NXP Semiconductors SSL21151T/1,118

Overview

SSL21151T/1,118 from NXP Semiconductors is a low-cost, non-dimmable LED driver IC with integrated 700 V high-voltage power switch, designed for isolated flyback or non-isolated buck-boost topologies. It delivers tightly regulated output current (±10 % accuracy), supports up to 5 W mains input power, and enables direct start-up from rectified AC mains without auxiliary supply at boot. It is used in compact retrofit LED lamps and down-light modules.

For engineers reviewing the SSL21151T/1,118 datasheet, SSL21151T/1,118 pinout, SSL21151T/1,118 application, or SSL21151T/1,118 equivalent, key selection criteria include primary-side sensing capability, R_DS(on) = 15.5 Ω (typ), 50.5 kHz switching frequency, ±3 % line/load regulation, and SO7 package compatibility for space-constrained lighting designs.

Technical Context

The SSL21151T/1,118 operates in Boundary Conduction Mode (BCM) with dV/dt-based demagnetization detection on the SENSE pin (threshold: 25–75 mV). Its cycle-by-cycle peak current control uses external RSOURCE resistor feedback and includes 325 ns leading-edge blanking to reject switching noise.

Internal JFET provides start-up current from DRAIN; operation begins when VCC exceeds 17 V (typ) and halts below 8.5 V (UVLO). Output short-circuit and open-circuit protections are latched, while OTP uses external thermistor biasing and trips at 150 °C (typ) with 50 K hysteresis.

Key Specifications

Pinout & Package

SSL21151T/1,118 is housed in an SO7 plastic small outline package (SOT1175-1), 7-pin, 3.9 mm body width, with exposed pad not connected internally. Thermal resistance R_th(j-a) = 136 K/W in free air on standard 2-layer PCB.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SSL21151T/1,118, the NCL30001DR2G offers higher current headroom but demands more external components for startup, while the ICE2QR0665Z delivers superior efficiency and EMI performance at the cost of increased design complexity and PCB area - making SSL21151T/1,118 optimal for cost- and size-sensitive ≤5 W retrofit lamps.

Availability

SSL21151T/1,118 is available at Aetrix Electronics and suitable for retrofit LED bulbs, down-light modules, and retail display lighting requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for SSL21151T/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 SSL2115X family belongs to NXP's GreenChip LED driver portfolio, engineered specifically for cost-sensitive, compact AC/DC LED lighting systems requiring high integration, primary-side regulation, and robust protection.

FAQ

What topology does the SSL21151T/1,118 support?

The SSL21151T/1,118 supports both isolated flyback and non-isolated buck-boost topologies. Its integrated 700 V MOSFET and primary-side sensing architecture eliminate the need for optocouplers or secondary-side feedback, enabling compact, low-BOM designs for ≤5 W applications. The device uses dV/dt detection on the SENSE pin to achieve zero-current switching in flyback mode.

Does the SSL21151T/1,118 require an external startup circuit?

No - the SSL21151T/1,118 integrates a high-voltage JFET connected to the DRAIN pin that supplies start-up current directly from rectified mains. Switching begins once VCC reaches 17 V (typ); after start-up, the auxiliary winding sustains VCC. This eliminates external startup resistors and capacitors, reducing component count and improving reliability in SSL21151T/1,118-based designs.

How does the SSL21151T/1,118 regulate LED current without an optocoupler?

The SSL21151T/1,118 uses primary-side sensing: it monitors reflected voltage on the SENSE pin to detect transformer demagnetization and calculates LED current indirectly via the SOURCE pin's external resistor (RSOURCE). This method achieves ±10 % current accuracy independent of mains voltage, LED forward voltage, and temperature - all without optocoupler or secondary feedback components in the SSL21151T/1,118 implementation.

What protection features are built into the SSL21151T/1,118?

The SSL21151T/1,118 includes OverTemperature Protection (OTP) with 150 °C trip threshold and 50 K hysteresis, LED short-circuit protection (latched shutdown), LED open-circuit protection (output voltage clamped to U_max/0.85), and UnderVoltage LockOut (UVLO) at 8.5 V. These protections ensure safe operation under fault conditions without external circuitry in SSL21151T/1,118-based lighting systems.

Is the SSL21151T/1,118 pin-compatible with other members of the SSL2115X family?

Yes - SSL21151T/1,118 shares identical SO7 (SOT1175-1) pinout and footprint with SSL21153T, differing only in internal R_DS(on) (15.5 Ω vs. 4.8 Ω) and peak drain current rating (±0.7 A vs. ±1.5 A). This allows scalable design reuse: the same PCB layout supports both 5 W (SSL21151T/1,118) and 10 W (SSL21153T) variants by adjusting transformer turns ratio and RSOURCE value.