TLV7021 datasheet(23/44 Pages) TI

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1 / 2 R 4

C1 I n2

A 2

(R IIR )

R + R IIR

TLV7011, TLV7021, TLV7012, TLV7022

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SLVSDM5F – SEPTEMBER 2017 – REVISED MARCH 2020

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Typical Applications (continued)

At this time the comparator output trips pulling down the output to the negative rail. The value of VAat this point is

calculated by Equation 8.

(8)

if R1 = R2 = R3, then VA2 = VCC/3

The C1 now discharges though the R4, and the voltage VCC decreases until it reaches VA2. At this point, the

output switches back to the starting state. The oscillation period equals to the time duration from for C1 from

2VCC/3 to VCC / 3 then back to 2VCC/3, which is given by R4C1 × ln 2 fro each trip. Therefore, the total time

duration is calculated as 2 R4C1 × ln 2. The oscillation frequency can be obtained by Equation 9:

(9)

8.2.3.3 Application Curve

Figure 41 shows the simulated results of tan oscillator using the following component values:

•

R1 = R2 = R3 = R4 = 100 kΩ

•

C1 = 100 pF, CL = 20 pF

•

V+ = 5 V, V– = GND

•

Cstray (not shown) from VA TO GND = 10 pF

Figure 41. Square-Wave Oscillator Output Waveform

TLV7021 Datasheet(PDF) 23 Page - Texas Instruments