Tolerance and output current — the accuracy and drive limits
The TL431IDT is an adjustable shunt voltage reference from STMicroelectronics, part of the industry-standard TL431 family. Its key specifications include a ±2.21% tolerance on the internal 2.495 V reference, a 100 mA maximum output current, and a minimum cathode current of 1 mA. The output voltage is adjustable up to 36 V using two external resistors.
Where it fits — power supplies, chargers, and feedback loops
This shunt reference is used in switch-mode power supply feedback loops, linear regulators, battery chargers, and overvoltage protection circuits.
What the ±2.21% tolerance means for the BOM
The ±2.21% tolerance on the 2.495 V reference translates to a worst-case voltage deviation of about ±55 mV at the reference pin. For a 12 V output supply using a typical resistor divider, this adds roughly ±0.3% to the overall output tolerance. If the design requires tighter regulation, consider the TL431A or TL431B grades with ±1% or ±0.5% tolerance respectively.