Overview
The NCP1234BD65R2G is a fixed-frequency current-mode controller designed by onsemi for use in flyback converters. This device is part of the NCP1234 family and is known for its high efficiency, low standby power consumption, and robust protection features. It is pin-to-pin compatible with the previous NCP12xx families, making it an excellent choice for upgrading existing designs. The NCP1234BD65R2G features Dynamic Self-Supply (DSS), which simplifies the design of the auxiliary supply and VCC capacitor, and includes internal frequency jittering to improve EMI performance.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Switching Frequency | 65 kHz | |
| Maximum Duty Cycle | 80% | |
| VCC Operation Range | 9.5 to 28 V | V |
| Peak Source/Sink Current Drive Capability | ±500 mA | mA |
| High Voltage Pin Range | -0.3 to 500 V | V |
| Operating Junction Temperature Range | -40 to +125 °C | °C |
| Package Type | SOIC-7 | |
| ESD Capability (Human Body Model) | 2000 V | V |
Key Features
- Fixed-Frequency Current-Mode Operation with Built-In Ramp Compensation: Ensures stable operation and prevents sub-harmonic oscillations.
- Frequency Foldback and Skip Mode: Maximizes performance in light load and standby conditions.
- Timer-Based Overload Protection: Available in latched (option A) or auto-recovery (option B) operation, independent of auxiliary winding.
- Dynamic Self-Supply (DSS): Simplifies the design of the auxiliary supply and VCC capacitor.
- Frequency Modulation for EMI Reduction: Includes frequency jittering to soften the EMI signature.
- Adjustable Overpower Compensation: Helps maintain maximum power independent of input voltage.
- Latch-Off Input for Severe Fault Conditions: Allows direct connection of an NTC for overtemperature protection.
- Soft-Start and Internal Thermal Shutdown: Minimizes stress on power components during start-up and protects against self-overheating.
Applications
- AC-DC Adapters for Notebooks, LCD, and Printers: Ideal for compact and efficient power supply designs.
- Offline Battery Chargers: Suitable for charging various battery types with high efficiency.
- Consumer Electronic Power Supplies: Used in a wide range of consumer electronics requiring reliable and efficient power conversion.
- Auxiliary/Housekeeping Power Supplies: Provides power for auxiliary circuits in larger systems.
Q & A
- What is the switching frequency of the NCP1234BD65R2G?
The switching frequency is 65 kHz.
- What is the maximum duty cycle of the DRV pin?
The maximum duty cycle is 80% with an accuracy of ±7%.
- What is the VCC operation range of the NCP1234BD65R2G?
The VCC operation range is from 9.5 to 28 V.
- What is the peak source/sink current drive capability of the device?
The peak source/sink current drive capability is ±500 mA.
- How does the Dynamic Self-Supply (DSS) function work?
The DSS function activates the internal startup current source to supply the controller during transients, simplifying the design of the auxiliary supply and VCC capacitor.
- What type of overload protection does the NCP1234BD65R2G offer?
The device offers timer-based overload protection that can be configured for latched or auto-recovery operation.
- How does the frequency jittering feature help with EMI?
The frequency jittering feature spreads out the energy content of frequency peaks, helping to improve the EMI signature.
- What is the purpose of the latch-off input?
The latch-off input allows the controller to be latched off by an overvoltage or overtemperature condition, using an NTC for direct connection.
- What is the soft-start period of the NCP1234BD65R2G?
The soft-start period is 4.0 ms, during which the peak current is gradually increased to minimize stress on power components.
- What is the operating junction temperature range of the device?
The operating junction temperature range is from -40 to +125 °C.
