Onsemi NCP1236

Description

The NCP1236 is a new fixed−frequency current−mode controllerfeaturing Dynamic Self−Supply (DSS). This device is pin−to−pincompatible with the previous NCP12xx families.The DSS function greatly simplifies the design of the auxiliarysupply and the VCC capacitor by activating the internal startup currentsource to supply the controller during transients.Due to frequency foldback, the controller exhibits excellentefficiency in light load condition while still achieving very lowstandby power consumption. Internal frequency jittering, rampcompensation, and a versatile latch input make this controller anexcellent candidate for converters where components cost is the keyconstraints.In addition, the controller includes a new high voltage circuitry thatcombines a start−up current source and a brown−out detector able tosense the input voltage either from the rectified ac line or the dcfiltered bulk voltage. The high voltage sensing circuitry is used for theoverpower protection purposes as well. Overpower protection,overload protection, and next protective features increases safety levelof the final application.Finally, due to a careful design, the precision of critical parametersis well controlled over the entire temperature range (−40°C to+125°C).

Features

Fixed−Frequency Current−Mode Operation with Built−In RampCompensation

• 65 kHz or 100 kHz Oscillator Frequency
• Frequency Foldback then Skip Mode for Maximized Performance inLight Load and Standby Conditions
• Timer−Based Overload Protection with Latched (option A) orAuto−Recovery (option B) Operation, Shortened Overload Timer forIncreased Safety (options C and D), (see all options on page 2)
• High−voltage Current Source with Brown−Outdetection and Dynamic Self−Supply, Simplifying theDesign of the VCC Capacitor
• Frequency Modulation for Softened EMI Signature,including during Frequency Foldback mode
• Adjustable Overpower Compensation
• Latch−off Input for Severe Fault Conditions, AllowingDirect Connection of an NTC for OvertemperatureProtection (OTP)
• VCC Operation up to 28 V, with Overvoltage Detection
• 500 mA Peak Source / Sink Current Drive Capability
• 4.0 ms Soft−Start
• Internal Thermal Shutdown
• Pin−to−Pin Compatible with the Existing NCP12xxSeries
• These Devices are Pb−Free, Halogen Free/BFR Freeand are RoHS Compliant

Typical applications

• Auxiliary/Housekeeping Power Supplies
• Consumer Electronic Power Supplies
• Offline Battery Chargers
• AC−DC Adapters for Notebooks, LCD, and Printers

More information

• Datasheet
• IC product information