STMicroelectronics L6585D

Overview

L6585D from STMicroelectronics is a high-voltage BCD-based combo IC integrating a transition-mode PFC controller and a half-bridge ballast controller with embedded gate drivers, programmable pre-heat/ignition timing, 3% oscillator precision, 1.2 µs dead time, and end-of-life lamp detection. It targets electronic fluorescent lamp (CFL and T5/T8) ballasts requiring stable ignition voltage control and compliance with lamp-to-ground or block-capacitor-to-ground configurations.

For engineers reviewing the L6585D datasheet, L6585D pinout, L6585D application, or L6585D equivalent, this device supports precise lamp aging detection via window comparator, auto-adjusting half-bridge over-current control during ignition/run modes, and PFC over-voltage protection with feedback disconnection - critical for Class D ballast design validation and EOL reliability certification.

Technical Context

The L6585D implements dual-control architecture: its PFC section uses current-mode transition-mode operation with a highly linear multiplier and THD optimizer, enabling wide-range mains operation (<±10% V_AC) and <5% THD across 20–100% load. The half-bridge controller features independent frequency programming per phase (pre-heat: 116.7 kHz typ., ignition: frequency-shifted, run: 60.2 kHz typ.) and synchronous bootstrap diode replacement.

Timing management relies on three dedicated pins: OSC sets base frequency via external capacitor; RF programs run/pre-heat frequencies via resistor dividers; TCH controls pre-heat duration via RC network with 4.63 V charge threshold and 1.50 V discharge threshold. End-of-life detection uses a programmable window comparator referenced to either fixed or CTR-tracked voltage, blanked during ignition.

Key Specifications

Pinout & Package

Package: SO-20 (Small Outline, 20-pin, 0.600" body width, 1.27 mm pitch). Pin mapping validated per STMicroelectronics datasheet Rev 5 (May 2007), Figure 3 (top view).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar electronic ballast controller applications.

Compared with L6585D, L6585DR offers identical electrical behavior with enhanced manufacturability and thermal robustness, while IRS2166D sacrifices lamp health monitoring for lower BOM cost - making L6585D the sole choice for safety-critical or maintenance-optimized fluorescent systems.

Availability

L6585D is available at Aetrix Electronics and suitable for compact fluorescent lamp (CFL) ballasts, T5/T8 linear fluorescent systems, lamp aging monitoring subsystems, and re-lamp-enabled emergency lighting requiring stable component supply and long-term production support.

Supply support for L6585D 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 L6585D belongs to ST's Lighting Control IC product line, engineered specifically for high-efficiency, digitally programmable electronic ballasts targeting energy-saving fluorescent lighting systems compliant with IEC 61000-3-2 and EN 61347-2-3.

FAQ

What is the purpose of the TCH pin and how is pre-heat time calculated?

The TCH pin controls pre-heat duration using an internal 30 µA current source charging an external capacitor CD through resistor RD. Pre-heat ends when TCH voltage drops from 4.63 V to 1.50 V; time is calculated as T_PRE = (4.63 × C_D/I_CH) + R_DC_D × ln(4.63/1.52). This ensures consistent filament heating before ignition, preventing premature lamp failure.

How does the L6585D implement end-of-life detection without external comparators?

L6585D integrates a programmable window comparator referenced to EOL-R. By connecting REOLP to ground, users set window amplitude (±220 mV or ±720 mV) and center voltage (fixed or tracking CTR). Asymmetric lamp voltage causes EOL-R to drift outside the window, triggering shutdown - eliminating need for discrete op-amps or voltage references.

Can the L6585D drive 600 V MOSFETs directly, and what gate drive strength is provided?

Yes - L6585D drives 600 V MOSFETs directly. Its PFG output delivers 300 mA source / 600 mA sink peak current; HSD/LSD outputs provide 290 mA source / 480 mA sink. All drivers include internal pull-down resistors (10 kΩ for PFG, 45 kΩ for LSD, 50 kΩ for HSD) and operate with V_BOOT up to 618 V, enabling robust gate control without external buffers.

What protection mechanisms prevent half-bridge shoot-through or MOSFET destruction?

L6585D prevents shoot-through via 1.2 µs programmable dead time between HSD and LSD outputs. It avoids MOSFET destruction using dual-threshold HBCS sensing: 0.91 V triggers frequency increase in run mode to limit current; 1.6 V triggers immediate latch in ignition or run mode. Combined with UVLO (10.3 V turn-off) and PFC OVP (3.4 V CTR threshold), it ensures fail-safe operation.