Overview
The NCP1256BSN65T1G is a low-power offline PWM current mode controller produced by onsemi. This component is designed to build cost-effective switch-mode power supplies, ranging from a few watts to several tens of watts. It is housed in a compact TSOP-6 package and can be supplied up to 30 V. The NCP1256BSN65T1G operates at a fixed frequency of 65 kHz and features advanced protection mechanisms and efficiency enhancements, making it an ideal choice for low-cost ac-dc adapters, auxiliary power supplies, and other similar applications.
Key Specifications
| Symbol | Description | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| VCCON | VCC increasing level at which driving pulses are authorized | 16 | 18 | 20 | V |
| VCC(min) | VCC decreasing level at which driving pulses are stopped | 8.3 | 8.9 | 9.5 | V |
| VCCHYST | Hysteresis VccON−Vcc(min) | 8.4 | - | 9.25 | V |
| ICC1 | Start-up current | 5 | 7.5 | - | μA |
| fOSC,nom | Oscillation Frequency (65 kHz version) | 61 | 65 | 70 | kHz |
| Dmax | Maximum duty ratio | 77 | 80 | 83 | % |
| fjitter | Frequency jittering in percentage of fOSC | - | - | ±5 | % |
Key Features
- Fixed-frequency 65 kHz Current-mode Control Operation: The NCP1256BSN65T1G operates at a fixed frequency of 65 kHz, ensuring stable and efficient power supply operation.
- Adjustable Over Power Protection (OPP) Circuit: The OPP circuit is adjustable and disabled at low line conditions, providing flexible protection against over-power events.
- Adjustable Brown Out Level: The brown-out level can be adjusted, allowing for customization based on the specific application requirements.
- Frequency Foldback and Skip-cycle in Light Load Conditions: The controller reduces its switching frequency down to 26 kHz and enters skip-cycle mode in light load conditions to improve efficiency.
- Internally-fixed Slope Compensation Ramp: An internal slope compensation signal is included to cover most offline design cases.
- Internally-fixed 4 ms Soft-start: A soft-start mechanism is integrated to prevent power switch stress and reduce output voltage overshoots during startup.
- 70 ms Timer-based Auto-recovery Short-circuit Protection: The controller features a timer-based auto-recovery short-circuit protection mechanism.
- Frequency Jittering in Normal and Frequency Foldback Modes: Frequency jittering helps in spreading out energy in conducted noise analysis, improving EMI performance.
- Double Hiccup Auto-recovery Short-circuit Protection: The controller can enter a double-hiccup auto-recovery mode in case of short-circuit events.
- Latched/Auto-Recovery OVP Protection on Vcc: The controller includes latched or auto-recovery OVP protection on the Vcc pin.
- Latched Inputs for Improved Robustness (OVP and OTP implementations): Two independent latch inputs are provided for OVP and OTP implementations.
- +500 mA/ −500 mA Source/Sink Drive Capability: The driver output has a +500 mA/ −500 mA source/sink drive capability.
- EPS 2.0 Compliant and Pb-Free Devices: The NCP1256BSN65T1G is EPS 2.0 compliant and is a Pb-free device.
Applications
- Ac-dc Adapters for Portable Devices, Computers, Tablets, etc.: Ideal for power supplies in portable devices and computing equipment.
- Auxiliary Power Supplies: Suitable for auxiliary power supplies in various electronic systems.
- Open-Frame Power Supplies: Used in open-frame power supplies where low part-count and cost-effectiveness are crucial.
Q & A
- What is the operating frequency of the NCP1256BSN65T1G?
The NCP1256BSN65T1G operates at a fixed frequency of 65 kHz.
- What is the maximum duty ratio of the NCP1256BSN65T1G?
The maximum duty ratio is 83%.
- How does the frequency foldback feature work in the NCP1256BSN65T1G?
The controller reduces its switching frequency down to 26 kHz and enters skip-cycle mode in light load conditions to improve efficiency.
- What is the purpose of the soft-start mechanism in the NCP1256BSN65T1G?
The soft-start mechanism prevents power switch stress and reduces output voltage overshoots during startup.
- What protection mechanisms are included in the NCP1256BSN65T1G?
The controller includes timer-based auto-recovery short-circuit protection, adjustable over power protection (OPP), brown-out protection, and latched/auto-recovery OVP protection.
- How does the frequency jittering feature improve EMI performance?
Frequency jittering helps in spreading out energy in conducted noise analysis, improving EMI performance.
- What is the drive capability of the driver output in the NCP1256BSN65T1G?
The driver output has a +500 mA/ −500 mA source/sink drive capability.
- Is the NCP1256BSN65T1G compliant with any specific standards?
Yes, it is EPS 2.0 compliant.
- What is the package type of the NCP1256BSN65T1G?
The NCP1256BSN65T1G is housed in a TSOP-6 package.
- What are the typical applications of the NCP1256BSN65T1G?
Typical applications include ac-dc adapters for portable devices, auxiliary power supplies, and open-frame power supplies.
