Overview
The NCP1239JD65R2G is a fixed-frequency current-mode controller designed by onsemi for use in flyback converters. This component is part of the NCP1239 family and is distinguished by its high-voltage start-up current source, which enables a quick and lossless power-on sequence. This feature simplifies the design of the auxiliary supply and the VCC capacitor, making it an ideal choice for low-cost AC-DC adapters and open-frame power supplies.
Key Specifications
| Parameter | Symbol | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| Power Supply Voltage, VCC Pin, Continuous | VCC | -0.3 | 35 | V | |
| Maximum Voltage on Low Power Pins (CS, FB, Fault) | -0.3 | 5.5 | V | ||
| Maximum Voltage on DRV Pin | VDRV | -0.3 | 20 | V | |
| High Voltage Pin (HV) | -0.3 | 650 | V | ||
| Switching Frequency | fSW | 65 kHz | kHz | ||
| Frequency Foldback | fTRANS | 22 | 26 | 30 | kHz |
| Internal IC Consumption in Normal Operation | ICC2 | 3.1 | 4.0 | mA | |
| Peak Source Current (DRV High State) | ISOURCE | 500 | mA | ||
| Maximum Junction Temperature | TJ(max) | 150 | °C |
Key Features
- Fixed-Frequency Operation: The NCP1239JD65R2G operates at a fixed frequency of 65 kHz, with frequency foldback down to 26 kHz and skip mode to maximize performance in light load conditions.
- High-Voltage Start-Up Current Source: Provides a quick and lossless power-on sequence, simplifying the design of the auxiliary supply and VCC capacitor.
- Adjustable Over Power Protection (OPP): Non-dissipative OPP circuit for enhanced protection.
- Brown-Out (BO) Detection: Integrated BO detection for robust operation.
- Internal Slope Compensation and Soft-Start: Ensures stable operation and reduces stress on components during start-up.
- Frequency Jittering: Implemented in both normal and frequency foldback modes to reduce EMI.
- Short-Circuit Protection: 64-ms timer-based short-circuit protection with auto-recovery or latched operation.
- Over-Voltage Protection (OVP) and Over-Temperature Protection (OTP): Latched OVP on VCC and OTP input for improved robustness.
- Internal Thermal Shutdown: Protects the device from overheating.
- Low No-Load Standby Power: Extremely low power consumption in standby mode.
Applications
The NCP1239JD65R2G is particularly suited for low-cost AC-DC adapters, open-frame power supplies, and other applications where low part count and cost effectiveness are critical. It is also suitable for various power supply designs requiring high efficiency and robust protection features.
Q & A
- What is the switching frequency of the NCP1239JD65R2G?
The NCP1239JD65R2G operates at a fixed frequency of 65 kHz.
- What is the purpose of the high-voltage start-up current source?
The high-voltage start-up current source provides a quick and lossless power-on sequence, simplifying the design of the auxiliary supply and VCC capacitor.
- What protection features does the NCP1239JD65R2G include?
The device includes adjustable over power protection (OPP), brown-out (BO) detection, over-voltage protection (OVP), over-temperature protection (OTP), and internal thermal shutdown.
- How does the frequency foldback feature work?
The frequency foldback feature reduces the switching frequency down to 26 kHz as the power on the secondary side decreases, and the part enters skip cycle mode to maximize efficiency in light load conditions.
- What is the maximum junction temperature for the NCP1239JD65R2G?
The maximum junction temperature is 150°C.
- What is the peak source current capability of the DRV pin?
The peak source current capability of the DRV pin is 500 mA.
- Does the NCP1239JD65R2G have internal slope compensation and soft-start features?
Yes, the device includes internal slope compensation and a fixed soft-start feature to ensure stable operation and reduce stress on components during start-up.
- How does the short-circuit protection work?
The device features a 64-ms timer-based short-circuit protection with auto-recovery or latched operation.
- What is the purpose of the fault pin?
The fault pin allows for fault detection and triggers a latch if the voltage exceeds the fault thresholds.
- What are the typical applications for the NCP1239JD65R2G?
The device is typically used in low-cost AC-DC adapters, open-frame power supplies, and other power supply designs requiring high efficiency and robust protection features.
