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 |
