Overview
The L6699D, produced by STMicroelectronics, is an enhanced high-voltage resonant controller designed for series-resonant half bridge topology, supporting both LLC and LCC configurations. It features 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 IC includes a high-accuracy externally programmable oscillator and a proprietary circuit to prevent hard-switching at startup. It also supports burst-mode operation at light loads to minimize input consumption.
The L6699D incorporates a high voltage floating structure capable of withstanding over 600 V, using a synchronous-driven high voltage DMOS to replace the external fast-recovery bootstrap diode. The IC includes multiple protection features such as current sense input for overcurrent protection (OCP), delayed shutdown with automatic restart, and prevention of capacitive mode operation to ensure soft-switching.
Key Specifications
| Parameter | Min. | Typ. | Max. | Unit |
|---|---|---|---|---|
| VCC (IC supply voltage) | 8.85 | 16 | 16 | V |
| VBOOT (Floating supply voltage) | -1 | - | 618 | V |
| Tj (Junction temperature operating range) | -40 | - | 150 | °C |
| fosc (Oscillation frequency) | 58.2 | 60 | 61.8 | kHz |
| Deadtime self-adjustment range | 0.23 µs | - | 0.7 µs | - |
| High-side gate driver current | -300 mA | - | 800 mA | - |
| Low-side gate driver current | -300 mA | - | 800 mA | - |
| Ptot (Power dissipation at tamb = 50 °C) | - | - | 0.83 W | - |
Key Features
- Symmetrical duty cycle, variable frequency control of resonant half bridge
- Self-adjusting adaptive deadtime
- High-accuracy oscillator
- 2-level 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 prevents hard switching at startup
- 600 V rail compatible high-side gate driver with integrated bootstrap diode and high dv/dt immunity
- -300/800 mA high-side and low-side gate drivers with UVLO pull-down
Applications
- Switch-Mode Power Supplies (SMPS) for LCD TVs, desktop and All-In-One (AIO) PCs, servers, and telecom power systems
- AC-DC adapters
- Open frame SMPS
Q & A
- What is the primary function of the L6699D?
The L6699D is a double-ended controller for series-resonant half bridge topology, supporting both LLC and LCC configurations.
- How does the L6699D regulate output voltage?
Output voltage regulation is achieved by modulating the operating frequency.
- What protection features does the L6699D include?
The IC includes current sense input for OCP, delayed shutdown with automatic restart, and prevention of capacitive mode operation.
- What is the purpose of the high voltage floating structure in the L6699D?
The high voltage floating structure is capable of withstanding over 600 V and uses a synchronous-driven high voltage DMOS to replace the external fast-recovery bootstrap diode.
- How does the L6699D handle startup to prevent hard-switching?
The IC includes a proprietary circuit to prevent hard-switching at startup by controlling the half bridge to avoid unbalanced V·s applied to the transformer.
- What is the burst-mode operation in the L6699D?
The IC can enter a controlled burst-mode operation at light loads to minimize input consumption.
- What are the typical applications of the L6699D?
Typical applications include SMPS for LCD TVs, desktop and AIO PCs, servers, telecom power systems, AC-DC adapters, and open frame SMPS.
- What is the operating temperature range of the L6699D?
The junction temperature operating range is from -40°C to 150°C.
- How is the oscillator frequency set in the L6699D?
The oscillator frequency is set by an externally programmable oscillator using a high-accuracy timing capacitor and resistor network.
- What is the maximum power dissipation of the L6699D at 50°C ambient temperature?
The maximum power dissipation is 0.83 W.
