Time (5 ms/div)

Output Voltage

Input Voltage

C030

TLV1701

TLV1702

TLV1704

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SBOS589 – DECEMBER 2013

APPLICATION INFORMATION

GENERAL DESCRIPTION

The TLV170x comparators features rail-to-rail input and output on supply voltages as high as 36 V. The rail-to-

rail input stage enables detection of signals close to the supply and ground. The open collector configuration

allows the device to be used in wired-OR configurations such as window comparator. A low supply current of 55

μA/channel with small, space-saving packages, makes these comparators versatile for use in a wide range of

applications, from portable to industrial.

COMPARATOR INPUTS

The TLV170x are rail-to-rail input comparators, with an input common-mode range that includes the supply rails.

The TLV170x is designed to prevent phase inversion when the input pins exceed the supply voltage. Figure 18

shows the TLV170x response when input voltages exceed the supply, resulting in no phase inversion.

Figure 18. No Phase Inversion: Comparator Response to Input Voltage (Propagation Delay Included)

CIRCUIT LAYOUT

Comparators are very sensitive to input noise. For best results, the following layout guidelines should be

maintained:

1. Use a printed circuit board (PCB) with a good, unbroken low-inductance ground plane. Proper grounding

(use of ground plane) will help maintain specified performance of the TLV170x.

2. To minimize supply noise, place a decoupling capacitor (0.1-

μF ceramic, surface-mount capacitor) as close

3. On the inputs and the output, keep lead lengths as short as possible to avoid unwanted parasitic feedback

around the comparator. Keep inputs away from the output.

4. Solder the device directly to the PCB rather than using a socket.

5. For slow-moving input signals, take care to prevent parasitic feedback. A small capacitor (1000 pF or less)

placed between the inputs can help eliminate oscillations in the transition region. This capacitor causes some

degradation to propagation delay when the impedance is low. The topside ground plane runs between the

output and inputs.

6. The ground pin ground trace runs under the device up to the bypass capacitor, shielding the inputs from the

outputs.

Copyright © 2013, Texas Instruments Incorporated

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