STMicroelectronics L6599N

Overview

L6599N 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 L6599N datasheet, L6599N pinout, L6599N application, or L6599N equivalent, key selection criteria include resonant topology compatibility, bootstrap-driven high-side drive capability, programmable soft-start timing, burst-mode light-load behavior, and dual-threshold OCP response under short-circuit conditions.

Technical Context

The L6599N implements a relaxation oscillator with externally programmable minimum frequency (via RFmin pin reference at 2.0 V ±4%) and timing capacitor (CF) to enable precise frequency modulation for output voltage regulation. Its control logic enforces fixed dead-time (0.2–0.4 µs) between high-side and low-side gate outputs to guarantee zero-voltage switching (ZVS) in resonant tanks.

It integrates two independent current-sense protection paths: first-level OCP triggers non-linear frequency shift via CSS discharge when ISEN exceeds 0.8 V (50 mV hysteresis), while second-level latching occurs at 1.5 V. The DIS pin provides hard latched shutdown (1.85 V threshold), and PFC_STOP offers open-drain coordination with upstream pre-regulators during fault or burst mode.

Key Specifications

Pinout & Package

DIP-16 package with creepage-enhanced layout: pin 13 is NC (high-voltage spacer), pins 14–16 form floating high-side domain (OUT/HVG/VBOOT), and GND (pin 10) serves as low-side return and bias reference.

Key Features

Applications

Equivalent & Alternatives

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

Compared with UCC256301, L6599N offers monolithic 600 V bootstrap and analog frequency modulation but lacks digital adaptability; versus IR21531, it adds full resonant control, dual OCP, and PFC coordination - making it uniquely suited for production-ready LLC SMPS.

Availability

L6599N is available at Aetrix Electronics and suitable for LCD/PDP TV power supplies, telecom SMPS, and open-frame AC-DC adapters requiring stable component supply, long-lifecycle support, and DIP-16 through-hole assembly compatibility.

Supply support for L6599N 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, power, microcontroller, and sensor solutions for industrial, automotive, and consumer markets.

The L6599N belongs to ST's high-voltage resonant controller product line, engineered specifically for LLC and series-resonant half-bridge converters in energy-efficient AC-DC and DC-DC power supplies.

FAQ

What is the purpose of the NC pin (pin 13) on the L6599N?

Pin 13 is a no-connect spacer placed between high-voltage pins (14–16) and low-voltage pins (1–12) to increase creepage distance on the PCB. It has no internal connection and is required to meet IEC 60950 and UL 60950 safety standards for reinforced insulation in AC-DC power supplies.

Can the L6599N drive GaN HEMTs directly?

Yes - its high-side driver supports −0.3 A source / +0.8 A sink peak current with <60 ns rise time and 600 V V_BOOT rating, matching common GaN e-HEMT gate requirements. However, external gate resistors and careful layout are needed to manage dV/dt-induced turn-on; the IC does not include active Miller clamp.

How does the L6599N implement burst-mode operation?

Burst-mode is triggered when the voltage on the STBY pin falls below 1.25 V, causing the IC to enter low-power idle state (quiescent current <400 µA). It exits burst-mode when STBY rises above 1.3 V, resuming switching without soft-start - enabling rapid load-response while maintaining sub-0.3 W no-load consumption.

Is the L6599N pin-compatible with the L6599D (SO-16N) version?

Yes - both share identical pin numbering, electrical characteristics, and functional behavior. The only differences are package (DIP-16 vs SO-16N), thermal resistance (80 vs 120 °C/W), and maximum power dissipation (1 W vs 0.83 W at rated ambient), requiring appropriate heatsinking for DIP-16 in high-power designs.