SLVS905B December 2008 – July 2024 TLV431A-Q1 , TLV431B-Q1
PRODUCTION DATA
For the TLV431 to properly be used as a comparator, the logic output must be readable by the receiving logic device. This is accomplished by knowing the input high and low level threshold voltage levels, typically denoted by VIH & VIL.
As seen in Figure 8-3, TLV431's output low level voltage in open-loop/comparator mode is ~1 V, which is sufficient for some 3.3V supplied logic. However, would not work for 2.5V and 1.8V supplied logic. In order to accommodate this a resistive divider can be tied to the output to attenuate the output voltage to a voltage legible to the receiving low voltage logic device.
TLV431's output high voltage is approximately Vsup due to TLV431 being open-collector. If Vsup is much higher than the receiving logic's maximum input voltage tolerance, the output must be attenuated to accommodate the outgoing logic's reliability.
When using a resistive divider on the output, be sure to make the sum of the resistive divider (R1 & R2 in Figure 8-2) is much greater than Rsup to not interfere with TLV431's ability to pull close to Vsup when turning off.