The MMDT5212W is a bipolar transistor with pre-biased digital transistor in a SOT-323 package made by Diotec. It is a 50V device with a 100mA current rating. The device has two collector pins, one emitter pin and one base pin and is commonly used as a switch in applications such as optoelectronic units and encoders. It has excellent brightness characteristics, making it ideal for use as a digital logic control. The MMDT5212W is used in various devices such as smart cards, security systems and industrial automation.