Relaxation oscillator

AN4071

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Doc ID 022939 Rev 1

5

Relaxation oscillator

A relaxation oscillator belongs to the regenerative circuits group. One subgroup is

multivibrators which are furthermore classified as monostable, bistable and astable. The

relaxation oscillator is an astable multivibrator.

Figure 26.

Relaxation oscillator

The circuit in Figure 26 shows a representative circuit of relaxation oscillator based on the

TS3021 comparator. It uses both positive and negative feedback. Positive feedback

produces voltage hysteresis which has already been described in Section 4.2 Threshold

Considering zero voltage drop at the output see Equation 9:

Equation 9

1.

-t/

τ

-t/

τ

Equation 10

-t1/

τ

2/3

-1/3

1 = 2