NCP1236B65NBGEVB: 65 W Notebook Adapter Demonstration Evaluation Board

The NCP1236 is a new fixed frequency current mode controller with dynamic self-supply (DSS) function. The device is pin-compatible with the previous NCP12xx series. The DSS function greatly simplifies the design of auxiliary power supplies and VCC capacitors by activating an internal startup current source to power the controller during transients. Due to frequency foldback, the controller exhibits extremely high efficiency under light load conditions while still achieving very low standby power consumption. Internal frequency jittering, slope compensation and a versatile latch input make this controller an excellent choice for converters where component cost is a key constraint. In addition, the controller includes a new high-voltage circuit that combines a startup current source and a voltage undervoltage detector, capable of detecting the input voltage from a rectified AC line or a DC filtered large voltage. The high-voltage detection circuit is also used for over-power protection purposes. Over-power protection, overload protection and subsequent protection functions increase the safety level of the final application. Finally, due to careful design, the accuracy of key parameters is well controlled over the entire temperature range (-40 degrees Celsius to +125 degrees Celsius). Features and Applications FeaturesFixed-frequency current-mode operation with built-in slope compensation65 kHz or 100 kHz oscillator frequencyFrequency foldback followed by skip mode for maximum performance in light load and standby conditionsVCC operation up to 28 V with overvoltage detection4.0 ms soft-startFrequency modulation for softening EMI signature, including in frequency foldback modeThe

NCP1236 is a new fixed-frequency current-mode controller featuring Dynamic Self-Supply (DSS). This device is pin-to-pin compatible with the previous NCP12xx families. The DSS function greatly simplifies the design of the auxiliary supply and the VCC capacitor by activating the internal startup current source to supply the controller during transients. Due to frequency foldback, the controller exhibits excellent efficiency in light load condition while still achieving very low standby power consumption. Internal frequency jittering, ramp compensation, and a versatile latch input make this controller an excellent candidate for converters where components cost is the key constraints.In addition, the controller includes a new high voltage circuitry that combines a start-up current source and a brown-out detector able to sense the input voltage either from the rectified ac line or the dc filtered bulk voltage. The high voltage sensing circuitry is used for the overpower protection purposes as well. Overpower protection, overload protection, and next protective features increase the safety level of the final application.Finally, due to a careful design, the precision of critical parameters is well controlled over the entire temperature range (-40 degrees Celsius to +125 degrees Celsius).
Features and Applications


Features
Fixed-Frequency Current- Mode Operation with Built-In Ramp Compensation
65 kHz or 100 kHz Oscillator Frequency
Frequency Foldback then Skip Mode for Maximized Performance in Light Load and Standby Conditions
VCC Operation up to 28 V, with Overvoltage Detection
4.0 ms Soft-Start
Frequency Modulation for Softened EMI Signature, including during Frequency Foldback mode