The NCP1207A/B combines a true current mode modulator and a

demagnetization detector to ensure full borderline/critical Conduction

Mode in any load/line conditions and minimum drain voltage switching

(Quasi−Resonant operation). Due to its inherent skip cycle capability,

the controller enters burst mode as soon as the power demand falls

below a predetermined level. As this happens at low peak current, no

audible noise can be heard. For the NCP1207A, an internal 8.0 s timer

prevents the free−run frequency to exceed 125 kHz (therefore below the

150 kHz CISPR−22 EMI starting limit), while the skip adjustment

capability lets the user select the frequency at which the burst foldback

takes place. For the NCP1207B, the internal timer duration is reduced to

4.5 s to allow operation at higher frequencies (up to 200 kHz).

The Dynamic Self−Supply (DSS) drastically simplifies the

transformer design in avoiding the use of an auxiliary winding to

supply the NCP1207A/B. This feature is particularly useful in

applications where the output voltage varies during operation (e.g.

battery chargers). Due to its high−voltage technology, the IC is

directly connected to the high−voltage DC rail. As a result, the

short−circuit trip point is not dependent upon any VCC auxiliary level.

The transformer core reset detection is done through an auxiliary

winding which, brought via a dedicated pin, also enables fast

Overvoltage Protection (OVP). Once an OVP has been detected, the

IC permanently latches off.

Finally, the continuous feedback signal monitoring implemented

with an overcurrent fault protection circuitry (OCP) makes the final

design rugged and reliable.

Features

• Free−Running Borderline/Critical Mode Quasi−Resonant Operation

• Current−Mode with Adjustable Skip−Cycle Capability

• No Auxiliary Winding VCC Operation

• Auto−Recovery Overcurrent Protection

• Latching Overvoltage Protection

• External Latch Triggering, e.g. Via Overtemperature Signal

• 500 mA Peak Current Source/Sink Capability

• Undervoltage Lockout for VCC Below 10 V

• Internal 1.0 ms Soft−Start

• Internal 8.0 s Minimum TOFF for NCP1207A,

4.5 s Minimum TOFF for NCP1207B

• Adjustable Skip Level

• Internal Temperature Shutdown

• Direct Optocoupler Connection

• SPICE Models Available for TRANsient Analysis

• These are Pb−Free and Halide−Free Devices

Typical Applications

• AC−DC Adapters for Notebooks, etc.

• Offline Battery Chargers

• Consumer Electronics

(DVD Players, Set−Top Boxes, TVs, etc.)

• Auxiliary Power Supplies

(USB, Appliances, TVs, etc.)

NCP1207BDR2G属于集成电路（IC） > AC DC 转换器，离线开关。安森美半导体公司制造生产的NCP1207BDR2GAC DC 转换器，离线开关该系列是元器件级控制产品，用于构建将交流市电转换为直流电（通常电压大幅降低）的设备。集成和未集成系统主要开关元件的器件均包括在内。由于高输入输出电压比，以及此类系统中通常需要隔离，这些器件通常与外部变压器配合使用。尽管通常使用定制变压器来实现此用途，但也有许多专门用于此用途的库存产品，请参见“开关转换器，SMPS 变压器”标题。