UC3842B Current Mode PWM

The UC284xB family of control ICs provides the necessary features to implement off-line or DC to DC fixed frequency current mode control schemes with a minimal external parts count. Internally implemented circuits include a trimmed oscillator for precise DUTY CYCLE CONTROL under voltage lockout featuring start-up current less than 0.5mA, a precision reference trimmed for accuracy at the error amp input, logic to insure latched operation, a PWM comparator which also provides current limit control, and a totem pole output stage designed to source or sink high peak current. The output stage, suitable for driving N-Channel MOSFETs, is low in the off-state.

Differences between members of this family are the under-voltage lockout thresholds and maximum duty cycle ranges. The UC2842B and UC2844B have UVLO thresholds of 16V (on) and 10V (off), ideally suited off-line applications The corresponding thresholds for the UC2843B and UC2845B are 8.5V and 7.9V. The UC2842B and UC2843B can operate to duty cycles approaching 100%. A range of the zero to < 50 % is obtained by the UC2844B and UC2845B by the addition of an internal toggle flip flop which blanks the output off every other clock cycle.

技术特性
  • TRIMMED OSCILLATOR FOR PRECISE FREQUENCY CONTROL
  • OSCILLATOR FREQUENCY GUARANTEED AT 250kHz
  • CURRENT MODE OPERATION TO 500kHz
  • AUTOMATIC FEED FORWARD COMPENSATION
  • LATCHING PWM FOR CYCLE-BY-CYCLE
  • CURRENT LIMITING
  • INTERNALLY TRIMMED REFERENCE WITH UNDERVOLTAGE LOCKOUT
  • HIGH CURRENT TOTEM POLE OUTPUT
  • UNDERVOLTAGE LOCKOUT WITH HYSTERESIS
  • LOW START-UP AND OPERATING CURRENT
功能框图
UC3842B 订购信息
订购型号 产品状态 美金价格 数量 封装 包装形式 温度范围 材料声明
UC3842BN Active 0.289 1000 DIP-8 Tube    
UC3842BD1013TR Active 0.289 1000 SO-8 Tape And Reel    
UC3842BD1 Active 0.289 1000 SO-8 Tube    
DATASHEET
描述 版本 大小
UC3842B : High performance current mode PWM controller 3 235KB