Overview
The UC3845BD1R2 is a high-performance, fixed-frequency current mode controller produced by onsemi. This integrated circuit is specifically designed for off-line and DC-DC converter applications, offering a cost-effective solution with minimal external components. It features a range of protective and functional elements, including an oscillator, a temperature-compensated reference, a high-gain error amplifier, a current sensing comparator, and a high-current totem pole output stage. This makes it ideal for driving power MOSFETs in various power supply designs.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Number of Outputs | 1 | - | - | - |
| Switching Frequency | 250 | - | 500 | kHz |
| Duty Cycle - Max | - | 50% | - | % |
| Output Voltage | 4.9 | 5.0 | 5.1 | V |
| Reference Output Voltage | 4.95 | 5.0 | 5.05 | V |
| Operating Junction Temperature | -40 | - | 150 | °C |
| Operating Ambient Temperature | -25 | - | 85 | °C |
| Storage Temperature Range | -65 | - | 150 | °C |
Key Features
- Trimmed Oscillator for Precise Frequency Control: The oscillator frequency can be precisely controlled using external timing components RT and CT.
- Current Mode Operation: Supports switching frequencies up to 500 kHz.
- Adjustable Output Deadtime: Output deadtime can be adjusted from 50% to 70%.
- Automatic Feed Forward Compensation: Enhances stability and performance.
- Latching PWM for Cycle-by-Cycle Current Limiting: Ensures safe operation by limiting peak inductor current on a cycle-by-cycle basis.
- Internally Trimmed Reference with Undervoltage Lockout: Provides a stable reference voltage and protects against undervoltage conditions.
- High Current Totem Pole Output: Capable of sourcing and sinking peak currents up to 1.0 A.
- Undervoltage Lockout with Hysteresis: Prevents erratic output behavior by monitoring VCC and Vref with built-in hysteresis.
- Low Startup and Operating Current: Minimizes power consumption during startup and operation.
- Pb-Free and RoHS Compliant: Meets environmental standards for lead-free and RoHS compliance.
Applications
The UC3845BD1R2 is suitable for a variety of applications, including:
- Off-Line and DC-DC Converters: Ideal for designing cost-effective power supplies with minimal external components.
- Power MOSFET Drivers: High-current totem pole output stage makes it suitable for driving power MOSFETs.
- Switch Mode Power Supplies: Used in switch mode power supplies due to its current mode operation and adjustable output deadtime.
- Automotive and Industrial Power Systems: Can be used in automotive and industrial applications requiring robust and reliable power management.
Q & A
- What is the primary function of the UC3845BD1R2?
The UC3845BD1R2 is a high-performance, fixed-frequency current mode controller designed for off-line and DC-DC converter applications.
- What is the typical switching frequency of the UC3845BD1R2?
The typical switching frequency is 250 kHz, but it can operate up to 500 kHz.
- How is the output deadtime adjusted in the UC3845BD1R2?
The output deadtime can be adjusted from 50% to 70% using internal circuitry.
- What protective features does the UC3845BD1R2 include?
It includes undervoltage lockout with hysteresis, cycle-by-cycle current limiting, and latch for single pulse metering.
- What is the maximum output current of the UC3845BD1R2?
The output stage can source and sink peak currents up to 1.0 A.
- Is the UC3845BD1R2 Pb-Free and RoHS compliant?
- What are the operating temperature ranges for the UC3845BD1R2?
The operating junction temperature range is -40°C to 150°C, and the operating ambient temperature range is -25°C to 85°C.
- How is the oscillator frequency controlled in the UC3845BD1R2?
The oscillator frequency is controlled using external timing components RT and CT.
- What is the purpose of the undervoltage lockout in the UC3845BD1R2?
The undervoltage lockout ensures that the IC is fully functional before the output stage is enabled, preventing erratic output behavior.
- Can the UC3845BD1R2 be used in automotive applications?
