原标题：NEC μPD168804四路降压升压恒流驱动方案

　　NEC公司的 µPD168804是四路降压或升压恒流驱动器,每路的驱动电流可高达1500mA,升压或降压工作模式可通过外接元件来选择. 主要应用在加热器,低压工业照明, D背光照明等.本文介绍了µPD168804主要特性,方框图以及降压和升压应用电路图.

　　µPD168804:4 CH BUCK OR BOOST SELECTABLE CONSTANT CURRENT DRIVER IC WITH EXTERNAL POWER MOSFETS

　　The µPD168804 is a power supply control IC with four constant-current controller/driver channels. A high current drive of up to 1,500 mA per channel is supported by providing an external power MOSFET. Furthermore, operating conditions for either step-up or step-down operation can be selected and used according to the configuration of external components and settings of selected pins. The µPD168804 has separate circuits for protecting against overheating, low voltages, overcurrents, and overvoltages (step-up operation only), and can control load currents by externally inputting PWM signals.

　　µPD168804主要特性:

　　Flexible choice of Buck or Boost is available (one from Buck topology or Boost topology) by the arrangement of external Power MOSFET, Shottkey barrier diodes and other external components and MODE pin setting.

　　High output current 1500 mA MAX. per each channel (set by external current sense resistor)

　　Chopping frequency = 1 MHz MAX.

　　Wide input voltage range (Buck mode: VOUT < VIN, Boost mode: VOUT > VIN)

　　On/Off and dimming control for each channel using PWM

　　Thermal Protection function

　　Over current protection for each channels

　　Over voltage protection (Boost mode)

　　Low voltage Lock-out function (UVLO)

　　Stand-by (Enable) pin

　　Efficient software development and various control, combined with All Flush MCU of NEC Electronics Corp

　　µPD168804主要应用:

　　Heaters

　　Low voltage industrial lighting

　　LCD Back-up lighting

　　Illuminated signs

　　图1.µPD168804方框图:升压模式

　　图2.µPD168804方框图:降压模式