Overview
The UC3842BN, part of the UC384xB family, is a high-performance fixed frequency current mode controller produced by STMicroelectronics. This IC is designed to implement off-line or DC to DC fixed frequency current mode control schemes with a minimal number of external components. It 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 suitable for driving N-Channel MOSFETs.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Bias and Driver Voltages (VCC, VC) | 30 | V |
| 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) | 5.0 | μJ |
| Current Sense, Voltage Feedback, Vref and Rt/Ct Inputs (Vin) | −0.3 to +5.5 | V |
| Compensation Voltage (Vcomp) | −0.3 to +7.2 | V |
| Output Voltage Low State (VOL) | 0.1 to 1.1 | V |
| Output Voltage High State (VOH) | 12 to 13.5 | V |
| Startup Threshold (VCC) | 6.0 | V |
| Oscillator Frequency | Up to 500 kHz | kHz |
| Operating Temperature Range | −40 to +105 | °C |
Key Features
- Internally trimmed oscillator for precise frequency control.
- Temperature-compensated reference with undervoltage lockout.
- High gain error amplifier and current sensing comparator.
- High current totem pole output stage for driving N-Channel MOSFETs.
- Low start-up and operating current.
- Under-voltage lockout with hysteresis.
- Current limiting and cycle-by-cycle current limiting.
- Latching PWM for single pulse metering.
- Automatic feed forward compensation.
Applications
The UC3842BN is specifically designed for off-line and DC to DC converter applications, offering a cost-effective solution with minimal external components. It is suitable for various power supply designs, including medium power quasi-resonant ZVS (Zero Voltage Switching) flyback converters.
Q & A
- What is the primary function of the UC3842BN?
The UC3842BN is a high-performance fixed frequency current mode controller designed for off-line and DC to DC converter applications.
- What is the oscillator frequency range of the UC3842BN?
The oscillator frequency can be programmed up to 500 kHz.
- What are the key features of the UC3842BN's output stage?
The output stage is a high current totem pole output, suitable for driving N-Channel MOSFETs, and is low in the off-state.
- What protective features does the UC3842BN include?
It includes input and reference undervoltage lockouts with hysteresis, cycle-by-cycle current limiting, and a latch for single pulse metering.
- What is the operating temperature range of the UC3842BN?
The operating temperature range is from −40°C to +105°C.
- How is the oscillator frequency programmed in the UC3842BN?
The oscillator frequency is programmed by the values chosen for the timing components RT and CT.
- What type of converters is the UC3842BN suitable for?
It is suitable for off-line and DC to DC converters, including medium power quasi-resonant ZVS flyback converters.
- What is the startup current of the UC3842BN?
The startup current is less than 0.5 mA.
- Does the UC3842BN have automatic feed forward compensation?
Yes, it includes automatic feed forward compensation.
- What are the package options for the UC3842BN?
The UC3842BN is available in DIP-8 and SO-8 packages.
