UC2845B: High Performance Current Mode PWM Controller

Description: The UC3844B, UC3845B series are high performance f...
  • The UC3844B, UC3845B series are high performance fixed frequency current mode controllers. They are specifically designed for Off-Line and dc-to-dc converter applications offering the designer a cost-effective solution with minimal external components. These integrated circuits feature an oscillator, a temperature compensated reference, high gain error amplifier, current sensing comparator, and a high current totem pole output ideally suited for driving a power MOSFET.

    Also included are protective features consisting of input and reference undervoltage lockouts each with hysteresis, cycle-by-cycle current limiting, a latch for single pulse metering, and a flip-flop which blanks the output off every other oscillator cycle, allowing output deadtimes to be programmed from 50% to 70%.

    These devices are available in an 8-pin dual-in-line and surface mount (SO-8) plastic package as well as the 14-pin plastic surface mount (SO-14). The SO-14 package has separate power and ground pins for the totem pole output stage.

    The UCX844B has UVLO thresholds of 16 V (on) and 10 V (off), ideally suited for off-line converters. The UCX845B is tailored for lower voltage applications having UVLO thresholds of 8.5 V (on) and 7.6 V (off).
  • Features
  • Trimmed Oscillator for Precise Frequency Control
  • Oscillator Frequency Guaranteed at 250 kHz
  • Current Mode Operation to 500 kHz Output Switching Frequency
  • Output Deadtime Adjustable from 50% to 70%
  • Automatic Feed Forward Compensation
  • Latching PWM for Cycle-By-Cycle Current Limiting
  • Internally Trimmed Reference with Undervoltage Lockout
  • High Current Totem Pole Output
  • Undervoltage Lockout with Hysteresis
  • Low Startup and Operating Current
  • Pb-Free Packages are Available
  • Technical Documentation & Design Resources
    Product Change Notification
    Availability and Samples
    UC2845BD1G
  • Status: Active
  • Compliance: Pb-free Halide free 
  • Description: High Performance Current Mode PWM Controller
  • Package Type: SOIC-8
  • Package Case Outline: 751-07
  • MSL: 1
  • Container Type: TUBE
  • Container Qty: 98
  • Inventory

  • Market Leadtime (weeks):2 to 4
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  • PandS:<1K
  • UC2845BD1R2G
  • Status: Active
  • Compliance: Pb-free Halide free 
  • Description: High Performance Current Mode PWM Controller
  • Package Type: SOIC-8
  • Package Case Outline: 751-07
  • MSL: 1
  • Container Type: REEL
  • Container Qty: 2500
  • Inventory

  • Market Leadtime (weeks):Contact Factory
  • Arrow:0
  • Digikey:>1K
  • Newark:>1K
  • ON Semiconductor:17,500
  • PandS:>10K
  • Wpi:>10K
  • UC2845BDG
  • Status: Active
  • Compliance: Pb-free Halide free 
  • Description: High Performance Current Mode PWM Controller
  • Package Type: SOIC-14
  • Package Case Outline: 751A-03
  • MSL: 1
  • Container Type: TUBE
  • Container Qty: 55
  • Inventory

  • Market Leadtime (weeks):2 to 4
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  • Digikey:<1K
  • ON Semiconductor:10,780
  • PandS:<100
  • UC2845BDR2G
  • Status: Active
  • Compliance: Pb-free Halide free 
  • Description: High Performance Current Mode PWM Controller
  • Package Type: SOIC-14
  • Package Case Outline: 751A-03
  • MSL: 1
  • Container Type: REEL
  • Container Qty: 2500
  • Inventory

  • Market Leadtime (weeks):4 to 8
  • Arrow:0
  • Digikey:>1K
  • UC2845BNG
  • Status: Active
  • Compliance: Pb-free Halide free 
  • Description: High Performance Current Mode PWM Controller
  • Package Type: PDIP-8
  • Package Case Outline: 626-05
  • MSL: NA
  • Container Type: TUBE
  • Container Qty: 50
  • Inventory

  • Market Leadtime (weeks):17 to 20
  • Arrow:0
  • Digikey:<1K
  • Newark:<100
  • ON Semiconductor:73,700
  • PandS:>10K
  • Specifications
  • Topology: Flyback 
  • Control Mode: Current Mode 
  • fsw Typ (kHz): 52 
  • Stand-by Mode: No 
  • UVLO (V): Yes 
  • Short Circuit Protection: Yes 
  • Latch: No 
  • Soft Start: No 
  • VCC Max (V): 30 
  • Drive Cap. (mA): 200 / 200 
  • Package Type: SOIC-8  SOIC-14  PDIP-8 
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