SEOUL (Reuters) - Samsung Electronics Co said on Tuesday it will spend about $4 billion at its chip plant in Austin, Texas, to renovate an existing chip producing line and boost production of system chips, widely used in popular smartphones and tablets.

The investment comes on top of 2.25 trillion won ($1.98 billion) in spending that Samsung announced in June to build a new logic chip plant in South Korea, and the conversion of two memory chip lines into logic chip production earlier this year to meet growing demand from mobile gadget customers such as Apple. ($1 = 1135.5750 Korean won)

(Reporting by Miyoung Kim; Editing by Richard Pullin)