NCP1234AD65R2G Description
The NCP1234 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 dramatically 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 conditions while still achieving deficient 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 constraint. It features a timer?based fault detection that ensures the detection of overload independently of an auxiliary winding, and an adjustable compensation to help keep the maximum power independent of the
input 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).
NCP1234AD65R2G Features
Fixed?Frequency Current?Mode Operation with Built?In Ramp
Compensation
65 kHz or 100 kHz Oscillator Frequency version
Frequency Foldback then Skip Mode for Maximized Performance in
Light Load and Standby Conditions
Timer?Based Overload Protection with Latched (option A) or
Auto?Recovery (option B) Operation
High?voltage Current Source with Dynamic Self?Supply,
Simplifying the Design 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, Allowing Direct
Connection of an NTC for Overtemperature Protection (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 NCP12xx
Series
These Devices are Pb?Free, Halogen Free/BFR Free
and are RoHS Compliant
NCP1234AD65R2G Applications
AC?DC Adapters for Notebooks, LCD, and Printers
Offline Battery Chargers
Consumer Electronic Power Supplies
Auxiliary/Housekeeping Power Supplies
