The TL431LI-Q1 is a three-terminal adjustable shunt regulator, with specified thermal stability over applicable automotive, commercial, and military temperature ranges. The output voltage can be set to any value between Vref (approximately 2.495 V) and 36 V with two external resistors. The device has a typical output impedance of 0.3 Ω. Its active output circuitry provides a very sharp turn-on characteristic, making it an excellent replacement for Zener diodes in many applications, such as onboard regulation, adjustable power supplies, and switching power supplies. This device is a pin-to-pin alternative to the industry standard TL431-Q1 with optimized Iref and IIdev performance. The lower Iref and IIdev values of the TL431LI-Q1 enable designers to achieve higher system accuracy and lower leakage current. The TL432LI-Q1 has exactly the same functionality and electrical specifications as the TL431LI-Q1, but has a different pinout for the DBZ package. The TL431LI-Q1 is offered in two grades, with initial tolerances (at 25°C) of 0.5% and 1%, for the B and A grade, respectively. The TL431LI-Q1 is also available in two temperature grades: grade 1 (denoted by a ’Q’ in the part number), and grade 0 (denoted by a ’E’ in the part number), which represent maximum ambient operating temperatures of 125°C and 150°C respectively. The TL43xLI-Q1 is characterized for operation from –40°C to 125°C for grade 1, and –40°C to 150°C for grade 0, and its low output drift versus temperature ensures good stability over the entire temperature range.