STMicroelectronics L6599ADTR

Overview

L6599ADTR from STMicroelectronics is an improved high-voltage resonant half-bridge controller IC designed for series-resonant LLC and LCC topologies. It delivers 50% complementary duty cycle with fixed 0.2–0.4 µs deadtime, supports up to 500 kHz variable-frequency operation, integrates 600 V-rail compatible high-side gate driver with synchronous bootstrap diode, and implements two-level overcurrent protection (frequency-shift + latched shutdown). It is used in high-efficiency AC-DC SMPS for LCD/PDP TVs and telecom power supplies.

For engineers reviewing the L6599ADTR datasheet, L6599ADTR pinout, L6599ADTR application, or L6599ADTR equivalent, key selection criteria include its resonant half-bridge control architecture, dual OCP thresholds (0.8 V and 1.5 V), programmable soft-start via Css/RFmin network, burst-mode threshold at STBY pin (1.24 V), and SO16N package compatibility with industrial thermal derating (R_thJA = 120 °C/W).

Technical Context

The L6599ADTR employs a relaxation oscillator with externally programmable frequency range (via RFmin and CF pins), where output voltage regulation is achieved by modulating switching frequency-not duty cycle-based on optocoupler feedback injected into RFmin. Its internal current mirroring ratio (1 A/A) enables precise scaling of sensed primary current into frequency shift.

It features dual independent protection paths: first-level OCP triggers non-linear soft-start discharge and frequency ramp-up when ISEN exceeds 0.8 V (50 mV hysteresis), while second-level latched shutdown activates at 1.5 V. The DIS pin provides hard latch-off for OTP/OVP, and PFC_STOP offers open-drain coordination with pre-regulators during fault or burst mode.

Key Specifications

Pinout & Package

Package: SO16N (Small Outline, 16-pin, narrow body, 1.27 mm pitch), RoHS-compliant, thermal resistance R_thJA = 120 °C/W at T_A = 50 °C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with FAN7688 and UCC256301, the L6599ADTR uniquely combines analog programmability, dual-threshold OCP, PFC coordination, and integrated synchronous bootstrap-making it optimal for cost-sensitive, high-volume resonant SMPS where reliability and design simplicity are prioritized over digital adaptability.

Availability

L6599ADTR is available at Aetrix Electronics and suitable for LCD/PDP TV power supplies, telecom SMPS, and industrial open-frame AC-DC converters requiring stable component supply, long-term lifecycle support, and SO16N package compatibility.

Supply support for L6599ADTR 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 L6599ADTR belongs to ST's high-voltage resonant controller product line, engineered specifically for efficient, reliable series-resonant half-bridge topologies in AC-DC power conversion systems demanding high power density and robust protection.

FAQ

What is the purpose of the N.C. pin (Pin 13) on the L6599ADTR?

Pin 13 is a no-connect spacer pin with no internal connection. Its sole function is to increase creepage distance between high-voltage pins (VBOOT, HVG, OUT) and adjacent signal pins-ensuring compliance with IEC/UL safety standards for reinforced insulation in AC-DC power supplies.

How does the L6599ADTR implement soft-start without output voltage overshoot?

The L6599ADTR uses a non-linear frequency-shift soft-start: the Css capacitor charges via an internal current generator, causing oscillator frequency to decay from a programmable maximum toward steady-state. This monotonic ramp prevents energy inrush and ensures controlled, overshoot-free output voltage rise-critical for electrolytic capacitor lifetime.

Can the L6599ADTR drive both MOSFETs directly without external gate drivers?

Yes. The L6599ADTR integrates matched ±0.3 A source / +0.8 A sink gate drivers on both high-side (HVG) and low-side (LVG) outputs, rated for 600 V floating operation. It drives standard 10–30 nC MOSFETs directly-no external drivers needed for typical 300–500 W resonant half-bridge designs.

What happens when the DELAY pin voltage reaches 3.5 V?

When DELAY pin voltage exceeds 3.5 V, the L6599ADTR enters latched shutdown: switching stops, soft-start capacitor discharges fully, and quiescent current drops to ≤400 µA. Recovery requires cycling Vcc below UVLO (≤7.45 V) to reset the latch-ensuring fail-safe protection during sustained overcurrent.