Overview
The UC2843BD is a high-performance fixed frequency current mode controller produced by onsemi. It is specifically designed for Off-Line and DC-DC converter applications, offering a cost-effective solution with minimal external components. This integrated circuit features a trimmed oscillator for precise duty cycle control, a temperature-compensated reference, a high gain error amplifier, a current sensing comparator, and a high current totem pole output ideal for driving a power MOSFET.
The device includes protective features such as input and reference undervoltage lockouts with hysteresis, cycle-by-cycle current limiting, programmable output deadtime, and a latch for single pulse metering. The UC2843BD is available in 8-pin and 14-pin surface mount packages, with the 14-pin package having separate power and ground pins for the totem pole output stage.
Key Specifications
| Characteristics | Symbol | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| Reference Output Voltage (IO = 1.0 mA, TJ = 25°C) | Vref | 4.95 | 5.0 | 5.05 | V |
| Oscillator Frequency (TJ = 25°C) | fOSC | 48 | 250 | 275 | kHz |
| Output Current, Source or Sink | IO | - | - | 1.0 | A |
| Startup Threshold (VCC) | Vth | 8.5 | - | 9.0 | V |
| Minimum Operating Voltage After Turn-On (VCC) | VCC(min) | 7.0 | - | 8.2 | V |
| Power Supply Current (Startup) | ICC + IC | - | - | 0.3 | mA |
| Output Voltage Rise Time (CL = 1.0 nF, TJ = 25°C) | tr | - | 50 | 150 | ns |
| Output Voltage Fall Time (CL = 1.0 nF, TJ = 25°C) | tf | - | 50 | 150 | ns |
Key Features
- Trimmed Oscillator for Precise Frequency Control
- Oscillator Frequency Guaranteed at 250 kHz
- Current Mode Operation up to 500 kHz
- 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 Halide-Free Device
Applications
The UC2843BD is designed for Off-Line and DC-DC converter applications. It is particularly suited for:
- Switch Mode Power Supplies
- DC-DC Converters
- High Efficiency Power Conversion Systems
- Cost-Effective Solutions Requiring Minimal External Components
Q & A
- What is the primary function of the UC2843BD?
The UC2843BD is a high-performance fixed frequency current mode controller designed for Off-Line and DC-DC converter applications.
- What are the key features of the UC2843BD?
Key features include a trimmed oscillator, current mode operation up to 500 kHz, automatic feed forward compensation, latching PWM, internally trimmed reference, high current totem pole output, and undervoltage lockout with hysteresis.
- What are the typical operating voltage ranges for the UC2843BD?
The startup threshold is 8.5 V, and the minimum operating voltage after turn-on is 7.0 V.
- What is the maximum output current of the UC2843BD?
The maximum output current is 1.0 A.
- What are the package options for the UC2843BD?
The device is available in 8-pin and 14-pin surface mount packages.
- What protective features does the UC2843BD include?
Protective features include input and reference undervoltage lockouts with hysteresis, cycle-by-cycle current limiting, programmable output deadtime, and a latch for single pulse metering.
- What is the oscillator frequency range of the UC2843BD?
The oscillator frequency is guaranteed at 250 kHz.
- How is the oscillator frequency programmed in the UC2843BD?
The oscillator frequency is programmed by the values chosen for the timing components RT and CT.
- What is the typical DC voltage gain of the error amplifier in the UC2843BD?
The typical DC voltage gain of the error amplifier is 90 dB.
- Is the UC2843BD Pb-Free and Halide-Free?
Yes, the UC2843BD is a Pb-Free and Halide-Free device.
