Output Current Built-In Self-Test Scheme in Automotive High Density uLED Matrix Driver

A new era of automotive headlights has been enabled by recent high density (HD) and fully integrated pixelated light sources, which allow for the implementation of advanced lighting features such as anti-glare high beam systems, adaptive driving beam, and symbol projection. To fit the carmakers requirements in terms of light intensity, contrast and brightness, new HD light sources use uLED technology and integrate a LED driver IC that can control thousands of uLEDs individually using pulse-width modulation (PWM) control. For this purpose, each uLED is bonded on top of each output driver providing the required output current. To test each output current without a dramatic increase of the testing time, an integrated Built-In Self-Test (BIST) is a required solution. This paper proposes a BIST method designed to evaluate all the output currents in a fully integrated uLED matrix driver. Experimental findings demonstrate a strong correlation between BIST results and analog measurements, resulting in a reduction of the total test time by 64% with a negligible area overhead.