Overview
The NCP1250BP65G, produced by onsemi, is a highly integrated current-mode PWM controller designed for offline power supplies. It offers robust performance and is packaged in a compact TSOP-6 or PDIP-8 format. This controller is ideal for applications requiring low part count and cost-effectiveness, particularly in low-cost ac-dc adapters and open-frame power supplies. It operates at a fixed frequency of 65 kHz and features advanced protection mechanisms such as Over Power Protection (OPP), Over Voltage Protection (OVP), and short-circuit protection.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| VCC Power Supply Voltage | 28 | V |
| Maximum DRV Pin Voltage | VCC + 0.3 | V |
| Maximum Voltage on Low Power Pins (CS, FB, OPP) | -0.3 to 10 | V |
| Maximum Junction Temperature | 150 | °C |
| Storage Temperature Range | -60 to +150 | °C |
| Oscillation Frequency (65 kHz version) | 61 to 71 | kHz |
| VCCON (VCC increasing level) | 16 to 20 | V |
| VCC(min) (VCC decreasing level) | 8.2 to 9.4 | V |
| Internal Soft-Start Duration | 4.0 ms | ms |
| Propagation Delay from Current Detection to Gate Off-State | 100 to 150 ns | ns |
Key Features
- Fixed-Frequency 65 kHz Current-Mode Control Operation: The NCP1250 operates at a fixed frequency, ensuring stable and efficient power supply operation.
- Internal and Adjustable Over Power Protection (OPP) Circuit: This feature allows for non-dissipative OPP, enhancing the controller's performance and reliability.
- Frequency Foldback Down to 26 kHz and Skip-Cycle in Light Load Conditions: The controller adjusts its switching frequency and enters skip-cycle mode to optimize efficiency under light load conditions.
- Internal Ramp Compensation: Eliminates sub-harmonic oscillations with a simple resistor in series with the current-sense information.
- Internal Fixed 4 ms Soft-Start: Reduces inrush current during startup, ensuring smooth operation.
- 100 ms Timer-Based Auto-Recovery Short-Circuit Protection: Provides robust protection against short-circuit conditions.
- Frequency Jittering in Normal and Frequency Foldback Modes: Improves EMI signature by spreading out energy in conducted noise analysis.
- Option for Auto-Recovery or Latched Short-Circuit Protection: Offers flexibility in handling short-circuit events.
- OVP Input for Improved Robustness: Protects the circuit against overvoltage conditions.
- Up to 28 V VCC Operation: Supports a wide range of input voltages.
- +300 mA/−500 mA Source/Sink Drive Capability: Provides strong drive capability for external MOSFETs.
- Less than 100 mW Standby Power at High Line: Ensures low no-load standby power, making it suitable for energy-efficient designs.
- EPS 2.0 Compliant: Meets the Energy Star Program Requirements for Efficiency.
Applications
- ac-dc Converters for TVs, Set-top Boxes, and Printers
- Offline Adapters for Notebooks and Netbooks
- Low-Cost ac-dc Adapters
- Open-Frame Power Supplies
Q & A
- What is the operating frequency of the NCP1250BP65G?
The NCP1250BP65G operates at a fixed frequency of 65 kHz.
- What is the maximum VCC power supply voltage for the NCP1250BP65G?
The maximum VCC power supply voltage is 28 V.
- How does the NCP1250BP65G handle over power protection (OPP)?
The NCP1250BP65G features an internal and adjustable OPP circuit, allowing for non-dissipative OPP through a simple resistive divider on the OPP pin.
- What is the purpose of frequency foldback in the NCP1250BP65G?
The frequency foldback reduces the switching frequency down to 26 kHz and enters skip-cycle mode under light load conditions to optimize efficiency.
- How does the NCP1250BP65G protect against short-circuit conditions?
The controller features a 100 ms timer-based auto-recovery short-circuit protection, offering robust protection against short-circuit events.
- What is the significance of internal ramp compensation in the NCP1250BP65G?
The internal ramp compensation eliminates sub-harmonic oscillations, ensuring stable operation by summing the sensed current with a ramp signal.
- How does the NCP1250BP65G improve EMI performance?
The controller uses frequency jittering to spread out energy in conducted noise analysis, improving the EMI signature.
- What are the typical applications of the NCP1250BP65G?
Typical applications include ac-dc converters for TVs, set-top boxes, and printers, as well as offline adapters for notebooks and netbooks.
- Is the NCP1250BP65G compliant with any energy efficiency standards?
Yes, the NCP1250BP65G is EPS 2.0 compliant, meeting the Energy Star Program Requirements for Efficiency.
- What is the standby power consumption of the NCP1250BP65G at high line?
The standby power consumption is less than 100 mW at high line, ensuring low no-load standby power.
