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UC3845 Status: ACTIVE

Current-Mode PWM Controller


      
         
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Datasheet

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 UC1845 UC2845 UC3845
TopologyBoost, Flyback, Forward  Boost, Flyback, Forward  Boost, Buck, Flyback, Forward  
Control MethodCurrent Mode  Current Mode  Current Mode  
Duty Cycle(Max)(%)50  50  50  
PWM Outputs(#)1  1  1  
Frequency(Max)(kHz)450  450  450  
UVLO Thresholds On/Off(V)8.4/7.6  8.4/7.6  8.4/7.6  
Pin/Package14CFP, 20LCCC, 8CDIP  14SOIC, 8PDIP, 8SOIC  14SOIC, 8PDIP, 8SOIC  
Regulated Outputs(#)1  1  1  
 SamplesSamplesSamples
 InventoryInventoryInventory

Other qualified versions of UC3845

Version Part Number Definition
Military UC1845 QML certified for Military and Defense Applications

Product Information

Features

  • Optimized For Off-line and DC-to-DC Converters
  • Low Start-Up Current (<1 mA)
  • Automatic Feed ForwardCompensation
  • Pulse-by-Pulse Current Limiting
  • Enhanced Load Response Characteristics
  • Under-Voltage Lockout With Hysteresis
  • Double Pulse Suppression
  • High Current Totem Pole Output
  • Internally Trimmed Bandgap Reference
  • 500-kHz Operation
  • Low RO Error Amp

Description

The UC1842/3/4/5 family of control devices provides the necessary features to implement off-line or dc-to-dc fixed frequency current mode control schemes with a minimal external parts count. Internally implemented circuits include under-voltage lockout featuring start up current less than 1 mA, a precision reference trimmed for accuracy at the error amp input, logic to insure latched operation, a PWM comparator which also provides current limit control, and a totem pole output stage designed to source or sink high peak current. The output stage, suitable for driving N-Channel MOSFETs, is low in the off state.

Differences between members of this family are the under-voltage lockout thresholds and maximum duty cycle ranges. The UC1842 and UC1844 have UVLO thresholds of 16 VON and 10 VOFF, ideally suited to off-line applications. The corresponding thresholds for the UC1843 and UC1845 are 8.4 V and 7.6 V. The UC1842 and UC1843 can operate to duty cycles approaching 100%. A range of zero to 50% is obtained by the UC1844 and UC1845 by the addition of an internal toggle flip flop which blanks the output off every other clock cycle.

    

Pricing / Packaging / CAD Design Tools / Samples

PricePackagingCAD Design ToolsSamples
DeviceStatusTemp (oC)Price | QuantityPackage | PinsTop Side MarkingPackage QTY | Package CarrierSymbolsFootprintsSamples
UC3845DACTIVE0 to 701.05 | 1kuSOIC (D) | 14 View 50 | TUBE Download CAD Format for this Symbol Download CAD Format for this Footprint
UC3845D8ACTIVE0 to 701.05 | 1kuSOIC (D) | 8 View 75 | TUBE Download CAD Format for this Symbol Download CAD Format for this Footprint
UC3845D8G4ACTIVE0 to 701.05 | 1kuSOIC (D) | 8 View 75 | TUBE Download CAD Format for this Symbol Download CAD Format for this Footprint
UC3845D8TRACTIVE0 to 700.90 | 1kuSOIC (D) | 8 View 2500 | LARGE T&R Download CAD Format for this Symbol Download CAD Format for this FootprintPurchase Samples
UC3845D8TRG4ACTIVE0 to 700.90 | 1kuSOIC (D) | 8 View 2500 | LARGE T&R Download CAD Format for this Symbol Download CAD Format for this FootprintPurchase Samples
UC3845DG4ACTIVE0 to 701.05 | 1kuSOIC (D) | 14 View 50 | TUBE Download CAD Format for this Symbol Download CAD Format for this Footprint
UC3845DTRACTIVE0 to 700.90 | 1kuSOIC (D) | 14 View 2500 | LARGE T&R Download CAD Format for this Symbol Download CAD Format for this FootprintPurchase Samples
UC3845DTRG4ACTIVE0 to 700.90 | 1kuSOIC (D) | 14 View 2500 | LARGE T&R Download CAD Format for this Symbol Download CAD Format for this FootprintPurchase Samples
UC3845NACTIVE0 to 700.90 | 1kuPDIP (P) | 8 View 50 | TUBE Download CAD Format for this Symbol Download CAD Format for this Footprint
UC3845NG4ACTIVE0 to 700.90 | 1kuPDIP (P) | 8 View 50 | TUBE Download CAD Format for this Symbol Download CAD Format for this Footprint
UC3845POBSOLETE0 to 70 PDIP (P) | 8 View    Download CAD Format for this FootprintNot Available

* Suggested Resale Price per unit (USD) for BUDGETARY USE ONLY. For higher volume price quotes,prices in local currency or delivery quotes, please contact your local Texas Instruments Sales Office or Authorized Distributor.

Inventory

Reported Distributor Inventory as of 9:48 AM GMT, 08 Nov 2009
RegionCompanyIn StockPurchase
TI Lead Time*: 20 WeeksUC3845D
AmericasArrow 315
Avnet 547
Rochester Electronics >1k
EuropeAbacus Polar 200
Avnet-SILICA >1k
EBV Elektronik 6
Spoerle 450
WorldwideDigiKey 275
TI Lead Time*: 20 WeeksUC3845D8
AmericasArrow >1k
Avnet >1k
Newark 287
Rochester Electronics >1k
AsiaFarnell Asia 287
WPI 231
EuropeAvnet-SILICA 25
TI Lead Time*: 20 WeeksUC3845D8G4
AsiaFarnell Asia 448
EuropeFarnell 357
TI Lead Time*: 20 WeeksUC3845D8TR
None Reported
View Distributors
TI Lead Time*: 20 WeeksUC3845D8TRG4
None Reported
View Distributors
TI Lead Time*: 20 WeeksUC3845DG4
AsiaFarnell Asia >1k
EuropeFarnell >1k
WorldwideDigiKey  Available
TI Lead Time*: 20 WeeksUC3845DTR
WorldwideDigiKey  Available
TI Lead Time*: 20 WeeksUC3845DTRG4
WorldwideDigiKey  Available
TI Lead Time*: 20 WeeksUC3845N
AmericasArrow >1k
Avnet >1k
Newark 18
Rochester Electronics >1k
AsiaFarnell Asia 32
WPI 44
EuropeArrow Northern Europe 200
Avnet-SILICA 350
EBV Elektronik 16
Farnell 32
WorldwideMouser Electronics 82
TI Lead Time*: 20 WeeksUC3845NG4
AsiaFarnell Asia 353
EuropeEBV Elektronik >1k
Farnell 301
WorldwideMouser Electronics 319
View all Distributors  

** Lead time information is not available at this time. However, our information is updated daily so please check back with us soon. Please contact your preferred TI Authorized Distributor for additional information.

Quality & Lead (Pb)-Free Data

 Product ContentDPPM / MTBF / FIT Rate
DeviceEco Plan* Lead / Ball FinishMSL Rating / Peak ReflowDetailsDetails
UC3845D RoHS Compliant Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIMViewView
UC3845D8 RoHS Compliant Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIMViewView
UC3845D8G4 RoHS Compliant Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIMViewView
UC3845D8TR RoHS Compliant Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIMViewView
UC3845D8TRG4 RoHS Compliant Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIMViewView
UC3845DG4 RoHS Compliant Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIMViewView
UC3845DTR RoHS Compliant Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIMViewView
UC3845DTRG4 RoHS Compliant Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIMViewView
UC3845N RoHS Compliant Green (RoHS & no Sb/Br) CU NIPDAU N/A for Pkg TypeViewView
UC3845NG4 RoHS Compliant Green (RoHS & no Sb/Br) CU NIPDAU N/A for Pkg TypeViewView
UC3845P      View

* The planned eco-friendly classification: Pb-Free (RoHS) or Pb-Free (RoHS Exempt) or Green (RoHS & no Sb/Br) - please click on the Product Content Details "View" link in the table above for the latest availability information and additional product content details.

If the information you are requesting is not available online at this time, contact one of our Product Information Centers regarding the availability of this information.

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