Overview
The L6699DTR, produced by STMicroelectronics, is a double-ended controller designed for series-resonant half bridge topology, supporting both LLC and LCC configurations. This controller provides a symmetrical complementary duty cycle, where the high-side and low-side switches are driven ON/OFF 180° out-of-phase for the same duration. Output voltage regulation is achieved by modulating the operating frequency. The L6699DTR features an adaptive deadtime adjustment to optimize the transition times of the half bridge midpoint. It also includes a high voltage floating structure capable of withstanding over 600 V, utilizing a synchronous-driven high voltage DMOS to replace the external fast-recovery bootstrap diode. The controller offers a high-accuracy externally programmable oscillator and a proprietary soft-start circuit to prevent hard-switching at startup.
Key Specifications
| Parameter | Min. | Typ. | Max. | Unit |
|---|---|---|---|---|
| VCC Operating Range | 8.85 | 16 | 16 | V |
| VCC Turn-on Threshold | 10 | 10.7 | 11.4 | V |
| VCC Turn-off Threshold | 7.45 | 8.15 | 8.85 | V |
| Boot Voltage (VBOOT) | -1 | - | 618 | V |
| Junction Temperature Range | -40 | - | 150 | °C |
| High-Side Gate Driver Current | -300 | - | 800 | mA |
| Low-Side Gate Driver Current | -300 | - | 800 | mA |
| Oscillation Frequency | 58.2 | 60 | 61.8 | kHz |
Key Features
- Symmetrical duty cycle, variable frequency control of resonant half bridge
- Self-adjusting adaptive deadtime
- High-accuracy oscillator
- 2-level Overcurrent Protection (OCP): frequency-shift and immediate shutdown
- Interface with PFC controller
- Anti-capacitive-mode protection
- Burst-mode operation at light load
- Input for brownout protection or power-on/off sequencing
- “Safe-start” procedure to prevent hard switching at startup
- 600 V rail compatible high-side gate driver with integrated bootstrap diode and high dv/dt immunity
Applications
- Switch Mode Power Supplies (SMPS) for LCD TVs, desktop and All-in-One (AIO) PCs, servers, and telecom power systems
- AC-DC adapters and open frame SMPS
Q & A
- What is the primary function of the L6699DTR controller?
The L6699DTR is a double-ended controller designed for series-resonant half bridge topology, supporting both LLC and LCC configurations, and provides symmetrical complementary duty cycle control.
- How does the L6699DTR regulate output voltage?
Output voltage regulation is achieved by modulating the operating frequency of the resonant half bridge.
- What is the role of the adaptive deadtime in the L6699DTR?
The adaptive deadtime is self-adjusted to best fit the transition times of the half bridge midpoint, optimizing the switching process.
- What protection features does the L6699DTR offer?
The L6699DTR includes 2-level OCP (frequency-shift and immediate shutdown), anti-capacitive-mode protection, and fast shutdown with automatic restart. It also has inputs for brownout protection and power-on/off sequencing.
- How does the L6699DTR handle startup to prevent hard-switching?
The controller features a proprietary soft-start circuit that prevents hard-switching at startup by controlling the half bridge to avoid unbalanced V·s applied to the transformer.
- What is the maximum voltage the high-side gate driver can withstand?
The high-side gate driver can withstand more than 600 V.
- What is the purpose of the burst-mode operation in the L6699DTR?
The burst-mode operation at light load keeps the converter input consumption as low as possible.
- How does the L6699DTR interface with a PFC controller?
The L6699DTR has an interface with the PFC controller that enables the switching-off of the pre-regulator during fault conditions or during burst-mode operation.
- What are the typical applications of the L6699DTR?
The L6699DTR is used in SMPS for LCD TVs, desktop and AIO PCs, servers, telecom power systems, and AC-DC adapters.
- What is the package type of the L6699DTR?
The L6699DTR is available in an SO16N package.
