Overview
The UC2844D 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 stage ideal for driving power MOSFETs. The UC2844D includes protective features such as input and reference undervoltage lockouts with hysteresis, cycle-by-cycle current limiting, and a latch for single pulse metering. It is available in a 14-pin SOIC (D) package and is Pb-free and RoHS compliant.
Key Specifications
| Specification | Value | Unit |
|---|---|---|
| Total Power Supply and Zener Current (ICC + IZ) | 30 | mA |
| Output Current, Source or Sink | 1.0 | A |
| Output Energy (Capacitive Load per Cycle) | 5.0 | mJ |
| Current Sense and Voltage Feedback Inputs | -0.3 to +5.5 | V |
| Error Amp Output Sink Current | 10 | mA |
| Maximum Power Dissipation @ TA = 25°C (D Suffix) | 862 mW | mW |
| Thermal Resistance Junction-to-Air (D Suffix) | 145 °C/W | °C/W |
| Operating Junction Temperature | -40 to 85 | °C |
| Operating Ambient Temperature | -40 to 85 | °C |
| Oscillator Frequency | Up to 500 kHz | kHz |
| UVLO Thresholds | 16 V (on), 10 V (off) | V |
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
- Input Undervoltage Lockout with Hysteresis
- Low Startup and Operating Current (< 1 mA)
- Direct Interface with ON Semiconductor SENSEFET Products
- Pb-Free Packages and RoHS Compliant
Applications
The UC2844D is optimized for use in off-line and DC-to-DC converter applications. It is suitable for various power supply designs, including boost, buck, flyback, and forward regulators. Its features make it particularly useful in applications requiring high efficiency, minimal external components, and robust protective features.
Q & A
- What is the primary function of the UC2844D?
The UC2844D 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 UC2844D?
The UVLO thresholds for the UC2844D are 16 V (on) and 10 V (off).
- What is the maximum output switching frequency of the UC2844D?
The maximum output switching frequency of the UC2844D is up to 500 kHz.
- What type of output stage does the UC2844D have?
The UC2844D has a high-current totem pole output stage.
- What are the operating temperature ranges for the UC2844D?
The operating temperature range for the UC2844D is -40°C to 85°C.
- Does the UC2844D support Pb-free and RoHS compliance?
Yes, the UC2844D is Pb-free and RoHS compliant.
- What types of converters can the UC2844D be used in?
The UC2844D can be used in boost, buck, flyback, and forward regulators.
- What is the purpose of the undervoltage lockout feature in the UC2844D?
The undervoltage lockout feature ensures that the IC is fully functional before the output stage is enabled, preventing erratic output behavior.
- How is the oscillator frequency programmed in the UC2844D?
The oscillator frequency is programmed by the values selected for the timing components RT and CT.
- What is the typical startup current of the UC2844D?
The typical startup current of the UC2844D is less than 1 mA.
