STMicroelectronics TN22-1500B-TR

Overview

TN22-1500B-TR from STMicroelectronics is a high-voltage silicon controlled rectifier (SCR) designed specifically as the main switching element in fluorescent tube electronic starter circuits. It features a clamping breakdown voltage of 1200–1500 V, low gate trigger current (<1.5 mA), and high holding current (>175 mA), enabling reliable lamp ignition with minimal external drive power in line-powered preheat-and-strike topologies.

For engineers reviewing the TN22-1500B-TR datasheet, TN22-1500B-TR pinout, TN22-1500B-TR application, or TN22-1500B-TR equivalent, key selection criteria include repetitive off-state voltage rating (400 V), surge current capability (22 A @ 8.3 ms), thermal resistance (3 °C/W junction-to-case), gate trigger voltage (≤3 V), and compatibility with IPAK/TO-220AB mounting for convection-cooled ballast assemblies.

Technical Context

The TN22-1500B-TR operates as a latching thyristor switch triggered by gate current from an auxiliary SCR-controlled RC network. Its high dV/dt immunity (≥500 V/µs at Tj = 110 °C) prevents false turn-on during mains transients, while its 1200–1500 V breakdown voltage ensures sufficient overvoltage clamping to reliably ignite cold fluorescent tubes.

It functions in a three-phase starter sequence: filament preheating (sustained conduction via C1 hold charge), controlled turn-off (gate shorted by fired SCR), and high-energy ignition pulse generation (inductor flyback clamped at VBR). The device remains latched until current falls below 175 mA, ensuring full half-cycle energy delivery per strike attempt.

Key Specifications

Pinout & Package

The TN22-1500B-TR is supplied in the IPAK (TO-251AA) package - a surface-mount variant of TO-220 with isolated tab and gull-wing leads - optimized for automated assembly and thermal transfer to PCB copper planes.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fluorescent starter SCR applications.

Compared with TN22-1500B-TR, the TN22-1200H reduces ignition margin but simplifies compliance testing, while the S4006L trades gate sensitivity for thermal headroom-neither offers the same combination of low-trigger, high-clamp, and high-hold performance in compact IPAK form.

Availability

TN22-1500B-TR is available at Aetrix Electronics and suitable for fluorescent lamp starters, electronic ballast preheat modules, and compact CFL ignition circuits requiring stable component supply, long-life reliability, and consistent high-voltage clamping behavior.

Supply support for TN22-1500B-TR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The TN22 belongs to ST's legacy power thyristor product line, engineered specifically for electromagnetic compatibility and long-term reliability in mains-connected lighting control applications where robustness outweighs digital programmability.

FAQ

What is the function of the TN22-1500B-TR in a fluorescent starter circuit?

The TN22-1500B-TR acts as the main high-energy switching thyristor: it latches on during filament preheating using gate current from an auxiliary SCR, then turns off when the SCR shorts its gate, allowing the ballast inductor to generate a clamped high-voltage ignition pulse (1200–1500 V) across the tube electrodes.

Can TN22-1500B-TR be used with 115 VAC mains systems?

Yes, but with design adaptation: its 400 V V_DRM provides adequate margin for 115 VAC (peak ~162 V), though the 1200–1500 V V_BR may exceed ignition needs for shorter tubes. Preheat timing and gate RC values must be re-optimized to maintain 2–3 s warm-up at lower peak voltages.

Is heatsinking required for TN22-1500B-TR in typical starter applications?

Heatsinking is not required for standard 2 A RMS operation at ≤95 °C case temperature due to its 3 °C/W R_th(j-c); however, PCB copper pour ≥250 mm² under the tab is recommended for thermal stability in sealed enclosures or high-ambient environments (>60 °C).

How does TN22-1500B-TR differ from standard triacs used in dimmers?

Unlike bidirectional triacs, the TN22-1500B-TR is unidirectional and optimized for single-quadrant switching in rectified DC-like starter waveforms. It prioritizes high dV/dt immunity and precise V_BR clamping over phase-angle control, making it unsuitable for AC dimming but ideal for repeatable, high-energy ignition pulses.