Overview
The NCP1236BD100R2G is a fixed-frequency current-mode controller designed by onsemi for use in 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 the 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, thanks to its frequency foldback and skip mode capabilities.
Key Specifications
| Parameter | Unit | Typical | Min | Max |
|---|---|---|---|---|
| Oscillator Frequency | kHz | 100 | 92 | 108 |
| VCC Supply Voltage | V | - | 8 | 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 to prevent sub-harmonic oscillations.
- Frequency Foldback and Skip Mode: For maximized performance in light load and standby conditions, reducing switching losses.
- Timer-Based Overload Protection: Available in latched or auto-recovery modes, with shortened overload timer for increased safety.
- High-Voltage Start-Up Current Source with Brown-Out Detection: Ensures clean start-up and dynamic self-supply, with protection against low input voltage.
- Adjustable Overpower Compensation: Allows adjustment of compensation based on the input voltage.
- Latch-Off Input for Severe Fault Conditions: Enables direct connection of an NTC for overtemperature protection.
- Internal Thermal Shutdown: Protects the device against self-overheating.
- Frequency Modulation for EMI Reduction: Includes internal frequency jittering to soften the EMI signature.
- Clamped Driver Stage: Safely clamps the DRV pin voltage below 16 V, reducing current consumption.
Applications
- AC-DC Adapters for Notebooks, LCD, and Printers
- Offline Battery Chargers
- Consumer Electronic Power Supplies
- Auxiliary/Housekeeping Power Supplies
Q & A
- What is the primary function of the NCP1236BD100R2G?
The NCP1236BD100R2G is a fixed-frequency current-mode controller designed for use in flyback converters.
- What is the Dynamic Self-Supply (DSS) feature?
The DSS feature activates an internal startup current source to supply the controller during transients, simplifying the design of the auxiliary supply and the VCC capacitor.
- What are the oscillator frequency options for the NCP1236?
The NCP1236 is available in 65 kHz and 100 kHz oscillator frequency options.
- How does the frequency foldback feature work?
The frequency foldback feature reduces the switching frequency to minimize losses in light load conditions, and it can enter a skip mode for extremely low load conditions.
- What is the purpose of the high-voltage start-up current source?
The high-voltage start-up current source ensures a clean start-up and provides dynamic self-supply to the controller if the VCC voltage transiently drops.
- How does the overload protection work?
The overload protection is timer-based and depends solely on the feedback signal. It can operate in latched or auto-recovery modes.
- What is the maximum VCC supply voltage for the NCP1236BD100R2G?
The maximum VCC supply voltage is 28 V, with an overvoltage threshold that latches the controller off.
- Does the NCP1236BD100R2G have thermal protection?
Yes, the device includes internal thermal shutdown to protect against self-overheating.
- How does the latch-off input work?
The latch-off input can be triggered by either an overvoltage or an overtemperature condition, allowing direct connection of an NTC for overtemperature protection.
- What is the soft-start time for the NCP1236BD100R2G?
The soft-start time is 4.0 ms, during which the peak current is gradually increased to minimize stress on power components.
