Overview
The NCP1252EDR2G is a current-mode PWM controller designed by onsemi, specifically tailored 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, including peak current mode control, adjustable switching frequency, and various protection mechanisms.
Key Specifications
| Characteristics | Symbol | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| Startup threshold at which driving pulses are authorized (VCC increasing) | VCC(on) | 9.4 (A, B, C versions), 13.1 (D & E versions) | 10 (A, B, C versions), 14 (D & E versions) | 10.6 (A, B, C versions), 14.9 (D & E versions) | V |
| Minimum Operating voltage at which driving pulses are stopped (VCC decreasing) | VCC(off) | 8.4 | 9 | 9.6 | V |
| Hysteresis between VCC(on) and VCC(min) | VCC(HYS) | 0.9 (A, B and C versions), 4.5 (D & E versions) | 1.0 (A, B and C versions), 5.0 (D & E versions) | - | - |
| Current Sense Voltage Threshold | VILIM | 0.92 | 1 | 1.08 | V |
| Leading Edge Blanking Duration | tLEB | - | 160 | - | ns |
| Output voltage rise-time | tr | - | 26 | - | ns |
| Output voltage fall-time | tf | - | 22 | - | ns |
| Clamping voltage (maximum gate voltage) | VCL | - | 15 | 18 | V |
Key Features
- Peak Current Mode Control: Implements peak current-mode control topology, similar to UC384X, to build rugged power supplies.
- Adjustable Switching Frequency: The switching frequency can be adjusted up to 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 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 during start-up (A, B, and C versions only).
- Adjustable Soft-start Timer: Allows for adjustable soft-start duration using a capacitor connected to ground.
- 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 MOSFETs.
- Low Startup Current: Ensures low no-load standby current.
- SOIC-8 Package: Saves PCB space and is suitable for cost-sensitive projects.
Applications
The NCP1252EDR2G is specifically designed for use in ATX power supplies and adapter markets. It is ideal for building cost-effective and reliable ac-dc switching supplies. The controller's features make it suitable for a variety of applications requiring robust and efficient power supply solutions.
Q & A
- What is the primary function of the NCP1252EDR2G controller?
The NCP1252EDR2G is a current-mode PWM controller designed to build cost-effective and reliable ac-dc switching supplies, particularly for ATX power supplies and adapter markets.
- How is the switching frequency adjusted in the NCP1252EDR2G?
The switching frequency can be adjusted up to 500 kHz using a resistor connected to ground.
- What is the purpose of the Brown-Out input in the NCP1252EDR2G?
The Brown-Out input monitors the input voltage to offer protection against low input voltages and improves converter safety.
- What is the maximum gate voltage clamping in the NCP1252EDR2G?
The controller includes a low-loss clamping voltage that prevents the gate voltage from exceeding 15 V.
- How does the NCP1252EDR2G handle overcurrent protection?
The controller features latched primary overcurrent protection with a 10 ms fixed delay, extendable to 150 ms in E version.
- What is the significance of the internal fixed timer in the NCP1252EDR2G?
The internal fixed timer allows for delayed operation upon start-up, which is available in A, B, and C versions only.
- How is the soft-start duration adjusted in the NCP1252EDR2G?
The soft-start duration can be adjusted using a capacitor connected to ground.
- What is the typical operating voltage range for the VCC pin of the NCP1252EDR2G?
The VCC pin accepts a voltage range from 8 V up to 28 V.
- What package type does the NCP1252EDR2G come in?
The controller is available in a SOIC-8 package, which saves PCB space and is suitable for cost-sensitive projects.
- What are some key electrical characteristics of the NCP1252EDR2G?
