UC3845BD1R2G ON IC Integrated Circuit CHIP High Performance Current
Mode Controllers
High Performance Current Mode Controllers
The UC3844B, UC3845B series are high performance fixed frequency
current mode controllers. They are specifically designed for
Off−Line and dc−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 (SOIC−8) plastic package as well as the 14−pin plastic
surface mount (SOIC−14). The SOIC−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
• Pb−Free Packages are Available
• 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
| Product Attributes | Select All |
| Manufacturer | ON Semiconductor |
| Series | - |
| Packaging | Tape & Reel (TR) |
| Part Status | Active |
| Output Type | Transistor Driver |
| Function | Step-Up, Step-Up/Step-Down |
| Output Configuration | Positive or Negative, Isolation Capable |
| Topology | Boost, Flyback |
| Number of Outputs | 1 |
| Output Phases | 1 |
| Voltage - Supply (Vcc/Vdd) | 7.6 V ~ 30 V |
| Frequency - Switching | 500kHz |
| Duty Cycle (Max) | 0.48 |
| Synchronous Rectifier | No |
| Clock Sync | No |
| Serial Interfaces | - |
| Control Features | Frequency Control |
| Operating Temperature | 0°C ~ 70°C (TA) |
| Package / Case | 8-SOIC (0.154", 3.90mm Width) |
| Supplier Device Package | 8-SOIC |
| Base Part Number | UC384*B |
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