Overview
The UCC2894DR is a 16V active clamp current mode PWM controller produced by Texas Instruments. It is part of the UCC2891/2/3/4 family, designed to simplify the implementation of various active clamp/reset switching power topologies. This controller features a peak current-mode, fixed-frequency operation and includes the logic and drive capability for the auxiliary switch, allowing for precise programming of critical delays for proper active clamp operation.
The UCC2894DR is packaged in a 16-pin SOIC (D) package and operates over a temperature range of -40°C to 85°C. It includes a range of features such as low output jitter, soft-stop shutdown, and a 1.0-MHz synchronizable oscillator, making it suitable for high-efficiency, low EMI/RFI off-line or DC/DC converters.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Line Input Voltage (VIN) | 18 | - | 110 | V |
| Supply Voltage (VDD) | 8.5 | 12.0 | 16.0 | V |
| Operating Junction Temperature (TJ) | -40 | - | 105 | °C |
| Oscillator Frequency (fOSC) | 237 | 250 | 263 | kHz |
| Maximum Duty Cycle | 66% | 70% | 74% | % |
| Current Sense Threshold (VCS) | 1.23 | 1.27 | 1.31 | V |
| Rise Time (tR) | 19 | 28 | - | ns |
| Fall Time (tF) | 14 | 23 | - | ns |
Key Features
- Low Output Jitter
- Soft-Stop Shutdown of MAIN and AUX
- Ideal for Active Clamp/Reset Forward, Flyback Converters
- Provides Complementary Auxiliary Driver with Programmable Deadtime (Turn-On Delay) between AUX and MAIN Switches
- Peak Current-Mode Control with Cycle-by-Cycle Current Limiting
- TrueDrive™ 2-A Sink, 2-A Source Outputs
- Accurate Line UV and Line OV Threshold
- Programmable Slope Compensation
- 1.0-MHz Synchronizable Oscillator
- Precise Programmable Maximum Duty Cycle
- Programmable Soft Start
Applications
- 150-W to 700-W SMPS
- High-Efficiency, Low EMI/RFI Off-Line or DC/DC Converters
- Server, 48-V Telecom, Datacom
- High Power Adapter, LCD-TV and PDP-TV
Q & A
- What is the operating temperature range of the UCC2894DR?
The operating temperature range is -40°C to 85°C.
- What is the typical oscillator frequency of the UCC2894DR?
The typical oscillator frequency is 250 kHz.
- What is the maximum duty cycle of the UCC2894DR?
The maximum duty cycle is up to 74%.
- What type of current-mode control does the UCC2894DR use?
The UCC2894DR uses peak current-mode control with cycle-by-cycle current limiting.
- What are the key applications of the UCC2894DR?
Key applications include 150-W to 700-W SMPS, high-efficiency off-line or DC/DC converters, server, 48-V telecom, datacom, and high power adapters for LCD-TV and PDP-TV.
- How is the soft-start time programmed in the UCC2894DR?
The soft-start time is programmed by a capacitor (CSS) connected between the SS/SD pin and GND, which is charged by a precise internal DC current source.
- What is the purpose of the LINEUV pin in the UCC2894DR?
The LINEUV pin monitors the incoming power source to provide an accurate undervoltage lockout function with user-programmable hysteresis.
- How is the oscillator frequency set in the UCC2894DR?
The oscillator frequency is set using the RTON and RTOFF pins, which control the charge and discharge currents of the internal timing capacitor.
- What is the role of the TrueDrive™ outputs in the UCC2894DR?
The TrueDrive™ outputs provide 2-A sink and 2-A source capabilities, ensuring high-current drive for the external MOSFETs.
- How is slope compensation programmed in the UCC2894DR?
Slope compensation is programmed using the RSLOPE pin, which allows for precise adjustment of the slope compensation.
