Overview
The NCP1217AD100R2G, produced by onsemi, is an advanced PWM controller designed for fixed-frequency, current-mode operation. This component is an enhanced version of the NCP1203-based controllers and is housed in an SO-8 or PDIP-7 package. It is particularly suited for applications requiring low part-count, such as low-cost AC/DC adapters and TV power supplies. The NCP1217 features high drive capability, internal ramp compensation, and built-in overvoltage protection, making it an ideal alternative to UC384X-based designs.
Key Specifications
| Characteristic | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Oscillation Frequency (65 kHz Version) | 58.5 | 65 | 71.5 | kHz |
| Oscillation Frequency (100 kHz Version) | 90 | 100 | 110 | kHz |
| Oscillation Frequency (133 kHz Version) | 120 | 133 | 146 | kHz |
| Maximum Duty-Cycle (NCP1217) | 69 | 74 | 80 | % |
| Maximum Duty-Cycle (NCP1217A) | 42 | 46.5 | 50 | % |
| Maximum Junction Temperature | 150 | °C | ||
| Storage Temperature Range | -60 | 150 | °C | |
| ESD Capability (HBM Model) | 2.0 kV | |||
| ESD Capability (Machine Model) | 200 V |
Key Features
- Current-Mode with Adjustable Skip-Cycle Capability: The NCP1217 operates in current-mode and features an adjustable skip-cycle mode to enhance efficiency at light loads.
- Built-in Internal Ramp Compensation: This feature prevents subharmonic oscillations in continuous conduction mode designs.
- Auto-Recovery Internal Output Short-Circuit Protection: The device enters a safe burst mode during overcurrent conditions and auto-recovers once the fault is cleared.
- Internal 1.0 ms Soft-Start (NCP1217A Only): Ensures a smooth startup sequence.
- High-Voltage Startup FET: Provides a clean and lossless startup sequence by injecting a constant current into the VCC capacitor.
- Externally Triggerable Latchoff: Allows for external signals to permanently disable the output pulses.
- Low No-Load Standby Power: The device skips unwanted switching cycles at low power levels to reduce standby power consumption.
Applications
The NCP1217 is widely used in various applications, including:
- Low-Cost AC/DC Adapters: Ideal for applications requiring low part-count and high efficiency.
- TV Power Supplies: Enhances performance and reduces component count in TV power supply designs.
- VCRs and Other Consumer Electronics: Helps in achieving low no-load standby power and reducing switching losses at low power levels.
Q & A
- What is the primary function of the NCP1217?
The NCP1217 is a PWM controller designed for fixed-frequency, current-mode operation, primarily used in AC/DC adapters and other power supply applications.
- What are the key features of the NCP1217?
The key features include current-mode operation with adjustable skip-cycle capability, built-in internal ramp compensation, auto-recovery internal output short-circuit protection, and high-voltage startup FET.
- How does the NCP1217 handle overcurrent conditions?
The device enters a safe burst mode during overcurrent conditions and auto-recovers once the fault is cleared.
- What is the purpose of the skip-cycle mode in the NCP1217?
The skip-cycle mode enhances efficiency at light loads by skipping unwanted switching cycles, reducing standby power consumption.
- How does the NCP1217 ensure a clean startup sequence?
The high-voltage startup FET injects a constant current into the VCC capacitor, ensuring a clean and lossless startup sequence.
- What is the significance of internal ramp compensation in the NCP1217?
Internal ramp compensation prevents subharmonic oscillations in continuous conduction mode designs.
- Can the NCP1217 be externally triggered to latch off?
Yes, the device allows for external signals to permanently disable the output pulses by pulling the Adj pin above 3.1 V.
- What are the typical applications of the NCP1217?
The NCP1217 is typically used in low-cost AC/DC adapters, TV power supplies, and other consumer electronics requiring low no-load standby power.
- What are the ESD protection ratings for the NCP1217?
The device has ESD protection rated at 2.0 kV for the Human Body Model (HBM) and 200 V for the Machine Model.
- What is the maximum junction temperature for the NCP1217?
The maximum junction temperature is 150°C.
