Overview
The NCP1207APG, 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 to ensure full borderline/critical conduction mode in various load and line conditions. It features high-voltage technology, allowing direct connection to the high-voltage DC rail, and includes several protective and operational enhancements such as Dynamic Self-Supply (DSS), Overvoltage Protection (OVP), and Overcurrent Protection (OCP).
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| VCC Increasing Level at which the Current Source Turns-off | 10.8 | 12 | 12.9 | V |
| VCC Decreasing Level at which the Current Source Turns-on | 9.1 | 10 | 10.6 | V |
| Internal Soft-start Time | - | 1.0 | - | ms |
| Minimum TOFF (Internal Blanking Delay after TON) for NCP1207A | 8.0 | - | - | μs |
| Minimum TOFF (Internal Blanking Delay after TON) for NCP1207B | 4.5 | - | - | μs |
| Peak Current Source/Sink Capability | - | 500 | - | mA |
| Undervoltage Lockout for VCC | - | 10 | - | V |
| Maximum Voltage on Pin 8 (HV) | - | - | 500 | V |
| ESD Capability (Human Body Model) | - | - | 2000 | V |
Key Features
- Free-Running Borderline/Critical Mode Quasi-Resonant Operation
- Current-Mode with Adjustable Skip-Cycle Capability
- No Auxiliary Winding VCC Operation due to Dynamic Self-Supply (DSS)
- Auto-Recovery Overcurrent Protection
- Latching Overvoltage Protection
- External Latch Triggering (e.g., via Overtemperature Signal)
- Internal 1.0 ms Soft-Start
- Internal Temperature Shutdown
- Direct Optocoupler Connection
- SPICE Models Available for Transient Analysis
- Pb-Free and Halide-Free Devices
Applications
The NCP1207APG is particularly suited for applications where low part-count and high reliability are crucial. Typical applications include:
- Low-cost AC/DC adapters
- Consumer electronics
- Auxiliary power supplies
- Battery chargers where output voltage varies during operation
Q & A
- What is the primary function of the NCP1207APG?
The NCP1207APG is a PWM Current-Mode Controller designed for free-running quasi-resonant operation in switch-mode power supplies.
- What is 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 and simplifying transformer design.
- How does the Overvoltage Protection (OVP) work?
The OVP detects overvoltage conditions by sampling the plateau voltage on the demagnetization winding and enters a latched fault condition if an overvoltage is detected.
- What is the purpose of the internal soft-start feature?
The internal soft-start feature ensures a gradual increase in the peak current during startup, preventing high inrush currents and ensuring stable operation.
- What are the key benefits of the quasi-resonant operation mode?
Quasi-resonant operation reduces EMI and video noise perturbations by restarting the MOSFET in the minimum of the drain-source wave.
- How does the controller handle overcurrent conditions?
The controller features auto-recovery overcurrent protection, which reduces the switching frequency and enters burst mode to prevent damage during overcurrent conditions.
- What is the significance of the internal temperature shutdown feature?
The internal temperature shutdown feature protects the device from overheating by shutting down the controller if the junction temperature exceeds a safe limit.
- Can the NCP1207APG be used in high-voltage applications?
Yes, the NCP1207APG is designed for high-voltage applications and can handle maximum voltages up to 500 V on the HV pin.
- Is the NCP1207APG suitable for battery charger applications?
Yes, the NCP1207APG is particularly useful in battery charger applications where the output voltage varies during operation.
- What are the ESD protection ratings for the NCP1207APG?
The NCP1207APG has ESD protection rated at 2000 V per Human Body Model (HBM) and 200 V per Machine Model (MM).
