The UC3842BD1013TR from STMicroelectronics is a high-performance fixed-frequency current-mode PWM controller designed for offline and DC/DC switching power supplies. It integrates a precision oscillator, error amplifier, PWM comparator, current-sense comparator, undervoltage lockout circuitry and a high-current totem-pole output stage, minimizing the number of external components required for a power-converter design.
The UC3842B uses peak current-mode control with cycle-by-cycle current limiting and automatic feed-forward compensation. Its oscillator is programmed using an external RT/CT network, with current-mode operation supported up to 500kHz and oscillator operation guaranteed at 250kHz. With the datasheet test values of RT=10kΩ and CT=3.3nF, the oscillator frequency is typically 52kHz.
The UC3842B is optimized for higher-voltage startup in offline converters. Its UVLO startup threshold is typically 16V, with a specified UC384xB range of approximately 14.5V to 17.5V, while the minimum operating voltage after startup is typically 10V. Maximum startup current is only 0.5mA, and the maximum PWM duty cycle is typically 96%, with operation approaching 100%.
An internally trimmed 5V reference provides an accurate reference for the control circuitry. The current-sense comparator has a typical maximum input signal of 1V. A high-current totem-pole output stage is designed for direct N-channel MOSFET drive, with an absolute-maximum output-current rating of ±1A and typical rise and fall times of approximately 50ns.
The specific UC3842BD1013TR ordering option is supplied in an 8-pin SO-8 surface-mount package with tape-and-reel packaging. ST identifies the part as an Industrial-grade, Ecopack2/RoHS-compliant product and currently lists the UC3842B family as Active and in volume production.
Key Specifications:
- Brand: STMicroelectronics / ST
- Part Number: UC3842BD1013TR
- Family: UC3842B
- Product Type: Current-Mode PWM Controller
- Control Architecture: Peak Current Mode
- Applications: Offline and DC/DC Power Conversion
- Maximum Operating Frequency: 500kHz
- Typical Oscillator Frequency: 52kHz under specified RT/CT conditions
- Guaranteed Oscillator Operation: Up to 250kHz
- Maximum Duty Cycle: 96% Typ, up to 100%
- UVLO Start Threshold: 16V Typ
- UVLO Start Range: 14.5V to 17.5V
- Minimum Voltage After Turn-On: 10V Typ
- Startup Current: 0.5mA Max
- Operating Supply Current: 12mA Typ
- Reference Voltage: 5.0V Typ
- Current-Sense Gain: 3V/V Typ
- Maximum Current-Sense Input: 1V Typ
- Cycle-by-Cycle Current Limiting: Yes
- Automatic Feed-Forward Compensation: Yes
- Latching PWM: Yes
- Output Stage: Totem-Pole
- Absolute-Max Output Current: ±1A
- Output Rise Time: 50ns Typ
- Output Fall Time: 50ns Typ
- Low-Impedance Supply Rating: 30V Max
- Internal Zener Voltage: 36V Typ
- Absolute Junction Temperature Range: -40°C to +150°C
- UC384xB Electrical-Spec Ambient Range: 0°C to +70°C
- Package: SO-8
- Pin Count: 8
- Mounting Type: SMD / SMT
- Packaging: Tape & Reel
- Grade: Industrial
- RoHS Compliance: Ecopack2
- Product Status: Active.
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