US Patent 7728577 Automatic current trimming method and circuits

Techniques pertaining to device and method for controlling an analog signal are disclosed. Using a single connection (e.g., a connector or a pin) without an external resistive element (e.g., a resistor), an analog output is digitally controlled and produced. In one embodiment, a precisely controlled current is generated from coded data. A control unit is designed to control a working mode based on an input signal from the connection. The working mode includes a default mode, a programmable mode, a testing mode and a shutdown mode. Under the programmable mode, a user determines a signal coupled in from the connection as desired, and a code unit codes the signal in accordance with a predefined protocol. The code unit then sends the coded data to a decode unit. The decode unit is designed to generate or control the current by the decoded data.