LM13600M datasheet(16/24 Pages) NSC

16 / 24 page

Additional Applications (Continued)

The Schmitt Trigger of

Figure 22 uses the amplifier output

current into R to set the hysteresis of the comparator; thus

H = 2xRxIB. Varying IB will produce a Schmitt Trigger with

variable hysteresis.

Figure 23 shows a Tachometer or Frequency-to-Voltage con-

verter. Whenever A1 is toggled by a positive-going input, an

amount of charge equal to (V

H−VL)Ct is sourced into Cf and

t. This once-per-cycle charge is then balanced by the cur-

rent of V

O/Rt. The maximum fIN is limited by the amount of

time required to charge C

t from VL to VH with a current of IB,

where V

L and VH represent the maximum low and maximum

high output voltage swing of the LM13600. D1 is added to

provide a discharge path for C

t when A1 switches low.

The Peak Detector of

Figure 24 uses A2 to turn on A1 when-

ever V

IN becomes more positive than VO. A1 then charges

storage capacitor C to hold V

O equal to VINPK. One precau-

tion to observe when using this circuit: the Darlington transis-

tor used must be on the same side of the package as A2

since the A1 Darlington will be turned on and off with A1.

Pulling the output of A2 low through D1 serves to turn off A1

so that V

O remains constant.

DS007980-27

FIGURE 20. Multiplexer

DS007980-28

FIGURE 21. Phase Lock Loop

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