STMicroelectronics L6599DTR

Overview

L6599DTR from STMicroelectronics is a high-voltage resonant half-bridge controller IC designed for LLC and series-resonant DC-DC converters. It delivers 50 % complementary duty cycle, variable-frequency control up to 500 kHz, integrated 600 V-rail compatible high-side gate driver with synchronous bootstrap diode, dual-level overcurrent protection (frequency-shift + latched shutdown), and PFC interface - deployed in LCD/PDP TV power supplies and telecom SMPS.

For engineers reviewing the L6599DTR datasheet, L6599DTR pinout, L6599DTR application, or L6599DTR equivalent, key selection considerations include its fixed dead-time soft-switching architecture, non-linear soft-start for monotonic V_OUT rise, burst-mode operation at light load, and SO-16N package compatibility with industrial AC-DC adapter designs.

Technical Context

The L6599DTR implements a relaxation oscillator with externally programmable frequency range (via RFmin and CF pins), enabling output regulation through frequency modulation of the resonant tank. Its control logic enforces precise 180° phase shift between HVG and LVG outputs with 0.2–0.4 µs internally fixed dead-time to guarantee zero-voltage switching (ZVS) across load and line variations.

It integrates dual OCP stages: first-level frequency shift triggered at 0.8 V on ISEN (with 50 mV hysteresis) and second-level latched shutdown at 1.5 V, plus independent latched DIS input (1.85 V threshold) and line-sensing comparator (1.25 V trip with 15 µA hysteresis) for brownout protection - all coordinated via UVLO-controlled pull-downs on gate drivers during fault conditions.

Key Specifications

Pinout & Package

Package: SO-16N (16-pin small outline, narrow body, surface-mount). Pinout validated per STMicroelectronics datasheet Rev 3 (Feb 2009), Figure 2 and Table 2.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar resonant half-bridge controller applications.

Compared with UCC256301 and IR3584M, the L6599DTR offers analog simplicity, integrated bootstrap functionality, and hardware-based brownout/PFC coordination - making it optimal for cost-sensitive, high-volume resonant SMPS where firmware-free operation and safety-certified analog fault handling are prioritized.

Availability

L6599DTR is available at Aetrix Electronics and suitable for LCD/PDP TV power supplies, telecom SMPS, and desktop PC PSUs requiring stable component supply and long-term industrial availability.

Supply support for L6599DTR 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, delivering automotive, industrial, and power management solutions with emphasis on reliability and system-level integration.

The L6599 belongs to ST's high-voltage resonant controller product line, engineered specifically for LLC and series-resonant half-bridge topologies in energy-efficient AC-DC and DC-DC conversion - targeting applications demanding ZVS, low EMI, and robust analog fault protection.

FAQ

What is the purpose of the DELAY pin on the L6599DTR?

The DELAY pin implements a programmable OCP hold-off timer using an external RC network. When the ISEN pin exceeds 0.8 V, an internal 150 µA current charges the capacitor on this pin. At 2 V, the controller forces maximum frequency; at 3.5 V, it latches off. Discharge through the external resistor enables automatic restart once voltage falls below 0.3 V - providing controlled hiccup-mode protection during sustained overloads.

Can the L6599DTR drive GaN FETs directly?

No - the L6599DTR's gate drivers are optimized for silicon MOSFETs with typical Q_g ≤ 50 nC. Its 300 mA source/800 mA sink capability and 60 ns rise time are insufficient for fast GaN devices requiring sub-20 ns edges and >1 A peak drive. External gate driver boosters or dedicated GaN controllers (e.g., UCC27611) are required for GaN half-bridge implementations.

How does the PFC_STOP function interact with burst-mode operation?

During burst-mode (triggered when STBY pin voltage drops below 1.25 V), the PFC_STOP pin is actively pulled low to disable the upstream PFC controller - reducing no-load power consumption across the entire power train. This coordination is automatic and occurs without software intervention, ensuring synchronized shutdown of both pre-regulator and resonant stage during light-load intervals.

Is the L6599DTR recommended for new designs?

No - STMicroelectronics explicitly marks the L6599DTR as "Not for new design" in its official documentation (Rev 3, Feb 2009). While still in production and supported for legacy program continuity, new designs should evaluate ST's newer resonant controllers such as the L6599AD or digital alternatives like the STNRG388A to benefit from enhanced efficiency, integrated protections, and extended lifecycle assurance.