TLV9032DDFR.A datasheet(33/85 Pages) TI2

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7.2.8 Zero Crossing Detector

100 NŸ

5 NŸ

VIN

20 0Ÿ

10 NŸ

100 NŸ

BAT54

VOUT

R1 = R2 = (R5 / 2)

Figure 7-17. Zero Crossing Detector

A voltage divider of R4 and R5 establishes a reference voltage V1 at the non-inverting input. By making the

series resistance of R1 and R2 equal to R5, the comparator switches when VIN = 0. Diode D1 makes sure that V3

clamps near ground. The voltage divider of R2 and R3 prevents V2 from going below ground. A small amount of

hysteresis is used to provide rapid output voltage transitions.

7.2.9 Pulse Slicer

A Pulse Slicer is a variation of the Zero Crossing Detector and is used to detect the zero crossings on an input

signal with a varying baseline level. This circuit works best with symmetrical waveforms. The RC network of R1

and C1 establishes an mean reference voltage VREF, which tracks the mean amplitude of the VIN signal. The

noninverting input is directly connected to VREF through R2. R2 and R3 are used to produce hysteresis to keep

transitions free of spurious toggles. The time constant is a tradeoff between long-term symmetry and response

time to changes in amplitude.

When the waveform is data, TI recommends that the data be encoded in NRZ (Non-Return to Zero) format

to maintain proper average baseline. Asymmetrical inputs can suffer from timing distortions caused by the

changing VREF average voltage.

10M

470 k

0.01 F

Output

VREF

VIN

Figure 7-18. Pulse Slicer Using TLV903x

For this design, follow these design requirements:

• The RC constant value (R2 and C1) must support the targeted data rate to maintain a valid tripping threshold.

• The hysteresis introduced with R2 and R43 helps to avoid spurious output toggles.

The TLV902x can also be used, but with the addition of a pull-up resistor on the output (not shown for clarity).

Figure 7-19 shows the results of a 9600 baud data signal riding on a varying baseline.

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SNOSDA3H – JUNE 2020 – REVISED NOVEMBER 2025

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TLV9032DDFR.A 数据表(PDF) 33 Page - Texas Instruments

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