The NCP1235 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 component cost is the key constraint.
In addition, the controller includes a new high voltage circuitry that combines a startup 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 other protective features increase the safety and reliability of the final application.
|
Features |
|
Benefits |
| |
| |
| |
|
-
Frequency Foldback then Skip Mode in light load and standby conditions
|
|
-
High efficiency in light and no load conditions
|
-
High voltage current source with brown-out detection and dynamic self-supply
|
|
-
Directly powered from the high voltage rail with integrated brown-out sensing to detect low input voltage.
|
|
|
|
-
Helps pass EMI requirements by spreading out the energy content of frequency peaks
|
|
|
|
-
Minimizes the stress on power components
|
-
Adjustable Overpower Compensation
|
|
-
Monitors the input voltage to limit the amount of power being delivered by the converter
|
-
Latched Timer-Based Overload Protection
|
|
-
Protects against overcurrent
|
|
Applications |
|
End Products |
- AC-DC Adapters
- Consumer Electronics Power Supplies
- Auxiliary/Housekeeping power supplies
|
|
- Notebooks
- LCD TVs
- Printers
|
