onsemi NCP1217AD100R2G

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.

• 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.

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.

1. 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.

2. 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.

3. 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.

4. 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.

5. 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.

6. What is the significance of internal ramp compensation in the NCP1217?

   Internal ramp compensation prevents subharmonic oscillations in continuous conduction mode designs.

7. 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.

8. 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.

9. 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.

10. What is the maximum junction temperature for the NCP1217?

    The maximum junction temperature is 150°C.