Overview
The UC3844BVDR2 is a high-performance, fixed-frequency current mode controller produced by onsemi. It is specifically designed for off-line and DC-to-DC converter applications, offering a cost-effective solution with minimal external components. This integrated circuit features an oscillator, a temperature-compensated reference, a high-gain error amplifier, a current sensing comparator, and a high-current totem pole output, making it ideal for driving power MOSFETs.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Oscillator Frequency | - | 250 kHz | - | kHz |
| Output Switching Frequency | - | - | 500 kHz | kHz |
| Output Deadtime Adjustable | 50% | - | 70% | % |
| UVLO Thresholds (UC3844) | 10 V (off) | - | 16 V (on) | V |
| UVLO Thresholds (UC3845) | 7.6 V (off) | - | 8.5 V (on) | V |
| Output Voltage Swing High State | 5.0 V | - | 6.2 V | V |
| Output Voltage Swing Low State | 0.8 V | - | 1.1 V | V |
| Current Sense Input Voltage Gain | 2.85 V/V | 3.0 V/V | 3.15 V/V | V/V |
| Maximum Current Sense Input Threshold | 0.9 V | 1.0 V | 1.1 V | V |
| Power Supply Rejection Ratio | - | 70 dB | - | dB |
| Propagation Delay (Current Sense Input to Output) | 150 ns | - | 300 ns | ns |
| Operating Temperature Range | 0°C | - | 70°C | °C |
Key Features
- Current Mode Operation up 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 and RoHS Compliant
- AEC-Q100 Qualified and PPAP Capable for Automotive and Other Applications
Applications
The UC3844BVDR2 is designed for various power conversion applications, including:
- Off-Line Converters: Ideal for applications requiring efficient bootstrap startup techniques.
- DC-to-DC Converters: Suitable for high-performance DC-to-DC conversion with minimal external components.
- Power Supplies: Used in switched-mode power supplies for efficient and reliable operation.
- Automotive Systems: AEC-Q100 qualified, making it suitable for automotive and other demanding applications.
Q & A
- What is the primary function of the UC3844BVDR2?
The UC3844BVDR2 is a high-performance, fixed-frequency current mode controller designed for off-line and DC-to-DC converter applications.
- What is the typical oscillator frequency of the UC3844BVDR2?
The oscillator frequency is typically 250 kHz.
- How is the output deadtime adjustable on the UC3844BVDR2?
The output deadtime can be adjusted from 50% to 70%.
- What protective features does the UC3844BVDR2 include?
It includes input and reference undervoltage lockouts with hysteresis, cycle-by-cycle current limiting, and a latch for single pulse metering.
- What are the UVLO thresholds for the UC3844 and UC3845?
For UC3844, the UVLO thresholds are 16 V (on) and 10 V (off). For UC3845, the thresholds are 8.5 V (on) and 7.6 V (off).
- What is the power supply rejection ratio of the UC3844BVDR2?
The power supply rejection ratio is 70 dB.
- What is the propagation delay from the current sense input to the output?
The propagation delay is between 150 ns and 300 ns.
- Is the UC3844BVDR2 RoHS compliant?
Yes, the UC3844BVDR2 is Pb-Free and RoHS compliant.
- What are the typical operating temperature ranges for the UC3844BVDR2?
The operating temperature range is from 0°C to 70°C.
- What types of packages are available for the UC3844BVDR2?
The device is available in 8-pin dual-in-line and surface mount (SOIC-8 and SOIC-14) packages.
