TC9402CPD View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

TC9402CPD

Voltage-to-Frequency/Frequency-to-Voltage Converters

Microchip Technology 

TC9400/9401/9402

8.0 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 appli-

cations, 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

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 8-1 (a) and (b)). Where

predictable power-on operation is critical, a more com-

plicated circuit, such as Figure 8-1 (b), may be

required.

FIGURE 8-1:

FIN

1kΩ

POWER-ON OPERATION/RESET

(a)

VDD

VDD

14

1000pF

11 Threshold

Detector

TC9400

100kΩ

1µF

16

3 VCC

CLRA

4A

(b)

5

2

B

R

CD4538

VSS

8

1

C

6

Q

FIN

To TC9400

© 2002 Microchip Technology Inc.

DS21483B-page 15

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