| 摘要 |
An integrated circuit with programmable output drive/program pins includes a plurality of output pads (30) which are each operable to interface with a separate and dedicated output driver (38). The output driver (38) is operable to drive an LED output device (14) in an operating mode. In a program mode, the driver (38) is disabled and a program buffer (40) enabled. At the same time, the LED output device (14) is disabled such that no impedance is presented to the output pad (30) due to operation of the LED output device (14). A programming resistor (18) is disposed between the pad (30) and one of three program reference voltages. A first program state is represented when the resistor (18) is tied to ground, a second program state is represented when the resistor (18) is tied to an open circuit and a third program state is represented when the resistor (18) is tied to a positive voltage. The program buffer (40) senses the presence of the resistor and what voltage it is tied to by either sinking current to the pad (30) or sourcing current therefrom. Therefore, the resistor (18) can be disposed on the pad (30) during operation and a power on reset or any type of external reset controlling a CPU (46) to initiate the program operation.
|
