Overview
The UC3845NG4 is a fixed frequency current-mode PWM (Pulse Width Modulation) controller produced by Texas Instruments. This integrated circuit is specifically designed for off-line and DC to DC converter applications, requiring minimal external components. It features a trimmed oscillator for precise duty cycle control, a temperature-compensated reference, a high gain error amplifier, a current sensing comparator, and a high current totem-pole output for driving a Power MOSFET.
Key Specifications
| Category | Description |
|---|---|
| Manufacturer | Texas Instruments |
| Package / Case | 8-DIP (0.300", 7.62mm) |
| Mounting Type | Through Hole |
| Function | Step-Up, Step-Down, Step-Up/Step-Down |
| Topology | Boost, Buck, Buck-Boost, Flyback, Forward |
| Clock Sync | No |
| Output Type | Transistor Driver |
| Output Phases | 1 |
| Number of Outputs | 1 |
| Output Configuration | Positive, Isolation Capable |
| Frequency - Switching | Up to 500kHz |
| Operating Temperature | 0°C ~ 70°C (TA) |
| Synchronous Rectifier | No |
| Voltage - Supply (Vcc/Vdd) | 12V ~ 28V |
| Duty Cycle (Max) | 48% |
| Control Features | Frequency Control |
Key Features
- Low Start-Up Current: Ensures efficient operation from the start.
- Maximum Duty Clamp: Provides precise control over the duty cycle.
- UVLO With Hysteresis: Under-Voltage Lockout with hysteresis for reliable operation.
- High Gain Error Amplifier: Enhances the accuracy of the feedback loop.
- Current Sensing Comparator: Allows for accurate current sensing and control.
- High Current Totem-Pole Output: Capable of driving Power MOSFETs efficiently.
- Frequency Control: Supports operating frequencies up to 500kHz.
Applications
- Off-Line and DC to DC Converters: Ideal for various power supply applications.
- Boost, Buck, Buck-Boost, Flyback, and Forward Converters: Versatile topology support.
- Isolation Capable Outputs: Suitable for applications requiring isolated outputs.
Q & A
- What is the primary function of the UC3845NG4?
The UC3845NG4 is a fixed frequency current-mode PWM controller designed for off-line and DC to DC converter applications.
- What are the supported topologies for the UC3845NG4?
The UC3845NG4 supports Boost, Buck, Buck-Boost, Flyback, and Forward converter topologies.
- What is the maximum operating frequency of the UC3845NG4?
The UC3845NG4 can operate at frequencies up to 500kHz.
- What is the maximum duty cycle for the UC3845NG4?
The maximum duty cycle for the UC3845NG4 is 48%.
- Does the UC3845NG4 support synchronous rectification?
No, the UC3845NG4 does not support synchronous rectification.
- What is the operating temperature range for the UC3845NG4?
The operating temperature range for the UC3845NG4 is 0°C to 70°C.
- What type of output does the UC3845NG4 provide?
The UC3845NG4 provides a transistor driver output.
- Is the UC3845NG4 RoHS compliant?
- What is the supply voltage range for the UC3845NG4?
The supply voltage range for the UC3845NG4 is 12V to 28V.
- What are some key features of the UC3845NG4?
The UC3845NG4 features low start-up current, maximum duty clamp, UVLO with hysteresis, high gain error amplifier, and high current totem-pole output.
