TLV9022 datasheet(28/67 Pages) TI

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8.2.2 Square-Wave Oscillator

Square-wave oscillator can be used as low cost timing reference or system supervisory clock source. A push-

pull output (TLV903x) is recommended for best symmetry.

100 pF

100 kŸ

VCC

100 kŸ

OUT

100 kŸ

Figure 8-9. Square-Wave Oscillator

8.2.2.1 Design Requirements

The square-wave period is determined by the RC time constant of the capacitor C1 and resistor R4. The

maximum frequency is limited by propagation delay of the device and the capacitance load at the output.

The low input bias current allows a lower capacitor value and larger resistor value combination for a given

oscillator frequency, which may help to reduce BOM cost and board space. R4 must be over several kilo-ohms

to minimize loading the output.

8.2.2.2 Detailed Design Procedure

The oscillation frequency is determined by the resistor and capacitor values. The following calculation provides

details of the steps.

Figure 8-10. Square-Wave Oscillator Timing Thresholds

First consider the output of Figure Figure 8-9 as high, which indicates the inverted input VC is lower than the

noninverting input (VA). This causes the C1 to be charged through R4, and the voltage VC increases until it is

equal to the noninverting input. The value of VA at the point is calculated by Equation 7.

R I IR

(7)

if R1 = R2= R3, then VA1 = 2 VCC/ 3

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.

TLV9020, TLV9021, TLV9022, TLV9024, TLV9030, TLV9031, TLV9032, TLV9034

SNOSDA3F – JUNE 2020 – REVISED MARCH 2023

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TLV9022 Datasheet(PDF) 28 Page - Texas Instruments