DRIVER LSI OF LED RECORDING HEAD

摘要

PURPOSE:To enable trimming of a resistor inside a driver LSI for reducing the area of a LED recording head, by forming a plurality of polysilicon resistors, a plurality of polysilicon fuses and, a plurality of pads at connecting points of the resistors and fuses, on a chip of the driver LSI. CONSTITUTION:Instead of a trimming resistor 35 exteriorly mounted on a ceramic substrate in a conventional arrangement, five polysilicon resistors 14-18 (resistance values R1-R5) and five polysilicon fuses 19-23 are arranged in parallel on the same LSI chip, with six pads 24-29 at respective connecting points between the resistors 14-18 and fuses 19-23. The resistance value of each polysilicon fuse is sufficiently smaller than that of the polysilicon resistor. The quantity of light of the LED chip having N LED elements 5 and 9 is measured so as to obtain a constant current value whereby the quantity of light of the LED chip is constant. If the constant current value is I=VR/R1, a pulse voltage is applied between the pads 24 and 25 of the resistor 14 to, for example, burn out the fuse 19, so that the value of a resistor connected to a MOS transistor 11 becomes equal to R1.