Method for calibrating components permitting the use of low cost components

A method for calibrating components on a circuit board, said components including at least one digital to analog converter (DAC) and a corresponding resistor for each DAC, each resistor being connected to a corresponding output terminal, the circuit board interfacing with a test fixture having a precision test resistor, each output terminal being connected to the precision test resistor, the circuit board further including a controller for controlling the calibration method, the method comprising the steps of:

• a) loading a predetermined DAC with a load value corresponding to a predetermined current;
• b) reading a voltage value across the corresponding DAC resistor;
• c) calculating a resistor value for the resistor corresponding to the predetermined DAC;
• d) storing the resistor value calculated from step (c);
• and
• e) repeating the method at step (a) for a next DAC until all the DAC resistors have been calibrated, each resistor value having the same accuracy as the accuracy of the precision test resistor.

A method for calibrating components on a circuit board, said components including at least one digital to analog converter (DAC) and a corresponding resistor for each DAC, each resistor being connected to a corresponding output terminal, a precision value of each resistor being stored on the circuit board, the circuit board further having a test output terminal for completing the circuit to each DAC, the circuit board further including a controller for controlling the calibration method, the method comprising the steps of:

• a) connecting each output terminal to the test output terminal;
• b) loading a predetermined DAC with a first load value, the first load value initially corresponding to a nominal value of a first predetermined current;
• c) reading a voltage value across the corresponding resistor of the DAC;
• d) calculating a DAC current value being outputted from the DAC using the stored value of the corresponding resistor;
• e) if the DAC current value equals the first predetermined current,
• i) saving the first load value;
• otherwise
• ii) modifying the first load value and proceeding to step (a);
• f) when all the DACs have been processed to determined each corresponding first load value, which corresponds to a corresponding first predetermined count value for each respective DAC, repeating the method at step (a) utilizing a corresponding second load value to determine a corresponding second predetermined count value, thereby defining a line for each respective DAC such that for any value of DAC output current desired from a predetermined DAC a count value to be loaded into a predetermined DAC can be calculated for the preselected DAC, thus calibrating each DAC.