TC9402CPD datasheet(15/20 Pages) MICROCHIP

Part #	TC9402CPD

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

PDF	20 Pages

Scroll/Zoom	100%

Manufacturer	MICROCHIP [Microchip Technology]

Direct Link	http://www.microchip.com

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15 / 20 page

DS21483B-page 15

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:

POWER-ON OPERATION/RESET

VDD

1000pF

Threshold

Detector

Ω

FIN

VDD

100k

Ω

µF

FIN

VCC

VSS

CLRA

CD4538

TC9400

(a)

(b)

To TC9400

TC9402CPD Datasheet(PDF) 15 Page - Microchip Technology