ZHCSIA7 May 2018 DLPA4000
PRODUCTION DATA.
The illumination function includes all blocks needed to generate light for the DLP system. The device uses a control loop to accurately set the current through the LEDs (see Figure 4). Use IDAC[9:0] to set the intended LED current. The Illumination driver controls the LED anode voltage VLED and as a result a current flows through one of the LEDs. The voltage across the sense resistor (RLIM) measures the LED current. Based on the difference between the actual and intended current, the loop controls the output of the buck converter (VLED) higher or lower. Switches P, Q, and R control the LED which conducts the current. The Openloop feedback circuitry" confirms that the control loop can be closed for cases when there is no path via the LED (for instance, when ILED= 0 A).
These blocks comprise the illumination control loop.