NCP1250: PWM Controller, Current Mode, for Offline Power Supplies

The NCP1250 is a highly integrated PWM controller capable of delivering a rugged and high performance offline power supply in a tiny TSOP-6 package. With a supply range up to 28 V, the controller hosts a jittered 65 kHz or 100 kHz switching circuitry operated in peak current mode control. When the power on the secondary side starts to decrease, the controller automatically folds back its switching frequency down to a minimum level of 26 kHz. As the power further goes down, the part enters skip cycle while limiting the peak current. 40W AdapterOver Power Protection (OPP) is a difficult exercise especially when no-load standby requirements drive the converter specifications. The ON proprietary integrated OPP lets you harness the maximum delivered power without affecting your standby performance simply via two external resistors. An Over Voltage Protection input is also combined on the same pin and protects the whole circuitry in case of optocoupler failure or adverse open loop operation. Finally, a timer-based short-circuit protection offers the best protection scheme, letting you precisely select the protection trip point irrespective of a loose coupling between the auxiliary and the power windings.

Features
  • Non-dissipative internal and adjustable Over Power Protection (OPP) circuits
  • Frequency Foldback down to 26 kHz and Skip-Cycle in light load conditions
  • Internal Ramp Compensation
  • Frequency jittering from full load to skip-cycle
  • Latch input for OVP and OTP implementations
  • See NCP1251 for integrated Over Voltage Protection (OVP) monitoring on the Vcc pin
Benefits
  • Limits maximum delivered power without affecting standby performance
  • High efficiency in light load conditions
  • Reduces the number of external components
  • Improved EMI performance
  • Simple implementation of required protection functions
Applications
  • Offline Adapters
  • AC-DC converters
End Products
  • Set-top Boxes
  • Printers
  • Notebooks and Netbooks
Design & Development Tools (2)
Document TitleDocument ID/SizeRevisionRevision Date
Flyback Current Mode Loop Compensation Design WorksheetFLYBACK DWS.XLS.ZIP (3516kB)10Dec, 2014
Flyback Transformer Design ToolFLYBACK TRANSFORMER DESIGN TOOL (21.0kB)0
Package Drawings (2)
Document TitleDocument ID/SizeRevision
8 LEAD PDIP626-05 (35.0kB)P
TSOP-6318G-02 (64.1kB)V
Application Notes (7)
Document TitleDocument ID/SizeRevisionRevision Date
A 12V/40W Demonstrator with NCP1250AND8486/D (128.0kB)0
A 60 W ac-dc Demonstrator with NCP1250AND8468/D (490.0kB)2
Adjusting the Over Temperature Protection Trip Point in NCP1250-Based AdaptersAND9057/D (110.0kB)0
Compensating the Negative Voltage Spike on the NCP1250 OPP PinAND9066/D (179.0kB)1
Loop Control Design of an ac-dc Adapter Using the NCP1250AND8453/D (357.0kB)0
The NCP1250, a Versatile Tiny Controller for Offline ConvertersAND8469/D (271kB)3
Tips and Tricks for NCP1250AND8488/D (242.0kB)0
Evaluation Board Documents (4)
Document TitleDocument ID/SizeRevisionRevision Date
NCP1250B40WGEVB Bill of Materials ROHS CompliantNCP1250B40WGEVB_BOM_ROHS.PDF (68kB)1
NCP1250B40WGEVB Gerber Layout Files (Zip Format)NCP1250B40WGEVB_GERBER.ZIP (29.0kB)0
NCP1250B40WGEVB SchematicNCP1250B40WGEVB_SCHEMATIC.PDF (16.0kB)0
NCP1250B40WGEVB Test ProcedureNCP1250B40WGEVB_TEST_PROCEDURE.PDF (286.0kB)0
Simulation Models (3)
Document TitleDocument ID/SizeRevisionRevision Date
ICAPS Flyback Drawing with NCP1250NCP1250_FLYBACK_CIRCUIT (315.0kB)0
NCP1250 & NCP1251 Simplis ModelNCP1250_NCP1251_SIMPLIS_MODEL (416.0kB)1
OrCAD Models for NCP1250NCP1250_ORCAD_MODEL (105.0kB)0
Data Sheets (1)
Document TitleDocument ID/SizeRevisionRevision Date
PWM Controller, Current Mode, for Offline Power SuppliesNCP1250/D (284kB)10Apr, 2015
Evaluation/Development Tool Information
ProductStatusComplianceShort Description
NCP1250B40WGEVBActivePb-free40 W Notebook Adapter Demonstration Evaluation Board
Order Information
ProductStatusCompliancePackageMSL*ContainerBudgetary Price/Unit
NCP1250ASN100T1GActivePb-free Halide freeTSOP-6318G-021Tape and Reel3000$0.14
NCP1250ASN65T1GActivePb-free Halide freeTSOP-6318G-021Tape and Reel3000$0.14
NCP1250BP65GActivePb-free Halide freePDIP-8626-05NATube50$0.2267
NCP1250BSN100T1GActivePb-free Halide freeTSOP-6318G-021Tape and Reel3000$0.14
NCP1250BSN65T1GActivePb-free Halide freeTSOP-6318G-021Tape and Reel3000$0.14
Specifications
ProductTopologyControl Modefsw Typ (kHz)Stand-by ModeUVLO (V)Short Circuit ProtectionLatchSoft StartVCC Max (V)Drive Cap. (mA)
NCP1250ASN100T1GFlybackCurrent Mode100Yes8.8YesYesYes28300 / 500
NCP1250ASN65T1GFlybackCurrent Mode65Yes8.8YesYesYes28300 / 500
NCP1250BP65GFlybackCurrent Mode65Yes8.8YesYesYes28300 / 500
NCP1250BSN100T1GFlybackCurrent Mode100Yes8.8YesYesYes28300 / 500
NCP1250BSN65T1GFlybackCurrent Mode65Yes8.8YesYesYes28300 / 500
PWM Controller, Current Mode, for Offline Power Supplies (284kB) NCP1250
Flyback Current Mode Loop Compensation Design Worksheet NCP1129
Flyback Transformer Design Tool NCP1129
A 12V/40W Demonstrator with NCP1250 NCP1251
A 60 W ac-dc Demonstrator with NCP1250 NCP1251
Adjusting the Over Temperature Protection Trip Point in NCP1250-Based Adapters NCP1250
Compensating the Negative Voltage Spike on the NCP1250 OPP Pin NCP1250
Loop Control Design of an ac-dc Adapter Using the NCP1250 NCP1251
The NCP1250, a Versatile Tiny Controller for Offline Converters NCP1251
Tips and Tricks for NCP1250 NCP1251
NCP1250B40WGEVB BOM ROHS NCP1250B40WGEVB
NCP1250B40WGEVB GERBER NCP1250B40WGEVB
NCP1250B40WGEVB SCHEMATIC NCP1250B40WGEVB
NCP1250B40WGEVB TEST PROCEDURE NCP1250B40WGEVB
ICAPS Flyback Drawing with NCP1250 NCP1251
NCP1250 & NCP1251 Simplis Model NCP1250
OrCAD Models for NCP1250 NCP1251
8 LEAD PDIP NE592
TSOP-6 STF202
NCP1250