NCP1238: Controller, Fixed Frequency, Current Mode, for Flyback Converters
The NCP1238 is a new generation of the NCP12xx fixed-frequency current-mode controllers featuring Dynamic Self-Supply (DSS), pin to pin compatible with the previous generation. The DSS function greatly simplifies the design of the auxiliary supply and the VCC capacitor by activating the internal start-up current source to supply the controller during transients. Due to its proprietary Soft-Skip™ mode combined with frequency foldback, the controller exhibits excellent efficiency in light load condition while still achieving very low standby power consumption. This Soft-Skip feature also dramatically reduces the risk of acoustic noise, which enables the use of inexpensive transformers and capacitors in the clamping network. Internal frequency jittering, ramp compensation, and a versatile latch input make this controller an excellent candidate for converters where ruggedness and components cost are the key constraints. In addition, the controller includes a new high voltage circuitry that combines a startup current source and a brown-out / line OVP detector able to sense the input voltage either from the rectified ac line or the dc filtered bulk voltage. Finally, due to a careful design, the precision of critical parameters is well controlled over the entire temperature range (-40°C to +125°C), enabling easier design and increased safety (e.g. ±5% for the peak current limit, ±7% for the oscillator).
特性- Timer-Based Overload Protection with AutoRecovery (Option B) or Latched (Option A) Operation
- Frequency Jittering
- Frequency Foldback transitioning into Soft-Skip
- High-Voltage Current Source with DSS with Built-in Brown-out and Line Overvoltage Protections
- Fixed-Frequency Current-Mode Operation with Built-in Ramp Compensation
- Adjustable Overpower Compensation
- Latch-off Input for Severe Fault Conditions, with Direct Connection of an NTC for Overtemperature Protection (OTP)
- Protection Against Winding Short-Circuit
- 65 kHz Oscillator (100 kHz and 133 kHz Versions Available Upon Request)
- VCC Operation up to 28 V
- Increased Precision on Critical Parameters
- 1.0 A Peak Current Drive Capability
- 4.0 ms Soft-Start
- Internal Thermal Shutdown with Hysteresis
- These Devices are Pb-Free, Halogen free/BFR free and are ROHS compliant
| 优势- Overload protection independent of the auxiliary voltage
- Reduced EMI Signature
- Improved Performance in Standby
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应用- Ac-dc Adapters for Notebooks, LCD, and Printers
- Offline Battery Chargers
- Consumer Electronic Power Supplies
- Auxiliary/Housekeeping Power Supplies
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封装
设计和开发工具 (1)
数据表 (1)
应用注释 (2)
封装图纸 (1)
产品订购型号
| 产品 | 状况 | Compliance | 封装 | MSL* | 容器 | 预算价格 (1千个数量的单价） |
|---|
| NCP1238AD65R2G | Active | Pb-free
Halide free | SOIC-7 | 751U | 1 | Tape and Reel | 2500 | $0.6667 |
| NCP1238BD65R2G | Active | Pb-free
Halide free | SOIC-7 | 751U | 1 | Tape and Reel | 2500 | $0.6667 |
订购产品技术参数
| Product | Topology | Control Mode | fsw Typ (kHz) | Stand-by Mode | UVLO (V) | Short Circuit Protection | Latch | Soft Start | VCC Max (V) | Drive Cap. (mA) |
|---|
| NCP1238AD65R2G | Flyback | Current Mode | 65 | Yes | 9.5 | Yes | Yes | Yes | 28 | 1000 / 1000 |
| NCP1238BD65R2G | Flyback | Current Mode | 65 | Yes | 9.5 | Yes | Yes | Yes | 28 | 1000 / 1000 |
