NCP1207B: PWM Controller, Free Running Quasi-Resonant Current Mode

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 micro 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 micro 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
  • Auto-Recovery Over Current Protection
  • 500 mA Peak Current Source/Sink Capability
  • Internal 1.0 ms SoftStart
  • Internal 4.5 s Minimum TOFF
  • Latched Over Voltage Protection
Applications
  • Auxiliary power supplies
End Products
  • AC/DC adapters for notebook
  • Offline battery chargers
Design & Development Tools (2)
Document TitleDocument ID/SizeRevisionRevision Date
Worksheet, QR Power Supply, BasicQR BASIC DWS.XLS (53.0kB)2
Worksheet, QR Power Supply, ComplexQR COMPLEX DWS.XLS (82.0kB)2
Data Sheets (1)
Document TitleDocument ID/SizeRevisionRevision Date
PWM Controller, Free Running Quasi-Resonant Current ModeNCP1207B/D (395.0kB)11
Application Notes (9)
Document TitleDocument ID/SizeRevisionRevision Date
A 30 W Power Supply Operating in A Quasi-Square Wave Resonant ModeAND8129/D (246.0kB)0
A 75 W TV Power Supply Operating in Quasi-square Wave Resonant Mode Using NCP1207 ControllerAND8145/D (326.0kB)0
A Quasi-Resonant SPICE Model Eases Feedback Loop DesignsAND8112/D (205.0kB)1
Determining the Free-Running Frequency for QR SystemsAND8089/D (66.0kB)0
High Efficiency 8 Output, 60 W Set Top Box Power Supply DesignAND8252/D (99.0kB)0
Implementing NCP1207 in QR 24 W AC-DC Converter with Synchronous RectifierAND8127/D (129.0kB)1
Stability Analysis in Multiple Loop SystemsAND8327/D (213.0kB)0
Synchronizing NCP1207 (NCP1377/B, NCP1378)AND8187/D (46.0kB)0
Tips and Tricks to Build Efficient Circuits with NCP1200AND8069/D (139.0kB)1
Package Drawings (1)
Document TitleDocument ID/SizeRevision
SOIC 7 CASE OUTLINE751U (62.0kB)E
Simulation Models (4)
Document TitleDocument ID/SizeRevisionRevision Date
Large signal model for AC analysis (IsSPICE)NCP1207ACIS (235.0kB)0
Large signal model for AC analysis (PSPICE)NCP1207ACPS (38.0kB)0
Simplified freerun model for fast QR simulation (IsSPICE)NCP1207IS (31.0kB)0
Simplified freerun model for fast QR simulation (PSPICE)NCP1207PS (18.0kB)0
Order Information
ProductStatusCompliancePackageMSL*ContainerBudgetary Price/Unit
NCP1207BDR2GActivePb-free Halide freeSOIC-7751U1Tape and Reel2500$0.35
Specifications
ProductTopologyControl Modefsw Typ (kHz)Stand-by ModeUVLO (V)Short Circuit ProtectionLatchSoft StartVCC Max (V)Drive Cap. (mA)
NCP1207BDR2GFlybackCurrent ModeUp to 1000YesYesYesYesYes18500 / 500
PWM Controller, Free Running Quasi-Resonant Current Mode (395.0kB) NCP1207B
Worksheet, QR Power Supply, Basic NCP1377
Worksheet, QR Power Supply, Complex NCP1377
A 30 W Power Supply Operating in A Quasi-Square Wave Resonant Mode NCP1308
A 75 W TV Power Supply Operating in Quasi-square Wave Resonant Mode Using NCP1207 Controller NCP1308
A Quasi-Resonant SPICE Model Eases Feedback Loop Designs NCP1377
Determining the Free-Running Frequency for QR Systems NCP1377
High Efficiency 8 Output, 60 W Set Top Box Power Supply Design NCP1207B
Implementing NCP1207 in QR 24 W AC-DC Converter with Synchronous Rectifier NCP1308
Stability Analysis in Multiple Loop Systems NCP1055
Synchronizing NCP1207 (NCP1377/B, NCP1378) NCP1377
Tips and Tricks to Build Efficient Circuits with NCP1200 NCP1308
Large signal model for AC analysis (IsSPICE) NCP1377
Large signal model for AC analysis (PSPICE) NCP1377
Simplified freerun model for fast QR simulation (IsSPICE) NCP1377
Simplified freerun model for fast QR simulation (PSPICE) NCP1377
SOIC 7 CASE OUTLINE NCL30060
NCP1207B