OnSemiNPC133760W Adapter Reference Design Solution

OnSemi's NCP1337 is a chip that combines a current mode regulator and a demagnetization detector to fully ensure borderline/critical conduction mode under any load/transmission line conditions together with minimum leakage voltage switching (quasi-resonant operation). Because of the Soxyless concept, the transformer core reset detection is done internally without using any external signal. According to the CISPR-22 EMI limit standard, the internal frequency is limited to 130kHz, preventing the controller from operating at 150kHz. The chip has an overload protection restart function. Once overloaded, the device will automatically restart and recover. This article mainly introduces the NCP1337 chip, chip characteristics, application direction and internal structure diagram. This article also introduces a 60W reference design solution using the NCP1337 chip as the main chip, and gives an introduction to the solution, the solution schematic, the PCB board drawing and the list of components.

The NCP1337 combines a true current mode modulator and a demagnetization detector which ensures full Borderline/Critical Conduction Mode in any load/line conditions together with minimum drain voltage switching (Quasi−Resonant operation). The transformer core reset detection is done internally, without using any external signal, due to the Soxyless concept. The frequency is internally limited to 130 kHz, preventing the controller to operate above the 150 kHz CISPR−22 EMI starting limit.

feedback pin activity, the controller enters skip mode as soon as the power demand falls below a predetermined level. As each restart is softened by an internal Soft−Skip_, and as the frequency cannot go below 25 kHz, no audible noise can be heard.

The NCP1337 also features an efficient protective circuitry which, in presence of an overcurrent condition, disables the output pulses and enters a safe burst mode, trying to restart. Once the default has gone, the device auto−recovers. Also included is a bulk voltage monitoring function (known as brown−out protection), an adjustable overpower compensation, and a VCC OVP. The controller immediately restarts after any of these conditions, unless the fault timer has timed out. Finally, an internal 4.0 ms soft−start eliminates the traditional startup stress.

NCP1337 Key Features:

• Free−Running Borderline/Critical Mode Quasi−Resonant Operation
• Current−Mode
• Soft−Skip Mode with Minimum Switching Frequency for Standby
• Auto−Recovery Short −Circuit Protection Independent of Auxiliary Voltage
• Overvoltage Protection
• Brown-Out Protection
• Two Externally Triggerable Fault Comparators (one for a disable function, and the other for a permanent latch)
• Internal 4.0 ms Soft−Start
• 500 mA Peak Current Drive Sink Capability
• 130 kHz Max Frequency
• Internal Leading Edge Blanking
• Internal Temperature Shutdown
• Direct Optocoupler Connection
• Dynamic Self-Supply with Levels of 12 V (On) and 10 V (Off)
• SPICE Models Available for TRANsient and AC Analysis
• These are Pb−Free Devices*
  
 NCP1337 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.)
 

Figure 1. NCP1337 internal block diagramNCP1337ADAPGEVB

solution introduction:

This design using NCP1337 offers a perfect solution for portable DVD, LCD TV, or monitor and notebook adapter applications. This adapter provides effective protection functions such as over-load protection, over-voltage protection, shortcircuit protection and brown-out protection. Thanks to the quasi-resonant operation and synchronous rectifier, this adapter has high efficiency and improved EMI performance. The standby consumption is lower because of the cycle skipping and soft ripple mode.

NCP1337ADAPGEVB solution schematic:

Figure 2. NCP1337ADAPGEVB solution schematicNCP1562-100WGEVB

solution material list:



PCB component layout: