TC9402EJD Ver la hoja de datos (PDF) - TelCom Semiconductor Inc => Microchip

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Fabricante

TC9402EJD

VOLTAGE-TO-FREQUENCY/FREQUENCY-TO-VOLTAGE CONVERTERS

TelCom Semiconductor Inc => Microchip 

VOLTAGE-TO-FREQUENCY/

FREQUENCY-TO-VOLTAGE CONVERTERS

1

TC9400

TC9401

TC9402

F/V POWER-ON RESET

In F/V mode, the TC9400 output voltage will occasion-

ally be at its maximum value when power is first applied. This

condition remains until the first pulse is applied to fIN. In most

frequency-measurement applications this is not a problem,

because proper operation begins as soon as the frequency

input is applied.

In some cases, however, the TC9400 output must be

2 zero at power-on without a frequency input. In such cases,

a capacitor connected from pin 11 to VDD will usually be

sufficient to pulse the TC9400 and provide a power-on reset

(see Figure 11A). Where predictable power-on operation is

critical, a more complicated circuit, such as Figure 11B, may

be required.

VDD

3

14

1000pF

1kΩ

fIN

11 THRESHOLD

DETECTOR

(A)

TC9400

4

VDD

(B)

16

5

3 VCC

B

2

1

R

C

5

CLRA

100kΩ

1µF

4A

CD4538

VSS

8

6

Q

fIN

To TC 9400

6

Figure 11. Power-On Operation/Reset

7

TELCOM SEMICONDUCTOR, INC.

8

3-299

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