Overview
The UC2844AM is a high-performance current mode controller integrated circuit produced by Microsemi Corporation. It is part of the UC2844 and UC3844 series, designed for off-line and DC-to-DC converter applications. This IC offers a cost-effective solution with minimal external components, making it ideal for a variety of power supply designs.
The UC2844AM features a fixed frequency oscillator, a temperature-compensated reference, a high-gain error amplifier, a current sensing comparator, and a high current totem pole output. These features make it well-suited for driving power MOSFETs in high-efficiency switching power supplies.
Key Specifications
| Rating | Symbol | Value | Unit |
|---|---|---|---|
| Total Power Supply and Zener Current | ICC + IZ | 30 | mA |
| Output Current, Source or Sink | IO | 1.0 | A |
| Output Energy (Capacitive Load per Cycle) | W | 5.0 | mJ |
| Current Sense and Voltage Feedback Inputs | Vin | −0.3 to +5.5 | V |
| Error Amp Output Sink Current | IO | 10 | mA |
| Operating Junction Temperature | TJ | −25 to +85 | °C |
| Storage Temperature Range | Tstg | −65 to +150 | °C |
| Reference Output Voltage | Vref | 4.95 to 5.05 | V |
| Startup Threshold | Vth | 16 | V |
| Minimum Operating Voltage After Turn-On | VCC(min) | 10 | 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
- Direct Interface with ON Semiconductor SENSEFET Products
- Pb-Free Packages Available
Applications
The UC2844AM is specifically designed for off-line and DC-to-DC converter applications. It is suitable for use in:
- Switching Power Supplies
- DC-DC Converters
- High-Efficiency Power Supplies
- Power Factor Correction (PFC) Circuits
- Other High-Performance Power Conversion Systems
Q & A
- What is the primary function of the UC2844AM?
The UC2844AM is a high-performance current mode controller designed for off-line and DC-to-DC converter applications.
- What is the maximum output switching frequency of the UC2844AM?
The UC2844AM can operate up to 500 kHz output switching frequency.
- What are the key protective features of the UC2844AM?
The IC includes input and reference undervoltage lockouts with hysteresis, cycle-by-cycle current limiting, and a latch for single pulse metering.
- How is the oscillator frequency programmed in the UC2844AM?
The oscillator frequency is programmed by the values selected for the timing components RT and CT.
- What is the purpose of the totem pole output in the UC2844AM?
The totem pole output is designed to drive power MOSFETs efficiently.
- What are the package options available for the UC2844AM?
The UC2844AM is available in an 8-pin dual-in-line plastic package and a 14-pin plastic surface mount (SOIC-14) package.
- What is the operating junction temperature range for the UC2844AM?
The operating junction temperature range is from −25°C to +85°C.
- How does the UC2844AM handle current sensing and limiting?
The IC uses a current sense comparator and PWM latch to control the inductor current on a cycle-by-cycle basis, with automatic clamping to prevent excessive current.
- What is the reference output voltage of the UC2844AM?
The reference output voltage is typically 5.0 V, with a range of 4.95 V to 5.05 V.
- Is the UC2844AM Pb-free?
