ViewSonic VG150B Service Manual - Page 23

Service Manual VG150 THEORY OF CIRCUIT OPERATION ViewSonic April 1999 - Version 1.0 Symbol W Fog Factor 8 Vertical Minimum 11 input lines Maximum 11 Input pixels Source 3 HSIZE[11:8] Source 3 HSIZE[11:8] Source 8 HSIZE[7:0] Source 8 VSIZE[7:0] Check sum 8 640 640 720 640 800 1024 Description x x x x x x 350 400 400 480 600 768 17H 37H 57H 77H 97H B7H Vertical fogging factor 18H 38H 58H 78H 98H B8H Minimum input lines =(VSIZE + VBP)*Line Expansion When the input has fewer lines than this value, it is considered as an ERROR, and INPUT_X status bit will be HIGH. 1AH 3AH 5AH 7AH 9AH BAH Maximum input pixels per line. 1BH 3BH 5BH 7BH 9BH BBH Auto clock recovery will not set input PLL divisor larger than this value. 1CH 3CH 5CH 7CH 9CH BCH Source horizontal size upper 3 bits [6:4] [6:4] [6:4] [6:4] [6:4] [6:4] 1CH 3CH 5CH 7CH 9CH BCH Source vertical size upper 3 bits [2:0] [2:0] [2:0] [2:0] [2:0] [2:0] 1DH 3DH 5DH 7DH 9DH BDH Source horizontal size lower 8 bits lEH 3EH 5EH 7EH 9EH BEH Source vertical size lower 8 bits 1FH 3FH 5FH 7FH 9FH BFH Sum of above 31 bytes(keep lower 8 bits only) Input Mode Detection Data Symbol 7 Width (bits) 8 Data high threshold 8 Edge threshold 8 Address 120H 121H 122H Description Low water mark for valid data If the data is smaller than this threshold, it is considered LOW internally High water mark for valid data If data is larger than this threshold, it is considered HIGH internally Minimum difference between the data value of two adjacent pixels to be considered as an edge Page 20