TLV1702-Q1, TLV1704-Q1

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SLOS890A – NOVEMBER 2015 – REVISED DECEMBER 2015

Typical Application (continued)

9.2.2 Detailed Design Procedure

Make a small change to the comparator circuit to add hysteresis. Hysteresis uses two different threshold voltages

to avoid the multiple transitions introduced in the previous circuit. The input signal must exceed the upper

threshold (VH) to transition low, or below the lower threshold (VL) to transition high.

Figure 20 illustrates hysteresis on a comparator. Resistor Rh sets the hysteresis level. An open-collector output

stage requires a pullup resistor (Rp). The pullup resistor creates a voltage divider at the comparator output that

introduces an error when the output is at logic high. This error can be minimized if Rh > 100 Rp.

When the output is at a logic high (5 V), Rh is in parallel with Rx (ignoring Rp). This configuration drives more

current into Ry, and raises the threshold voltage (VH) to 2.7 V. The input signal must drive above VH = 2.7 V to

cause the output to transition to logic low (0 V).

When the output is at logic low (0 V), Rh is in parallel with Ry. This configuration reduces the current into Ry, and

reduces the threshold voltage to 2.3 V. The input signal must drive below VL = 2.3 V to cause the output to

transition to logic high (5 V).

For more details on this design and other alternative devices that can be used in place of the TLV1702, refer to

Precision Design TIPD144, Comparator with Hysteresis Reference Design.

9.2.3 Application Curve

Figure 21 shows the upper and lower thresholds for hysteresis. The upper threshold is 2.76 V and the lower

threshold is 2.34 V, both of which are close to the design target.

Figure 21. TLV1701 Upper and Lower Threshold with Hysteresis

10 Power Supply Recommendations

The TLV170x-Q1 device is specified for operation from 2.2 V to 36 V (±1.1 to ±18 V); many specifications apply

from –40°C to +125°C. Parameters that can exhibit significant variance with regard to operating voltage or

temperature are presented in the Typical Characteristics section.

CAUTION

Supply voltages larger than 40 V can permanently damage the device; see the

Absolute Maximum Ratings.

Place 0.1-

μF bypass capacitors close to the power-supply pins to reduce errors coupling in from noisy or high-

impedance power supplies. For more detailed information on bypass capacitor placement; see the Layout

Guidelines section.

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