Overview
The UCC256304, produced by Texas Instruments, is an ultra-wide VIN LLC (LLC - Line Load Control) resonant controller designed to enable low standby power consumption. This controller is part of a comprehensive power system that integrates with a PFC (Power Factor Correction) stage, minimizing the need for external components. It features a hybrid hysteretic control (HHC) algorithm, which provides best-in-class transient response and simplifies compensation design. The UCC256304 is optimized for low power operation, achieving a standby power of 75 mW with PFC enabled, and it supports compliance with the CoC Tier II standard. The device includes advanced burst mode operation, adaptive dead-time, and internal high-side gate drivers, making it suitable for a variety of high-power applications.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Supply Voltage (VCC) | 0.5 | 0.6 | 0.7 | V |
| Bulk Voltage Sense Start (VBLKStart) | 1.01 | 1.04 | 1.08 | V |
| Bulk Voltage Sense Stop (VBLKStop) | 0.83 | 0.87 | 0.93 | V |
| Thermal Shutdown Temperature (TJ_r) | 125 | 145 | °C | |
| Operating Frequency Range | 35 kHz | 1 MHz | ||
| Gate Drive Output Rise Time (tr(LO)) | 18 ns | 35 ns | 50 ns | |
| Gate Drive Output Fall Time (tf(LO)) | 15 ns | 25 ns | 50 ns | |
| Minimum Dead Time (tDT(min)) | 100 ns | |||
| Maximum Dead Time (tDT(max)) | 150 µs |
Key Features
- Hybrid Hysteretic Control (HHC): Provides best-in-class transient response and simplifies compensation design.
- Optimized Low Power Features: Enables 75 mW standby power design with PFC on and supports compliance with CoC Tier II standard.
- Advanced Burst Mode: Programmable burst power level that adaptively changes with input voltage, ensuring high light-load efficiency and reduced no-load power.
- Fast Exit from Burst Mode: Quickly transitions out of burst mode to maintain efficiency.
- Improved Capacitive Region Avoidance Scheme: Prevents operation in the capacitive region, enhancing overall efficiency.
- Adaptive Dead-Time: Automatically adjusts dead-time to provide optimum efficiency and security of operation.
- Internal High-Side Gate Drivers: Capable of driving up to 1-kW peak/500-W continuous power.
- Robust Soft Start: No hard switching, ensuring smooth startup.
- Comprehensive Protection Features: Includes over temperature, output over voltage, input over and under voltage protection, and three levels of over current protection.
Applications
- Digital TV SMPS
- AC-DC Adapters
- Multi-Functional Printers
- Projectors
- Merchant DC-to-DC
- High Power Battery Charging
- DIN Rail Power Supply
- Multi-Axis Servo
- ATX Power Supply
- Appliances
- LED Lighting Applications
Q & A
- What is the primary function of the UCC256304?
The UCC256304 is an ultra-wide VIN LLC resonant controller designed to enable low standby power consumption in power systems, particularly when integrated with a PFC stage.
- What is Hybrid Hysteretic Control (HHC) in the UCC256304?
HHC is a control algorithm that provides best-in-class transient response and simplifies compensation design by making the system a first-order system.
- How does the UCC256304 achieve low standby power?
The UCC256304 achieves low standby power through optimized low power features, advanced burst mode operation, and adaptive dead-time, enabling a standby power design of 75 mW with PFC on.
- What are the key protection features of the UCC256304?
The UCC256304 includes over temperature, output over voltage, input over and under voltage protection, and three levels of over current protection.
- What is the operating frequency range of the UCC256304?
The operating frequency range of the UCC256304 is from 35 kHz to 1 MHz.
- How does the adaptive dead-time feature work in the UCC256304?
The adaptive dead-time feature automatically adjusts the dead-time to provide optimum efficiency and security of operation by monitoring the half-bridge switched node.
- What are the typical applications of the UCC256304?
The UCC256304 is used in various applications including digital TV SMPS, AC-DC adapters, multi-functional printers, projectors, and LED lighting applications.
- How does the UCC256304 handle capacitive region avoidance?
The UCC256304 includes an improved capacitive region avoidance scheme that prevents operation in the capacitive region, enhancing overall efficiency.
- What is the role of the high-voltage startup JFET in the UCC256304?
The high-voltage startup JFET provides the initial power to start the PFC and LLC stages and monitors the AC line voltage for x-capacitor discharge function.
- How does the UCC256304 support fast exit from burst mode?
The UCC256304 quickly transitions out of burst mode to maintain efficiency, ensuring fast exit from burst mode.
