NCP1234 Series

Controller, Fixed Frequency, Current Mode, for Flyback Converters

Catalog

Controller, Fixed Frequency, Current Mode, for Flyback Converters

Part	Fault Protection	Frequency - Switching	Output Isolation	Operating Temperature [Max]	Operating Temperature [Min]	Voltage - Supply (Vcc/Vdd) [Min]	Voltage - Supply (Vcc/Vdd) [Max]	Duty Cycle	Internal Switch(s)	Mounting Type	Package / Case [custom]	Package / Case	Package / Case [custom]	Package / Case	Supplier Device Package	Topology	Voltage - Start Up
ON Semiconductor NCP1234BD65R2G	Current Limiting Over Load Over Temperature	65 kHz	Isolated	150 °C	-40 °C	9.5 V	28 V	80 %		Surface Mount	7	8-SOIC	3.9 mm	0.154 in	7-SOIC	Flyback	12 V

Catalog

Controller, Fixed Frequency, Current Mode, for Flyback Converters

Key Features

• Frequency Foldback then Skip Mode in light load and standby conditions

• High voltage current source with brown-out detection and dynamic self-supply

• Frequency Jittering

• 4.0 ms Soft-Start

• Adjustable Overpower Compensation

• Latched / Autorecovery Timer-Based Overload Protection

Description

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 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.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.