. It delivers ±5 % LED current accuracy, supports direct PWM dimming, and features internal overtemperature, overcurrent, brownout, and output short protection. Designed for 230 V (AC) input LED lighting systems requiring compact, high-efficiency (up to 95 %) constant-current drive.

For engineers reviewing the SSL21084AT/1,118 datasheet, SSL21084AT/1,118 pinout, SSL21084AT/1,118 application, or SSL21084AT/1,118 equivalent, this page provides verified technical context, SO12 package mapping, valley-detection timing, R_DS(on) = 5 Ω (T_j = 25 °C), and confirmed brownout protection via TONMAX pin - all critical for LED driver design validation and BOM optimization.

Technical Context

The SSL21084AT/1,118 implements a peak-current-controlled BCM buck converter with zero-current switching (ZCS) turn-on and integrated valley detection on the DRAIN pin to minimize capacitive switching losses. Its internal 600 V MOSFET enables direct operation from rectified 230 V (AC) mains without external HV transistor.

Startup uses an internal HV current source from the HV pin, then transitions to dV/dt supply coupling from the DRAIN node; supply voltage is clamped at 14 V with 1.3 mA typical ICC consumption. Brownout protection is enabled via external capacitor on TONMAX pin, limiting maximum on-time to 15 µs (typical).

Key Specifications

Pinout & Package

SSL21084AT/1,118 is housed in a plastic SO12 package (SOT1196-1), featuring fused leads (pins 2, 6, 10, 11) for enhanced thermal transfer to PCB copper heat sink. Thermal resistance is 53 K/W (JEDEC 2s2p) and 121 K/W (free air, 2 cm × 3 cm, 2-layer board).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SSL21084T/1,118, the SSL21084AT/1,118 adds programmable brownout response via TONMAX, enabling stable dimming during line sags; versus SSL21083AT/1,118, it provides 600 V breakdown and SO12 thermal robustness essential for 230 V (AC) outdoor and retrofit applications.

Availability

SSL21084AT/1,118 is available at Aetrix Electronics and suitable for LED retrofit lamps, integrated downlight modules, dimmable wall-switch fixtures, and compact outdoor luminaires requiring stable component supply and long-term lifecycle support.

Supply support for SSL21084AT/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 markets.

The SSL2108 series belongs to NXP's GreenChip LED driver product line, engineered specifically for high-efficiency, low-BOM, single-stage AC-DC LED lighting drivers targeting mains-powered general illumination.

FAQ

What is the maximum input voltage the SSL21084AT/1,118 can handle?

The SSL21084AT/1,118 integrates a 600 V (DC) MOSFET, allowing direct connection to rectified 230 V (AC) mains (peak ~325 V). Its DRAIN pin withstands up to 600 V (DC), providing 85 V safety margin. The HV pin also supports up to 600 V (DC) with current limiting. This makes SSL21084AT/1,118 suitable for universal 230 V (AC) LED lighting applications without external HV components.

Does the SSL21084AT/1,118 support PWM dimming, and how is it implemented?

Yes, the SSL21084AT/1,118 supports direct PWM dimming via its NTC pin. Applying a digital low-voltage signal (e.g., 0–0.2 V) pulls the NTC pin below V_deact(tmr) (0.2 V typ), reducing LED current to zero. Raising the voltage above V_deact(tmr) restores output. No external transistor or level shifter is needed - the internal current source (−47 µA) and comparator thresholds enable seamless integration into microcontroller-driven dimming systems using SSL21084AT/1,118.

How does brownout protection work on the SSL21084AT/1,118?

Brownout protection on the SSL21084AT/1,118 limits maximum on-time (t_on(high) = 15 µs typ) when input voltage drops near LED string voltage. It uses the TONMAX pin: connecting an external capacitor allows adjustable timing - charging current I_TONMAX sets the threshold crossing time. If V_TONMAX reaches 4 V before t_on(high), the switch turns off early, reducing average LED current and preventing excessive input current. This function is exclusive to AT variants like SSL21084AT/1,118.

What thermal advantages does the SO12 package of the SSL21084AT/1,118 provide?

The SSL21084AT/1,118 uses the SO12 package (SOT1196-1) with four dedicated thermal leads (pins 2, 6, 10, 11) that connect die to PCB copper. On a JEDEC 2s2p test board, its R_th(j-a) is 53 K/W - 33 % lower than the SO8 variant (72 K/W). This enables higher continuous power (1 W vs. 0.6 W) and extends lifetime in thermally constrained LED lamps. The reduced thermal resistance directly improves reliability in enclosed fixtures where SSL21084AT/1,118 operates near ambient limits.

Can the SSL21084AT/1,118 be used without an auxiliary winding or external regulator?

Yes. The SSL21084AT/1,118 uses internal dV/dt supply coupling from the DRAIN pin - an integrated single-sided rectifier converts AC ripple into VCC supply current. During startup, an internal HV current source (350 µA typ at 100 V) powers the IC until dV/dt takes over. No auxiliary winding, transformer tap, or external linear regulator is required, simplifying layout and reducing cost - a core design advantage confirmed for SSL21084AT/1,118 in all official NXP application schematics.