Overview
The UC3845BVDG is a high-performance fixed frequency current mode controller produced by onsemi. It is part of the UC3844B and UC3845B series, which are specifically designed for off-line and dc-to-dc converter applications. These controllers offer a cost-effective solution with minimal external components, making them ideal for a variety of power management needs.
The UC3845BVDG features an oscillator, a temperature-compensated reference, a high-gain error amplifier, a current sensing comparator, and a high current totem pole output. This device is particularly suited for driving power MOSFETs and includes several protective features such as input and reference undervoltage lockouts, cycle-by-cycle current limiting, and adjustable output deadtimes.
Key Specifications
| Characteristic | Symbol | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| Reference Output Voltage | Vref | 4.95 | 5.0 | 5.05 | V |
| Oscillator Frequency | fOSC | - | 250 kHz | - | kHz |
| Output Switching Frequency | fSW | - | up to 500 kHz | - | kHz |
| UVLO Thresholds | UVLO | 7.6 V (off), 8.5 V (on) | - | - | V |
| Output Deadtime Adjustable | - | 50% to 70% | - | - | % |
| High Current Totem Pole Output | - | - | - | - | - |
| Power Supply Current | ICC | - | 0.3 mA (Startup), 12 mA (Operating) | - | mA |
| Package Type | - | SOIC-14 | - | - | - |
Key Features
- 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
- Pb-Free Packages are Available and RoHS Compliant
Applications
The UC3845BVDG is designed for various power management applications, including:
- Off-Line Converters
- DC-to-DC Converters
- Power Supplies
- Switch Mode Power Supplies
- High-Efficiency Power Conversion Systems
Q & A
- What is the primary function of the UC3845BVDG?
The UC3845BVDG is a high-performance fixed frequency current mode controller designed for off-line and dc-to-dc converter applications.
- What are the UVLO thresholds for the UC3845BVDG?
The UVLO thresholds for the UC3845BVDG are 7.6 V (off) and 8.5 V (on).
- What is the oscillator frequency of the UC3845BVDG?
The oscillator frequency is guaranteed at 250 kHz.
- What is the maximum output switching frequency of the UC3845BVDG?
The maximum output switching frequency is up to 500 kHz.
- What protective features does the UC3845BVDG include?
The device includes input and reference undervoltage lockouts, cycle-by-cycle current limiting, and a latch for single pulse metering.
- What package types are available for the UC3845BVDG?
The UC3845BVDG is available in an 8-pin dual-in-line and surface mount (SOIC-8) as well as a 14-pin plastic surface mount (SOIC-14) package.
- Is the UC3845BVDG RoHS compliant?
- What is the typical power supply current for the UC3845BVDG?
The typical power supply current is 0.3 mA during startup and 12 mA during operation.
- Can the output deadtime be adjusted on the UC3845BVDG?
- What is the purpose of the high current totem pole output in the UC3845BVDG?
The high current totem pole output is ideally suited for driving a power MOSFET.
