NCP1238
Controller, Fixed Frequency, Current Mode, for Flyback Converters
制造商：ON
产品信息
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 V
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).
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).
- 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 DSSwith 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)
- V
- 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
电路图、引脚图和封装图
NCP1238电路图