A High-Voltage Current-Sensing Circuit for LED Driver IC

LED Driver IC를 위한 고전압 전류감지 회로 설계

  • Min, Jun-Sik (Dept. of Semiconductor Eng., Chungbuk National University) ;
  • No, Bo-Mi (Dept. of Semiconductor Eng., Chungbuk National University) ;
  • Kim, Yeo-Jin (Dept. of Semiconductor Eng., Chungbuk National University) ;
  • Kim, Yeong-Seuk (Dept. of Semiconductor Eng., Chungbuk National University)
  • 민준식 (충북대학교 반도체공학과) ;
  • 노보미 (충북대학교 반도체공학과) ;
  • 김의진 (충북대학교 반도체공학과) ;
  • 김영석 (충북대학교 반도체공학과)
  • Published : 2010.06.16

Abstract

A high voltage current sensing circuit for LED driver IC is designed and verfied by Cadence SPECTRE simulations. The current mirror pair, power and sensing MOSFETs with size ratio of K, is used in our on-chip current sensing circuit. Very low drain voltages of the current mirror pair should be matched to give accurate current sensing, so a folded-cascode opamp with a PMOS input pair is used in our design. A high voltage high side LDMOST switch is used between the current sensing circuit and power MOSFET to protect the current sensing circuit from the high output voltage. Simulation results using 0.35um BCD process show that current sensing is accurate with properly frequency compensated opamp.

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