Overview
The STMicroelectronics UC3845BN is a high-performance current mode PWM (Pulse Width Modulation) controller designed for use in switch mode power supplies. This component is particularly suited for off-line and DC-DC converter applications, offering a cost-effective solution with minimal external components. The UC3845BN features a fixed frequency operation and is available in an 8-pin PDIP package. It integrates various protective features such as input and reference undervoltage lockouts, cycle-by-cycle current limiting, and a latch for single pulse metering, enhancing its robustness and reliability.
Key Specifications
| Specification | Description |
|---|---|
| Brand | STMicroelectronics |
| Maximum Switching Frequency | 500 kHz |
| Output Current | 1 A |
| Control Method | Current Mode |
| Number of Outputs | 1 |
| Mounting Type | Through Hole |
| Package Type | PDIP |
| Pin Count | 8 |
| Topology | Boost, Flyback |
| Maximum Duty Cycle | 50% |
| Dimensions | 10.92 x 6.6 x 3.32 mm |
| Minimum Operating Temperature | -40 °C |
| Maximum Operating Temperature | +150 °C |
| Rise Time | 50 ns |
| Fall Time | 50 ns |
Key Features
- High-performance current mode PWM controller with a fixed frequency operation of up to 500 kHz.
- Integrated oscillator with a precision reference voltage for accurate duty cycle control.
- High gain error amplifier and current sensing comparator for precise control over the output switch conduction.
- Protective features including input and reference undervoltage lockouts, cycle-by-cycle current limiting, and a latch for single pulse metering.
- A flip-flop that blanks the output off every other clock cycle, allowing for programmable output deadtimes.
- High current totem pole output suitable for driving power MOSFETs.
- Compact 8-pin PDIP package.
Applications
- Off-line and DC-DC converter applications.
- Switch mode power supplies (SMPS) including isolated and non-isolated AC-DC and DC-DC configurations.
- Single-ended topologies such as fly-back, forward, and quasi-resonant controllers.
- Double-ended configurations like asymmetrical half-bridge controllers.
Q & A
- What is the maximum switching frequency of the UC3845BN?
The maximum switching frequency of the UC3845BN is 500 kHz.
- What is the control method used by the UC3845BN?
The UC3845BN uses a current mode control method.
- What are the typical applications of the UC3845BN?
The UC3845BN is typically used in off-line and DC-DC converter applications, including switch mode power supplies (SMPS).
- What protective features are integrated into the UC3845BN?
The UC3845BN includes protective features such as input and reference undervoltage lockouts, cycle-by-cycle current limiting, and a latch for single pulse metering.
- What is the package type and pin count of the UC3845BN?
The UC3845BN is available in an 8-pin PDIP package.
- What are the operating temperature ranges for the UC3845BN?
The UC3845BN operates within a temperature range of -40 °C to +150 °C.
- How does the UC3845BN control output deadtimes?
The UC3845BN uses an internal flip-flop to blank the output off every other clock cycle, allowing for programmable output deadtimes.
- What is the typical output current of the UC3845BN?
The typical output current of the UC3845BN is 1 A.
- What topologies does the UC3845BN support?
The UC3845BN supports boost and flyback topologies.
- What is the maximum duty cycle of the UC3845BN?
The maximum duty cycle of the UC3845BN is 50%.
