As a result of a comparator’s high open loop gain, there is a small band of input differential voltage where the output can toggle back and forth between “logic high” and “logic low” states. This can cause design challenges for inputs with slow rise and fall times or systems with excessive noise. These challenges can be overcome by adding hysteresis to the comparator.

The TLV1H103-SEP has a LE/HYS pin that can be used to increase the internal hysteresis of the comparator. To change the internal hysteresis of the comparator, connect a single resistor as shown in the adjusting hysteresis figure between the LE/HYS pin and VEE. A curve of hysteresis versus resistance is provided below to provide guidance in setting the desired amount of hysteresis.

Figure 7-1 Adjustable Hysteresis using External Resistor

Figure 7-2 Adjustable Hysteresis using External Voltage

Figure 7-3 Hysteresis vs. R_HYS at V_CC = 5V

Figure 7-4 Hysteresis vs. V_HYS at V_CC = 5V

To provide adjustable hysteresis, an external 0.7V to 1.2V voltage, such as from a DAC, can be forced into the LE/HYST pin, as shown in Figure 7-2 and Figure 7-4. The LE/HYST pin can be internally modeled as a 40k resistor in series with a 1.25V source to VEE, so any driving circuitry must be able to sink up to 32uA. Note that the output goes into latch when LE/HYST is ≤ 400mV, or go into shutdown when ≥ 1.25V.