Built-in hysteresis to avoid erroneous output reset release. The hysteresis is opposite to the threshold voltage; for overvoltage options the hysteresis is subtracted from the positive threshold (V_ITP), for undervoltage options hysteresis is added to the negative threshold (V_ITN).

Figure 8-4 Hysteresis (Overvoltage Active-Low)

Figure 8-6 Hysteresis (Undervoltage Active-High)

Figure 8-5 Hysteresis (Overvoltage Active-High)

Figure 8-7 Hysteresis (Undervoltage Active-Low)

Table 8-1 shows a sample of hysteresis and voltage options for the TPS37. For threshold voltages ranging from 2.7 V to 8 V, one option is to select a fixed hysteresis value ranging from 0.5 V to 2.5 V in increments of
0.5 V. Additionally, a second option can be selected where the hysteresis value is a percentage of the threshold voltage. The percentage of voltage hysteresis ranges from 2% to 13%.

Knowing the amount of hysteresis voltage, the release voltage for the undervoltage (UV) channel is
(V_ITN(UV) + V_HYS) and for the overvoltage (OV) channel is (V_ITP(OV) - V_HYS). For a visual understanding of the UV and OV release voltage, see SENSEx Undervoltage (UV) Timing Diagram and SENSEx Overvoltage (OV) Timing Diagram. The accuracy of the release voltage, or stated in the Section 7.5 as Hysteresis Accuracy is ±1.5%. Expanding what is shown in Table 8-1, below are a few voltage hysteresis examples that include the hysteresis accuracy:

Undervoltage (UV) Channel

V_ITN = 0.8 V

Voltage Hysteresis (V_HYS) = 5% = 40 mV

Hysteresis Accuracy = ±1.5% = 39.4 mV or 40.6 mV

Release Voltage = V_ITN + V_HYS = 839.4 mV to 840.6 mV

Overvoltage (OV) Channel

V_ITP = 8 V

Voltage Hysteresis (V_HYS) = 2 V

Hysteresis Accuracy = ±1.5% = 1.97 V or 2.03 V

Release Voltage = V_ITP - V_HYS = 5.97 V to 6.03 V