CC

2

3

A 2

1

2

3

V

(R IIR )

V

R + R IIR

(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 for each trip. Therefore, the total time

duration is calculated as 2 R4C1 × ln 2.

The oscillation frequency can be obtained by Equation 9:

f

1 / 2 R 4

C1 I n2

u

u

(9)

6.2.2.3 Application Curve

Figure 6-11 shows the simulated results of an oscillator using the following component values:

• R1 = R2 = R3 = R4 = 100kΩ

• C1 = 100pF, CL = 20pF

• V+ = 5V, V– = GND

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

Figure 6-11. Square-Wave Oscillator Output Waveform

6.2.3 Adjustable Pulse Width Generator

Figure 6-12 is a variation of the square wave oscillator (see Figure 6-9) that allows adjusting the pulse widths.

R4 and R5 provide separate charge and discharge paths for the capacitor C depending on the output state.

TLV1812-EP, TLV1822-EP

SNOSDJ3 – MAY 2024

www.ti.com

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