STMicroelectronics UC3842BN Current Mode PWM Controller IC, DIP8

The STMicroelectronics UC3842BN is a high-performance current mode PWM (Pulse Width Modulation) controller integrated circuit designed for efficient and reliable power management. It provides all the necessary features to implement fixed-frequency current mode control schemes, suitable for both off-line and DC-to-DC converter applications, with a minimal external component count.

Internally, the IC incorporates a trimmed oscillator for precise duty cycle control and frequency stability. It features an under-voltage lockout (UVLO) circuit with a very low start-up current of less than 0.5mA, ensuring efficient initial operation. A precision voltage reference, trimmed for accuracy at the error amplifier input, enhances overall system stability. The design includes logic for latched operation and a PWM comparator that also provides current limit control, paired with a high-current totem pole output stage capable of sourcing or sinking significant peak current.

Key Features & Performance

• Precise Control: Trimmed oscillator guarantees a frequency of 250kHz for accurate timing and control.
• High-Speed Operation: Supports current mode operation up to 500kHz.
• Enhanced Stability: Automatic feed-forward compensation improves line regulation.
• Robust Protection: Latching PWM enables cycle-by-cycle current limiting for reliable overload protection.
• Reliable Start-up: Internally trimmed reference with under-voltage lockout and hysteresis ensures stable operation under varying input conditions.
• Strong Drive: High-current totem pole output for directly driving power MOSFETs.
• Low Power: Features low start-up and operating current for improved efficiency.

Technical Specifications

• Controller Type: Single Ended
• Channels: 1
• Control Mode: Current Mode
• Supply Voltage: 12V to 25V (Nominal 15V)<b