Current controlled open-drain output driver

A circuit for controlling an output driver driving an output terminal, comprising:

• a current control circuit having an output;
• a switching controller configured to receive said output from said current control circuit and output a switching signal;
• and
• a first plurality of switching devices coupled to said output terminal and configured to drive said output terminal in response to said switching signal and an output data signal;
• wherein said first plurality of switching devices are controlled by said switching signal;
• and
• wherein said current control circuit, said switching controller and said first plurality of switching devices are implemented on an integrated circuit chip.

A circuit for maintaining a steady output voltage for an open-drain output driver, comprising:

• a current control circuit configured to generate a digital control code, said current control circuit further comprising:
• a comparator configured to generate a comparison result;
• an up/down counter configured to generate an output based on said comparison result, wherein said output represents said digital control code;
• a first plurality of binary-weighted switching devices coupled in a parallel configuration, wherein the drain node voltage of said first plurality of binary-weighted switching devices is compared to a voltage reference by said comparator to generate said comparison result;
• and
• a bandgap reference current generator for providing a current source for said first plurality of binary-weighted switching devices;
• wherein said output of said up/down counter is coupled to said first plurality of binary-weighted switching devices;
• a second plurality of binary-weighted switching devices;
• and
• a switching controller configured to receive said digital control code and couple each bit of said digital code to one of said second plurality of binary-weighted switching devices.

A method for maintaining a steady output voltage for an open-drain output driver, said output driver including a bandgap reference current generator for providing a current source to a plurality of binary-weighted switching devices coupled in a parallel configuration, comprising the steps of:

• comparing the drain node voltage of said plurality of binary-weighted switching devices to a reference voltage to generate a comparison result;
• generating a digital code using said comparison result;
• and
• switching said plurality of binary-weighted switching devices using said digital code;
• wherein said steps are performed by components implemented on an integrated circuit chip.