Overview
The UC3845BD1, produced by STMicroelectronics, is a high-performance current mode PWM controller. This IC is part of the UC384xB family, which is designed for off-line and DC-DC converter applications. It offers a cost-effective solution with a minimal external parts count, making it ideal for various power supply designs. The UC3845BD1 features a trimmed oscillator for precise frequency control, automatic feed-forward compensation, and a high current totem pole output stage suitable for driving N-Channel MOSFETs.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Supply Voltage (Vi) | - | - | 30 | V |
| Output Current (IO) | - | - | ±1 A | A |
| Output Energy (Capacitive Load) | - | - | 5 µJ | µJ |
| Reference Output Voltage (Vref) | 4.95 | 5.00 | 5.05 | V |
| Line Regulation | -2 | - | 20 | mV |
| Load Regulation | -3 | - | 25 | mV |
| Temperature Stability | -0.2 | - | - | mV/°C |
| Oscillator Frequency | - | - | 250 kHz | kHz |
| Maximum Duty Cycle | 47 | 48 | 50 | % |
| Under-Voltage Lockout Start Threshold | 7.8 | 8.4 | 9.0 | V |
| Minimum Operating Voltage After Turn-on | 7.0 | 7.6 | 8.2 | V |
| Start-up Current | 0.3 | 0.5 | 0.5 | mA |
| Operating Supply Current | 12 | 17 | 17 | mA |
Key Features
- Trimmed Oscillator: Provides precise frequency control up to 250 kHz.
- Current Mode Operation: Supports operation up to 500 kHz.
- Automatic Feed-Forward Compensation: Enhances stability and performance.
- Latching PWM for Cycle-by-Cycle Current Limiting: Ensures robust current control.
- Internally Trimmed Reference with Under-Voltage Lockout: Includes hysteresis for reliable start-up and operation.
- High Current Totem Pole Output: Suitable for driving N-Channel MOSFETs with high peak current capability.
- ESD Protection and Latch-Up Protection: Meets JEDEC standards for robustness against electrical stress.
- Low Start-Up and Operating Current: Minimizes power consumption during start-up and operation.
Applications
- Off-Line Power Supplies: Ideal for designing efficient and reliable off-line power supplies.
- DC-DC Converters: Suitable for various DC-DC converter applications requiring high performance and minimal external components.
- Switch Mode Power Supplies: Used in switch mode power supplies where precise current mode control is necessary.
- Industrial Power Systems: Applicable in industrial power systems requiring robust and efficient power management.
Q & A
- What is the primary function of the UC3845BD1?
The UC3845BD1 is a high-performance current mode PWM controller designed for off-line and DC-DC converter applications.
- What is the typical oscillator frequency of the UC3845BD1?
The oscillator frequency is typically 250 kHz.
- What is the maximum duty cycle for the UC3845BD1?
The maximum duty cycle is up to 50%.
- What are the under-voltage lockout thresholds for the UC3845BD1?
The start threshold is between 7.8V and 9.0V, and the minimum operating voltage after turn-on is between 7.0V and 8.2V.
- What is the output current capability of the UC3845BD1?
The output current can source or sink up to ±1 A.
- Does the UC3845BD1 have ESD protection?
Yes, it includes ESD protection exceeding JEDEC standards.
- What is the typical operating supply current for the UC3845BD1?
The typical operating supply current is around 17 mA.
- What type of output stage does the UC3845BD1 have?
The UC3845BD1 has a high current totem pole output stage.
- Is the UC3845BD1 suitable for driving N-Channel MOSFETs?
Yes, it is specifically designed to drive N-Channel MOSFETs.
- What are some common applications of the UC3845BD1?
Common applications include off-line power supplies, DC-DC converters, and switch mode power supplies.
