TLV7021 datasheet(22/44 Pages) TI

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TLV7011, TLV7021, TLV7012, TLV7022

SLVSDM5F – SEPTEMBER 2017 – REVISED MARCH 2020

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Typical Applications (continued)

8.2.3 Square-Wave Oscillator

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

Figure 39. Square-Wave Oscillator

8.2.3.1 Design Requirements

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

8.2.3.2 Detailed Design Procedure

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

details of the steps.

Figure 40. Square-Wave Oscillator Timing Thresholds

First consider the output of Figure Figure 39 is 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.

(7)

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

TLV7021 Datasheet(PDF) 22 Page - Texas Instruments