Patent ID: 7834654

Claim:
An apparatus comprising: a first combined drive and termination circuit configured to operate with a first supply voltage, the first combined drive and termination circuit comprising: a variable impedance pull-up network; a variable impedance pull-down network ; at least one first control input for setting a configuration of the pull-up network; at least one second control input for setting a configuration of the pull-down network; the apparatus further comprising: first pre-drivers connected to the variable impedance pull-up network for configuring the pull-up network by sending a first control signal to the at least one first control input, the first pre-drivers being configured to operate with a second supply voltage higher than the first supply voltage; and second pre-drivers connected to the variable impedance pull-down network for configuring the pull-down network by sending a second control signal to the at least one second control input, the second pre-drivers being configured to operate with the second supply voltage; the apparatus having a termination mode of operation in which the variable impedance pull-up network is configured to have a pull-up network termination impedance and the variable impedance pull-down network is configured to have a pull-down network termination impedance, the pull-up network and the pull-down network in combination functioning as a split termination; the apparatus having a drive mode of operation in which: to drive a high output, the pull-up network is configured to generate a specific impedance when switched ON; to drive a low output, the pull-down network is configured to generate a specific impedance when switched ON.