Overview
The NCP1253BSN65T1G is a highly integrated PWM (Pulse Width Modulation) controller designed by onsemi for offline power supplies. It is packaged in a compact TSOP-6 package, making it ideal for space-constrained applications. This controller operates in peak current mode control with a fixed switching frequency of 65 kHz and features frequency foldback and skip-cycle capabilities to optimize performance under light load conditions. The NCP1253BSN65T1G is engineered to provide rugged and high-performance operation, with a supply voltage range up to 28 V.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Supply Voltage (VCC) | 5 - 28 | V |
| Switching Frequency | 65 kHz | kHz |
| Frequency Foldback | Down to 26 kHz | kHz |
| Maximum Junction Temperature | 150 | °C |
| Storage Temperature Range | -60 to +150 | °C |
| ESD Capability (Human Body Model) | 2 kV | V |
| ESD Capability (Machine Model) | 200 V | V |
| Internal Soft-Start Duration | 4 ms | ms |
| Maximum Duty Ratio | 76 - 84 % | % |
| Latched Overvoltage Protection on VCC | 24 - 27 V | V |
Key Features
- Fixed-Frequency Operation: The NCP1253BSN65T1G operates at a fixed frequency of 65 kHz or 100 kHz in peak current mode control.
- Frequency Foldback and Skip-Cycle: The controller reduces its switching frequency down to 26 kHz and enters skip-cycle mode under light load conditions to minimize standby power.
- Adjustable Slope Compensation: Allows for the compensation of sub-harmonic oscillations through the inclusion of a simple resistor in the current sense signal.
- Low Startup Current: The controller has a low startup current of less than 15 μA, facilitating the design of low standby power adapters.
- EMI Jittering: An internal low-frequency modulation signal helps in spreading out energy in conducted noise analysis, improving EMI signature.
- Short-Circuit Protection: Features timer-based auto-recovery or latched short-circuit protection to handle overloads and short circuits effectively.
- Over Voltage Protection (OVP): Protects the circuit by latching off when the VCC voltage exceeds 25.5 V.
- Extremely Low No-Load Standby Power: Optimized for low power consumption during standby mode.
Applications
- AC-DC converters for TVs, set-top boxes, and printers.
- Offline adapters for notebooks and netbooks.
- Low-cost AC-DC adapters and open-frame power supplies.
Q & A
- What is the primary function of the NCP1253BSN65T1G?
The NCP1253BSN65T1G is a PWM controller designed for offline power supplies, operating in peak current mode control.
- What are the available switching frequencies for the NCP1253BSN65T1G?
The controller operates at fixed frequencies of 65 kHz or 100 kHz.
- How does the NCP1253BSN65T1G handle light load conditions?
The controller reduces its switching frequency down to 26 kHz and enters skip-cycle mode to minimize standby power under light load conditions.
- What is the purpose of the adjustable slope compensation feature?
The adjustable slope compensation helps in avoiding sub-harmonic oscillations by introducing a simple resistor in the current sense signal.
- What is the maximum junction temperature for the NCP1253BSN65T1G?
The maximum junction temperature is 150°C.
- How does the NCP1253BSN65T1G protect against overvoltage conditions?
The controller features latched overvoltage protection on the VCC pin, which stops the pulses and latches off when the VCC voltage exceeds 25.5 V.
- What is the startup current of the NCP1253BSN65T1G?
The startup current is less than 15 μA.
- How does the EMI jittering feature work?
An internal low-frequency modulation signal varies the oscillator frequency to spread out energy in conducted noise analysis, improving the EMI signature.
- What types of protection does the NCP1253BSN65T1G offer against short circuits?
The controller offers timer-based auto-recovery or latched short-circuit protection.
- In which package is the NCP1253BSN65T1G available?
The controller is available in a TSOP-6 package.
