The TLV40x1 comparators have two inputs: one external input (IN) and one internal input that is connected to the integrated voltage reference. The comparator rising threshold is trimmed to the reference voltage (V_IT+) while the falling threshold is trimmed to (V_IT-). Since the rising and falling thresholds are both trimmed and warranted in the Electrical Characteristics Table, the TLV40x1 is equally suited for undervoltage and overvoltage detection. The difference between (V_IT+) and (V_IT-) is referred to as the comparator hysteresis and is 20 mV for TLV40x1Ry and 54 mV for TLV4021S5x. The integrated hysteresis makes the TLV40x1 less sensitive to supply-rail noise and provides stable operation in noisy environments without having to add external positive feedback to create hysteresis.

The comparator input (IN) is able to swing 5.5 V above (V-) regardless of the device supply voltage. This includes the instance when no supply voltage is applied to the comparator (V_S = 0 V). As a result, the TLV40x1 is referred to as fault tolerant, meaning it maintains the same high input impedance when V_S is unpowered or ramping up. While not required in most cases, in order to reduce sensitivity to transients and layout parasitics for extremely noisy applications, place a 1 nF to 100 nF bypass capacitor at the comparator input.

For the TLV40x1Ry comparators, the input bias current is typically 10 pA for input voltages between (V-) and (V+) and the value typically doubles for every 10°C temperature increase. The comparator input is protected from voltages below (V-) by an internal diode connected to (V-). As the input voltage goes below (V-), the protection diode becomes forward biased and begins to conduct causing the input bias current to increase exponentially. A series resistor is recommended to limit the input current when sources have signal content that is less than (V-).

For the TLV4021S5x, the input bias current is limited by the internal resistor divider with typical impedance of 2M ohms.