Overview
The NCP1236AD65R2G is a fixed-frequency current-mode controller designed by onsemi, specifically tailored for flyback converters. This device is part of the NCP1236 family and is pin-to-pin compatible with the previous NCP12xx series. It features Dynamic Self-Supply (DSS), which simplifies the design of the auxiliary supply and VCC capacitor by activating an internal startup current source during transients. The controller is optimized for high efficiency in light load conditions and low standby power consumption, making it an excellent choice for applications where component cost is a key constraint.
Key Specifications
| Parameter | Unit | Min | Max | |
|---|---|---|---|---|
| Oscillator Frequency | kHz | 65 | - | - |
| Minimum Switching Frequency | kHz | 22 | 27 | 32 |
| Feedback Voltage Threshold for Frequency Foldback Start | V | 1.22 | 1.35 | 1.48 |
| Feedback Voltage Threshold for Frequency Foldback Complete | V | 1.8 | 2.0 | 2.2 |
| VCC Operation Range | V | - | - | 28 |
| Peak Source / Sink Current Drive Capability | mA | - | - | 500 |
| Soft-Start Time | ms | - | 4.0 | - |
| Operating Temperature Range | °C | -40 | - | 125 |
| Package Type | - | - | - | SOIC-7 |
Key Features
- Fixed-Frequency Current-Mode Operation with Built-In Ramp Compensation: Ensures maximum safety 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 or auto-recovery modes, with shortened overload timer for increased safety.
- High-Voltage Current Source with Brown-Out Detection and Dynamic Self-Supply: Simplifies the design of the VCC capacitor and ensures clean start-up.
- Frequency Modulation for Softened EMI Signature: Helps in passing EMI limits by spreading out the energy content of frequency peaks.
- Adjustable Overpower Compensation: Allows adjustment of the amount of compensation based on the input voltage.
- Latch-Off Input for Severe Fault Conditions: Allows direct connection of an NTC for overtemperature protection.
- VCC Operation up to 28 V with Overvoltage Detection: Ensures safe operation within a wide VCC range.
- Internal Thermal Shutdown: Protects the device against self-overheating.
- Pin-to-Pin Compatibility with Existing NCP12xx Series: Facilitates easy migration and design.
- Pb-Free, Halogen Free/BFR Free, and RoHS Compliant: Meets environmental and safety standards.
Applications
- AC-DC Adapters for Notebooks, LCD, and Printers: Ideal for compact and efficient power supply designs.
- Offline Battery Chargers: Suitable for charging applications requiring high efficiency and safety features.
- Consumer Electronic Power Supplies: Used in a variety of consumer electronics where low component count and high safety are crucial.
- Auxiliary/Housekeeping Power Supplies: Applicable in systems requiring reliable and efficient auxiliary power.
Q & A
- What is the primary function of the NCP1236AD65R2G?
The NCP1236AD65R2G is a fixed-frequency current-mode controller designed for flyback converters, ensuring efficient and safe power supply operation.
- What is the Dynamic Self-Supply (DSS) feature?
The DSS feature activates the internal startup current source to supply the controller during transients, simplifying the design of the auxiliary supply and VCC capacitor.
- What are the oscillator frequency options for the NCP1236AD65R2G?
The NCP1236AD65R2G is available with an oscillator frequency of 65 kHz or 100 kHz.
- How does the frequency foldback feature work?
The frequency foldback feature reduces the switching frequency to minimize losses in light load conditions, and it transitions to skip mode for extremely low load conditions.
- What is the purpose of the high-voltage current source with brown-out detection?
The high-voltage current source ensures clean start-up and features brown-out detection to turn the controller off if the input voltage is too low.
- How does the adjustable overpower compensation work?
The adjustable overpower compensation converts the high input voltage sensed on the HV pin into a current, allowing for adjustable offset on the current sense voltage based on the input voltage.
- What is the soft-start time of the NCP1236AD65R2G?
The soft-start time is 4.0 ms, during which the peak current is gradually increased to minimize stress on power components.
- What is the operating temperature range of the NCP1236AD65R2G?
The operating temperature range is from -40°C to +125°C.
- Is the NCP1236AD65R2G RoHS compliant?
Yes, the NCP1236AD65R2G is Pb-Free, Halogen Free/BFR Free, and RoHS compliant.
- What are some typical applications of the NCP1236AD65R2G?
Typical applications include AC-DC adapters, offline battery chargers, consumer electronic power supplies, and auxiliary/housekeeping power supplies.
