| 摘要 |
PURPOSE:To form a product with one mask by employing an ion implanting method to switch pull-up, pull-down resistor option. CONSTITUTION:An ion implantation switching transistor switch, and a pull-up, pull-down resistor are provided. An output terminal is switched optionally to a Nch open drain or Nch open drain + pull-up. A polysilicon resistor 102 is provided to protect ths output of an output Nch transistor 104 and against an external electrostatic breakdown. A Nch transistor 108 is for switching pull-up option, and when it is ion implanted, it becomes a depletion transistor, and its gate is at GND level. Accordingly, the transistor always remains ON state in a range of the GND to VDD, and its terminal becomes a Nch open drain + pullup resistor terminal. Then, when it is not ion implanted, the transistor 108 becomes an enhancement type and is always turned OFF. Accordingly, this terminal becomes a Nch open drain output terminal. |
