Overview
The UC3843ADR2, produced by onsemi, is a high-performance, fixed-frequency current mode controller. 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 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 stage ideal for driving power MOSFETs. The device includes protective features such as input and reference undervoltage lockouts, cycle-by-cycle current limiting, programmable output deadtime, and a latch for single pulse metering.
Key Specifications
| Parameter | Symbol | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| Reference Output Voltage | Vref | 4.95 | 5.0 | 5.05 | V |
| Line Regulation | Regline | -2.0 | - | 20 | mV |
| Load Regulation | Regload | -3.0 | - | 25 | mV |
| Temperature Stability | TS | -0.2 | - | - | mV/°C |
| Oscillator Frequency | fosc | 47 | 50 | 52 | kHz |
| Power Supply Rejection Ratio | PSRR | 60 | 70 | - | dB |
| Output Voltage Swing High State | VOH | 5.0 | - | 6.2 | V |
| Output Voltage Swing Low State | VOL | 0.8 | - | 1.1 | V |
| Operating Junction Temperature | TJ | - | - | 150 | °C |
| Operating Ambient Temperature | TA | 0 | - | 70 | °C |
Key Features
- Trimmed Oscillator Discharge Current: For precise duty cycle control.
- Current Mode Operation: Up to 500 kHz.
- Automatic Feed Forward Compensation: Enhances stability.
- Latching PWM for Cycle-by-Cycle Current Limiting: Ensures safe operation.
- Internally Trimmed Reference with Undervoltage Lockout: Provides stable reference voltage and protection.
- High Current Totem Pole Output: Suitable for driving power MOSFETs.
- Programmable Output Deadtime and Single Pulse Metering Latch: For flexible and reliable operation.
- Separate Power and Ground Pins for the Totem Pole Output Stage (SOIC-14 package): Improves noise immunity and performance.
Applications
The UC3843ADR2 is designed for various power supply applications, including:
- Off-line Converters: Suitable for high-voltage applications with UVLO thresholds of 8.5 V (on) and 7.6 V (off).
- DC-to-DC Converters: Ideal for applications requiring high efficiency and reliability.
- Switch Mode Power Supplies: Used in a wide range of SMPS designs due to its robust features and high performance.
Q & A
- What is the primary function of the UC3843ADR2?
The UC3843ADR2 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 UC3843ADR2?
The typical oscillator frequency is around 50 kHz, with a range of 47 kHz to 52 kHz.
- What are the UVLO thresholds for the UC3843ADR2?
The UVLO thresholds are 8.5 V (on) and 7.6 V (off).
- What type of output stage does the UC3843ADR2 have?
The UC3843ADR2 has a high-current totem pole output stage suitable for driving power MOSFETs.
- What protective features does the UC3843ADR2 include?
The device includes input and reference undervoltage lockouts, cycle-by-cycle current limiting, programmable output deadtime, and a latch for single pulse metering.
- What is the operating ambient temperature range for the UC3843ADR2?
The operating ambient temperature range is from 0°C to 70°C.
- What is the purpose of the internally trimmed reference in the UC3843ADR2?
The internally trimmed reference provides a stable reference voltage and includes undervoltage lockout protection.
- How is the oscillator frequency programmed in the UC3843ADR2?
The oscillator frequency is programmed by the values selected for the timing components RT and CT.
- What is the significance of the separate power and ground pins in the SOIC-14 package?
The separate power and ground pins improve noise immunity and performance of the totem pole output stage.
- What are some common applications of the UC3843ADR2?
Common applications include off-line converters, DC-to-DC converters, and switch mode power supplies.
