8.3.1 Operating Voltage

The TLV349x comparators are specified for use on a single supply from 1.8 V to 5.5 V (or a dual supply from ±0.9 V to ±2.75 V) over a temperature range of −40°C to 125°C.

8.3.2 Input Overvoltage Protection

The device inputs are protected by electrostatic discharge (ESD) diodes that conduct if the input voltages exceed the power supplies by more than approximately 500 mV. Momentary voltages greater than 500 mV beyond the power supply can be tolerated if the input current is limited to 10 mA. This limiting is easily accomplished with a small input resistor in series with the input to the comparator.

8.3.3 Setting Reference Voltage

It is important to use a stable reference when setting the transition point for the TLV349x. The REF1004 provides a 1.25-V reference voltage with low drift and only 8 µA of quiescent current.

8.3.4 External Hysteresis

Comparator inputs have no noise immunity within the range of specified offset voltage (±15 mV). For noisy input signals, the comparator output typically displays multiple switching as input signals move through the switching threshold. The typical comparator threshold of the TLV349x is ±15 mV. To prevent multiple switching within the comparator threshold of the TLV349x, external hysteresis must be added by connecting a small amount of feedback to the positive input. Figure 17 shows a typical topology used to introduce hysteresis, described in Equation 1.

Equation 1.

V_HYST sets the value of the transition voltage required to switch the comparator output by increasing the threshold region, thereby reducing sensitivity to noise.

Figure 17. Adding Hysteresis to the TLV349x