Overview
The NCP1280DR2G, produced by onsemi, is an Active Clamp Voltage Mode PWM Controller designed for off-line power converter applications. This controller integrates several advanced features to enhance the efficiency and reliability of power supplies. It includes a high voltage startup regulator, line under/overvoltage protection, soft-start, and dual mode overcurrent protection, among other features. The NCP1280DR2G is particularly suited for high-end desktop power supplies, industrial power supplies, and other applications requiring robust and efficient power conversion.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Input Line Voltage (Vin) | -0.3 | - | 700 | V |
| Auxiliary Supply Voltage (VAUX) | -0.3 | - | 18 | V |
| Auxiliary Supply Input Current (IAUX) | - | - | 35 | mA |
| Output Current (IOUT) | - | - | 10 | mA |
| Operating Junction Temperature (TJ) | -40 | - | 125 | °C |
| Storage Temperature Range (Tstg) | -55 | - | 150 | °C |
| Oscillator Frequency (fOSC1, RT = 101 kΩ) | 285 | 300 | 315 | kHz |
| Maximum Duty Cycle (DCMAX) | 57 | 75 | 85 | % |
| Soft-Start Charge Current (ISS(C)) | 5.0 | 6.2 | 7.4 | μA |
Key Features
- Internal High Voltage Startup Regulator: Up to 700 V capability, reducing the need for external startup components and enhancing system efficiency.
- Dual Control Outputs with Adjustable Overlap Delay: Allows control of primary switch and active clamp/reset switch or synchronous rectifier topology.
- Programmable Maximum Duty Cycle Control: Adjustable duty cycle to optimize converter performance.
- Single Resistor Oscillator Frequency Setting: Easy adjustment of oscillator frequency using a single resistor.
- Fast Line Feedforward: Compensates for line voltage changes, ensuring immediate duty cycle adjustments.
- Line Under/Overvoltage Lockout: Protects against undervoltage and overvoltage conditions with adjustable thresholds.
- Dual Mode Overcurrent Protection: Provides cycle-by-cycle and cycle skip current limiting for robust protection.
- Programmable Soft-Start: Gradual startup to prevent inrush currents and ensure smooth operation.
- Precision 5.0 V Reference: Stable voltage reference for accurate control and monitoring.
Applications
- Off-Line Power Converters: Suitable for converters in the 100-500 W range.
- Desktop Power Supplies (High-End): Ideal for high-performance desktop power supplies.
- Industrial Power Supplies: Used in various industrial power supply applications requiring high reliability and efficiency.
- Plasma/LCD TV Front-End: Applicable in the front-end power conversion stages of plasma and LCD TVs.
Q & A
- What is the maximum input voltage the NCP1280DR2G can handle?
The NCP1280DR2G can handle a maximum input voltage of 700 V.
- What is the purpose of the internal high voltage startup regulator?
The internal high voltage startup regulator eliminates the need for external startup components and enhances system efficiency by using power supplied by an auxiliary winding.
- How does the dual mode overcurrent protection work?
The dual mode overcurrent protection provides both cycle-by-cycle and cycle skip current limiting to ensure robust protection against overcurrent conditions.
- What is the function of the fast line feedforward feature?
The fast line feedforward feature compensates for changes in line voltage, allowing immediate adjustments to the duty cycle.
- How is the oscillator frequency set in the NCP1280DR2G?
The oscillator frequency can be set using a single resistor (RT) connected to the oscillator pin.
- What is the purpose of the soft-start feature?
The soft-start feature allows a gradual startup to prevent inrush currents and ensure smooth operation of the converter.
- How does the line under/overvoltage lockout work?
The line under/overvoltage lockout protects against undervoltage and overvoltage conditions with adjustable thresholds, and the overvoltage function can be disabled if necessary.
- What are the typical applications of the NCP1280DR2G?
The NCP1280DR2G is typically used in off-line power converters, high-end desktop power supplies, industrial power supplies, and plasma/LCD TV front-end applications.
- What is the operating junction temperature range of the NCP1280DR2G?
The operating junction temperature range is from -40°C to 125°C.
- How does the active clamp topology benefit the converter design?
The active clamp topology reduces voltage stress on the main switch, allowing the use of lower voltage MOSFETs, which can lower system cost and increase efficiency.
