The UC384xB family of control ICs provides the nec- essary features to implement off-line or DC to DC fixed frequency current mode control schemes with a minimal external parts count.
The document describes the UC384xB family of control ICs designed to implement off-line or DC to DC fixed frequency current mode control schemes with a minimal external parts count. Key features include a trimmed oscillator for precise duty cycle control, voltage lockout protection, a precision reference, and a high current totem pole output stage suitable for driving N-Channel MOSFETs.
The datasheet provides absolute maximum ratings, detailed electrical characteristics for both UC284XB and UC384XB variants, and pin function descriptions. It also includes various application circuits and graphs illustrating performance characteristics such as oscillator frequency vs. timing resistor, output dead-time, and error amplifier gain and phase.
| Oscillator Frequency | 250kHz guaranteed at 250kHz, operation to 500kHz |
|---|---|
| Output Current | ±1 A |
| Output Energy | 5 µJ |
| Power Dissipation (Minidip) | 1.25 W |
| Power Dissipation (SO8) | 800 mW |
| Storage Temperature Range | - 65 to 150 °C |
| Junction Operating Temperature | - 40 to 150 °C |
| Reference Output Voltage | 5.00 V |
| Maximum Duty Cycle (UC2842B/3B) | 100% |
| Maximum Duty Cycle (UC2844B/5B) | 85% |
| Supply Current (Operating) | 12 mA |
The oscillator frequency is guaranteed at 250kHz, with current mode operation possible up to 500kHz.
The output stage can source or sink peak currents up to 1A.
The UC2842B and UC2844B have UVLO thresholds of 16V (on) and 10V (off).
The UC2844B and UC2845B have a maximum duty cycle range of 4% to 85%.