Overview
The UCC28740DR from Texas Instruments is a Constant-Voltage, Constant-Current (CVCC) Flyback controller designed for high-performance power supply applications. It utilizes optocoupled feedback for constant-voltage regulation and primary-side regulation (PSR) for constant-current regulation. This controller is optimized for ultra-low standby power consumption without compromising startup time or output transient response. It features an internal 700-V startup switch, resonant-ring valley-switching operation, and frequency dithering to ease EMI compliance. The device is packaged in a SOIC-7 package and supports design customization using the WEBENCH® Power Designer tool.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| No-Load Power Capability | < 10 | mW |
| Startup Switch Voltage | 700 | V |
| Maximum Switching Frequency | 100 | kHz |
| Voltage Regulation Accuracy | ±1% | |
| Current Regulation Accuracy | ±5% | |
| Package Type | SOIC-7 | |
| Bias-Supply Voltage Range | 9-35 | V |
| Minimum Switching Frequency | 170 | Hz |
| Overvoltage Threshold | 4.52-4.71 | V |
| Overcurrent Threshold | 1.4-1.6 | V |
Key Features
- Optocoupled feedback for constant-voltage regulation and primary-side regulation (PSR) for constant-current regulation.
- Internal 700-V startup switch for ultra-low standby power.
- Resonant-ring valley-switching operation for highest overall efficiency.
- Frequency dithering to ease EMI compliance.
- Clamped gate-drive output for MOSFET.
- Overvoltage, low-line, and overcurrent protection functions.
- Discontinuous conduction mode (DCM) with valley-switching to reduce switching losses.
- Modulation of switching frequency and primary current-peak amplitude (FM and AM) for high conversion efficiency.
- SOIC-7 package.
- Support for custom design using the WEBENCH® Power Designer tool.
Applications
- USB-compliant adapters and chargers for consumer electronics such as smartphones, tablet computers, and cameras.
- Standby supply for TVs and desktop computers.
- White goods and other high-power-density charger designs.
Q & A
- What is the primary function of the UCC28740DR?
The UCC28740DR is a Constant-Voltage, Constant-Current (CVCC) Flyback controller designed for high-performance power supply applications.
- What is the maximum switching frequency of the UCC28740DR?
The maximum switching frequency is 100 kHz.
- How does the UCC28740DR achieve low standby power?
The device achieves ultra-low standby power through an internal 700-V startup switch, dynamically controlled operating states, and a tailored modulation profile.
- What protection features does the UCC28740DR include?
The device includes overvoltage, low-line, and overcurrent protection functions, as well as internal overtemperature protection.
- What is the package type of the UCC28740DR?
The UCC28740DR is packaged in a SOIC-7 package.
- What is the voltage regulation accuracy of the UCC28740DR?
The voltage regulation accuracy is ±1% across line and load.
- What is the current regulation accuracy of the UCC28740DR?
The current regulation accuracy is ±5% across line and load.
- How does the UCC28740DR reduce EMI?
The device reduces EMI through frequency dithering and resonant-ring valley-switching operation.
- Can the UCC28740DR be used for custom designs?
- What are some common applications of the UCC28740DR?
