A polycarbonate composition comprising the following components, relative to the total weight of the composition: A) 30 - 80 wt. % of a copolycarbonate comprising i) 24 - 70 mol% of an unit of formula wherein * indicates the position where formula is connected to the polymer chain, R 1 , each independently, is hydrogen or C 1 -C 4 alkyl, R 2 , each independently, is C 1 -C 4 alkyl, n is 0, 1, 2 or 3, and ii) 30 - 76 mol% of an unit of formula : Wherein * indicates the position where formula is connected to the polymer chain, R 3 , each independently, is H, linear or branched C 1 -C 10 alkyl, and R 4 , each independently, is linear or branched C 1 -C 10 alkyl, wherein the mol% is calculated based on the total mole number of units of formula and formula , B) 10 - 40 wt. % of a homopolycarbonate comprising an unit of formula as defined above, wherein the weight-average molecular weight of the homopolycarbonate is in the range of 24000 - 28000g/mol, measured as indicated in the specification, C) 8 - 25 wt. % of a phosphorous flame retardant, D) 0 -10 wt. % of an impact modifier, and E) 0 - 8 wt. % of a rubber-free vinyl copolymer, wherein the total amount of the impact modifier and the rubber-free vinyl copolymer is no more than 15 wt. %, and the content by weight of the unit of formula in the polycarbonate composition is no less than 24 wt. %. A) 30 - 80 wt. % of a copolycarbonate comprising i) 24 - 70 mol% of an unit of formula wherein * indicates the position where formula is connected to the polymer chain, R 1 , each independently, is hydrogen or C 1 -C 4 alkyl, R 2 , each independently, is C 1 -C 4 alkyl, n is 0, 1, 2 or 3, and ii) 30 - 76 mol% of an unit of formula : Wherein * indicates the position where formula is connected to the polymer chain, R 3 , each independently, is H, linear or branched C 1 -C 10 alkyl, and R 4 , each independently, is linear or branched C 1 -C 10 alkyl, wherein the mol% is calculated based on the total mole number of units of formula and formula , i) 24 - 70 mol% of an unit of formula wherein * indicates the position where formula is connected to the polymer chain, R 1 , each independently, is hydrogen or C 1 -C 4 alkyl, R 2 , each independently, is C 1 -C 4 alkyl, n is 0, 1, 2 or 3, and * indicates the position where formula is connected to the polymer chain, R 1 , each independently, is hydrogen or C 1 -C 4 alkyl, R 2 , each independently, is C 1 -C 4 alkyl, n is 0, 1, 2 or 3, and ii) 30 - 76 mol% of an unit of formula : Wherein * indicates the position where formula is connected to the polymer chain, R 3 , each independently, is H, linear or branched C 1 -C 10 alkyl, and R 4 , each independently, is linear or branched C 1 -C 10 alkyl, wherein the mol% is calculated based on the total mole number of units of formula and formula , * indicates the position where formula is connected to the polymer chain, R 3 , each independently, is H, linear or branched C 1 -C 10 alkyl, and R 4 , each independently, is linear or branched C 1 -C 10 alkyl, wherein the mol% is calculated based on the total mole number of units of formula and formula , B) 10 - 40 wt. % of a homopolycarbonate comprising an unit of formula as defined above, wherein the weight-average molecular weight of the homopolycarbonate is in the range of 24000 - 28000g/mol, measured as indicated in the specification, C) 8 - 25 wt. % of a phosphorous flame retardant, D) 0 -10 wt. % of an impact modifier, and E) 0 - 8 wt. % of a rubber-free vinyl copolymer, the total amount of the impact modifier and the rubber-free vinyl copolymer is no more than 15 wt. %, and the content by weight of the unit of formula in the polycarbonate composition is no less than 24 wt. %. <EOS>