Overview
The NCP1252APG, produced by onsemi, is a current-mode PWM controller designed for building cost-effective and reliable AC-DC switching supplies, particularly for ATX power supplies and adapter markets. This controller integrates several key features to ensure robust and efficient power supply operation.
Key Specifications
| Characteristic | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Startup threshold at VCC increasing (A, B, C versions) | 9.4 | 13.1 | 10.6 | V |
| Minimum Operating voltage at VCC decreasing (A, B, C versions) | 8.4 | 9 | 9.6 | V |
| Hysteresis between VCC(on) and VCC(min) (A, B, C versions) | 0.9 | 1.0 | 4.5 | V |
| Output voltage rise-time (VCC = 15 V, CDRV = 1 nF) | - | 26 | - | ns |
| Output voltage fall-time (VCC = 15 V, CDRV = 1 nF) | - | 22 | - | ns |
| Clamping voltage (maximum gate voltage) (VCC = 25 V) | - | 15 | 18 | V |
| Switching Frequency Range | 50 kHz | - | 500 kHz | - |
Key Features
- Peak Current Mode Control: Implements peak current-mode control topology, similar to UC384X, for building rugged power supplies.
- Adjustable Switching Frequency: The switching frequency can be set between 50 kHz and 500 kHz using a resistor connected to ground.
- Frequency Jittering: The frequency jittering feature softens the EMI signature by spreading out peak energy within a band ±5% from the center frequency.
- Latched Primary Over Current Protection: Offers latched primary over current protection with a 10 ms fixed delay, extendable to 150 ms in E version.
- Delayed Operation Upon Start-up: Features an internal fixed timer for delayed operation upon start-up (A, B, and C versions only).
- Adjustable Soft-start Timer: Allows for adjustable soft-start duration using a capacitor connected to the soft-start pin.
- Brown-Out Detection: Includes auto-recovery Brown-Out detection to protect against low input voltages.
- Gate Drive Clamping: Prevents the gate voltage from exceeding 15 V to protect power MOSFETs.
- Low Startup-Current: Ensures low no-load standby current.
Applications
The NCP1252APG is specifically designed for use in ATX power supplies and adapter markets. It is suitable for building cost-effective and reliable AC-DC switching supplies. The controller's features make it an ideal choice for applications requiring robust and efficient power supply operation.
Q & A
- What is the primary function of the NCP1252APG?
The NCP1252APG is a current-mode PWM controller designed for building AC-DC switching supplies, particularly for ATX power supplies and adapter markets.
- What is the range of the adjustable switching frequency?
The switching frequency can be adjusted between 50 kHz and 500 kHz.
- What is the purpose of the frequency jittering feature?
The frequency jittering feature softens the EMI signature by spreading out peak energy within a band ±5% from the center frequency.
- How does the Brown-Out detection work?
The controller includes auto-recovery Brown-Out detection to protect against low input voltages.
- What is the maximum gate voltage clamping level?
The gate voltage is clamped to prevent it from exceeding 15 V.
- How is the soft-start duration adjusted?
The soft-start duration is adjusted using a capacitor connected to the soft-start pin.
- What is the significance of the internal fixed timer?
The internal fixed timer delays the operation upon start-up (A, B, and C versions only).
- What type of protection does the controller offer against overcurrent?
The controller offers latched primary over current protection with a 10 ms fixed delay, extendable to 150 ms in E version.
- What is the typical operating voltage range for VCC?
The VCC can operate up to 28 V continuously and accepts transient voltage up to 30 V during 10 ms.
- What package type is the NCP1252APG available in?
The NCP1252APG is available in a SOIC-8 package.
