Overview
The NCP1252DDR2G, produced by onsemi, is a high-performance current-mode PWM controller designed for building cost-effective and reliable ac-dc switching supplies, particularly for ATX power supplies and adapter applications. This controller integrates various features to ensure robust and efficient power supply operation, including peak current-mode control, adjustable switching frequency, and comprehensive protection mechanisms.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| VCC Startup Threshold | 9.4 | 10 | 10.6 | V |
| VCC Minimum Operating Voltage | 8.4 | 9 | 9.6 | V |
| VCC Hysteresis | 0.9 | 1.0 | 1.0 | V |
| Switching Frequency | 92 | 100 | 108 | kHz |
| Maximum Switching Frequency | - | - | 500 | kHz |
| Maximum Duty Cycle (A Version) | 45.6 | 48 | 49.6 | % |
| Maximum Duty Cycle (B Version) | 76 | 80 | 84 | % |
| Maximum Duty Cycle (C Version) | 61 | 65 | 69 | % |
| Maximum Duty Cycle (D & E Versions) | 44.2 | 45.6 | 47.2 | % |
| Drive Output Source/Sink Capability | +500 mA / -800 mA | - | - | mA |
| Package Type | - | - | SOIC-8, PDIP-8 | - |
Key Features
- Peak Current Mode Control: Implements peak current-mode control topology, similar to UC384X-like features, for robust power supply design.
- Adjustable Switching Frequency: The switching frequency can be adjusted up to 500 kHz using a resistor connected to ground.
- Frequency Jittering: Frequency jittering of ±5% of the switching frequency to soften the EMI signature.
- Latched Primary Over Current Protection: With a fixed delay of 10 ms (extended to 150 ms in E version) for detecting output overload.
- Delayed Operation Upon Start-up: Internal fixed timer for delayed operation upon start-up in A, B, and C versions.
- Adjustable Soft-start Timer: Adjustable soft-start timer to control the peak current sensed during start-up.
- Brown-Out Detection: Auto-recovery brown-out detection to protect against low input voltage conditions.
- Internal Ramp Compensation: Adjustable internal ramp compensation to stabilize the switching operation.
- No Load Regulation: Ready for updated no load regulation specifications to ensure efficient operation under no-load conditions.
Applications
- Power Supplies for PC Silver Boxes: Ideal for ATX power supplies and other PC power supply applications.
- Games Adapters: Suitable for power supplies in gaming adapters and other high-power consumer electronics.
- Flyback and Forward Converters: Can be used in both flyback and forward converter topologies.
Q & A
- What is the primary function of the NCP1252DDR2G?
The NCP1252DDR2G is a current-mode PWM controller designed for building cost-effective and reliable ac-dc switching supplies, particularly for ATX power supplies and adapter applications.
- What is the adjustable switching frequency range of the NCP1252DDR2G?
The switching frequency can be adjusted up to 500 kHz using a resistor connected to ground.
- What protection mechanisms does the NCP1252DDR2G offer?
The controller offers latched primary over current protection, brown-out detection, and short circuit or overload protection.
- What is the maximum duty cycle for different versions of the NCP1252DDR2G?
The maximum duty cycle varies by version: 50% for A version, 80% for B version, 65% for C version, and 47.5% for D & E versions.
- How does the NCP1252DDR2G handle no-load conditions?
The controller is designed to handle no-load conditions efficiently, ensuring the converter runs at the minimum duty cycle fixed by the propagation delay and driving blocks, and can impose a zero duty cycle if necessary.
- What is the purpose of the internal ramp compensation in the NCP1252DDR2G?
The internal ramp compensation helps stabilize the switching operation by compensating for the slope of the current sense signal.
- What are the typical applications of the NCP1252DDR2G?
The NCP1252DDR2G is typically used in power supplies for PC silver boxes, games adapters, and both flyback and forward converter topologies.
- What is the package type of the NCP1252DDR2G?
The NCP1252DDR2G is available in SOIC-8 and PDIP-8 packages.
- Does the NCP1252DDR2G support synchronization capability?
No, the NCP1252DDR2G does not have synchronization capability.
- How does the brown-out protection work in the NCP1252DDR2G?
The brown-out protection monitors the input voltage through the BO pin and stops pulsing if the input level falls below the VBO level, resuming operation via a new soft start sequence when the input level returns to normal.
