Overview
The NCP1338DR2G, produced by onsemi, is a PWM Current-Mode Controller designed for free-running quasi-resonant operation. This controller combines a true current-mode modulator and a demagnetization detector, ensuring full Borderline/Critical Conduction Mode in various load and line conditions. It features minimum drain voltage switching and quasi-resonant operation, which reduces primary switch turn-on losses and secondary diode recovery losses, thereby minimizing EMI and video noise perturbations.
Key Specifications
| Parameter | Min | |||
|---|---|---|---|---|
| Power Supply Voltage (VCC) | 9 | 12 | 18.6 | V |
| Maximum Junction Temperature (TJMAX) | 150 | °C | ||
| Operating Temperature Range | -40 | 125 | °C | |
| Storage Temperature Range | -60 | 150 | °C | |
| Maximum Frequency | 130 | kHz | ||
| Minimum Switching Frequency in Soft-Skip Mode | 25 | kHz | ||
| Output Voltage Rise-Time @ CL = 1.0 nF | 50 | ns | ||
| Output Voltage Fall-Time @ CL = 1.0 nF | 20 | ns | ||
| Source Resistance | 20 | Ω | ||
| Sink Resistance | 8.0 | Ω | ||
| Temperature Shutdown | 130 | °C |
Key Features
- Free-Running Borderline/Critical Mode Quasi-Resonant Operation: Ensures valley-switching operation under all conditions, reducing EMI and video noise perturbations.
- Current-Mode Modulation: With internal demagnetization detection for efficient switching.
- Soft-Skip Mode: Enters skip mode under low load conditions to minimize switching frequency and noise.
- Auto-Recovery Short-Circuit Protection: Independent of auxiliary voltage, with a fault timer and soft burst mode for restart attempts.
- Overvoltage Protection (OVP): Stops switching when an overvoltage condition is detected).
- Brown-Out Protection: Monitors the input voltage level to protect against low mains conditions).
- Dynamic Self-Supply (DSS): Allows direct connection to the high-voltage DC rail, eliminating the need for an auxiliary winding in low-power applications).
- Internal 4.0 ms Soft-Start: Reduces startup stress and noise).
- Internal Temperature Shutdown: Protects the device from overheating).
- Direct Optocoupler Connection: Simplifies feedback loop implementation).
Applications
- Offline Battery Chargers: Suitable for efficient and reliable battery charging systems).
- Consumer Electronics: Ideal for devices such as DVD players, set-top boxes, and TVs).
- Auxiliary Power Supplies: Used in USB chargers, appliances, and other auxiliary power supply applications).
- Low-Cost AC-DC Adapters: Optimized for low part-count and high reliability in cost-sensitive applications).
Q & A
- What is the primary function of the NCP1338DR2G?
The NCP1338DR2G is a PWM Current-Mode Controller designed for free-running quasi-resonant operation in switch-mode power supplies (SMPS)).
- What are the key benefits of quasi-resonant operation in the NCP1338DR2G?
Quasi-resonant operation reduces primary switch turn-on losses, secondary diode recovery losses, EMI, and video noise perturbations).
- How does the Soft-Skip mode operate in the NCP1338DR2G?
The Soft-Skip mode is activated under low load conditions, stopping output pulses and restarting when the feedback loop forces a higher setpoint, ensuring noise-free operation).
- What is the purpose of the Dynamic Self-Supply (DSS) feature?
The DSS feature allows the controller to be directly connected to the high-voltage DC rail, eliminating the need for an auxiliary winding in low-power applications).
- How does the NCP1338DR2G protect against overcurrent conditions?
The device features an auto-recovery short-circuit protection that disables output pulses and enters a soft burst mode to restart the SMPS after the fault has cleared).
- What is the role of the brown-out protection in the NCP1338DR2G?
The brown-out protection monitors the input voltage level to protect the SMPS against low mains conditions, ensuring safe operation).
- What is the maximum junction temperature for the NCP1338DR2G?
The maximum junction temperature is 150°C).
- How does the internal temperature shutdown protect the device?
The internal temperature shutdown protects the device by stopping operation when the temperature exceeds 130°C, with a hysteresis of 30°C).
- What is the purpose of the internal 4.0 ms soft-start feature?
The internal 4.0 ms soft-start reduces startup stress and noise, ensuring a smooth startup sequence).
- Can the NCP1338DR2G be used in consumer electronics?
Yes, the NCP1338DR2G is suitable for use in consumer electronics such as DVD players, set-top boxes, and TVs).
