STMicroelectronics EVAL6520-1421

Overview

EVAL6520-1421 from STMicroelectronics is a demonstration board designed to drive T5 linear fluorescent lamps-specifically 14 W or 21 W high-efficiency (HE) variants-using the L6520 ballast controller and STT13005D bipolar transistors in a half-bridge topology. It operates from 198–264 V_rms AC mains, delivers preheating at 70 kHz, achieves ignition >46 kHz, and meets IEC61347-2-3, IEC61000-2-3, and EN55022 Class-C compliance.

For engineers reviewing the EVAL6520-1421 datasheet, EVAL6520-1421 pinout, EVAL6520-1421 application, or EVAL6520-1421 equivalent, this page provides verified board-level specifications, lamp interface behavior, EMI performance data, resonant network design parameters (C10 = 3.9 nF, L1 = 3 mH), and component-level implementation details for fluorescent lamp ballast validation.

Technical Context

The board implements a self-oscillating half-bridge ballast using two STT13005D NPN transistors driven by a 5.6:1 pulse transformer (T2), with resonant ignition and cathode preheating controlled by the L6520 IC. Lamp current regulation is achieved via resonant frequency tuning, while preheating voltage (>130 V_rms) and ignition voltage (<1000 V_pk) are enforced through precise R5 (2.94 kΩ) timing and C10/L1 network selection.

Power delivery uses a passive rectifier + bulk capacitor (C3 = 4.7 µF/400 V) without PFC, enabling <25 W input power and compatibility with European mains. The Vcc supply is derived from the resonant network (via D4/D5), introducing a 7.5 V offset compensated by Zener pair D6/D7 (6.8 V / 16 V) for symmetrical end-of-life detection.

Key Specifications

Availability

EVAL6520-1421 is available at Aetrix Electronics and suitable for fluorescent lighting system validation, ballast controller evaluation, lamp driver qualification, and EMI-compliant AC-powered lighting design requiring stable component supply and documented reference implementation.

Supply support for EVAL6520-1421 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 applications.

EVAL6520-1421 belongs to ST's lighting evaluation platform family, developed specifically to accelerate adoption of L6520-based electronic ballasts for energy-efficient T5 fluorescent systems in commercial and industrial lighting infrastructure.

FAQ

What lamp types does EVAL6520-1421 support?

EVAL6520-1421 supports only T5 linear fluorescent lamps rated at 14 W high-efficiency (T5-14W-HE) or 21 W high-efficiency (T5-21W-HE). It is not compatible with T8, T12, compact fluorescent, LED tubes, or non-HE variants. Lamp identification is based on physical dimensions (16 mm diameter), length (460 mm for 14 W, 610 mm for 21 W), and manufacturer-specified HE electrical characteristics.

Can EVAL6520-1421 operate from 115 VAC input?

No. EVAL6520-1421 is designed exclusively for 198–264 V_rms AC input per Table 1 in Doc ID 018537 Rev 2. Its bulk capacitor (C3 = 4.7 µF/400 V), resonant component values (C10 = 3.9 nF, L1 = 3 mH), and pulse transformer turns ratio (5.6:1) are optimized for European mains. Operation below 198 V_rms results in insufficient preheat voltage and failed ignition.

Is the EVAL6520-1421 RoHS compliant?

Yes. As confirmed in STMicroelectronics' official product change notices and material declarations for the EVAL6520-1421 board (Rev 2, November 2011), all components-including STT13005D transistors, L6520 IC, ITACOIL magnetics, and Panasonic ECQ capacitors-meet RoHS Directive 2011/65/EU requirements. Lead-free solder and halogen-free PCB substrate are used throughout.

Does EVAL6520-1421 include automatic re-lamp functionality?

Yes. Automatic re-lamp is implemented by routing the startup network (R2–R4) through the upper lamp cathode. When a lamp is removed or fails open-circuit, the absence of cathode conduction disables the L6520 startup sequence, preventing uncontrolled oscillation. This behavior is verified in Section 2 of Doc ID 018537 Rev 2 and confirmed in schematic Figure 4.