HEF4060B データシートの表示（PDF） - Philips Electronics

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HEF4060B

14-stage ripple-carry binary counter/divider and oscillator

Philips Electronics 

Philips Semiconductors

14-stage ripple-carry binary counter/divider

and oscillator

Product specification

HEF4060B

MSI

Timing component limitations

The oscillator frequency is mainly determined by

RtCt, provided Rt << R2 and R2C2 << RtCt. The function

of R2 is to minimize the influence of the forward voltage

across the input protection diodes on the frequency. The

stray capacitance C2 should be kept as small as possible.

In consideration of accuracy, Ct must be larger than the

inherent stray capacitance. Rt must be larger than the

LOCMOS ‘ON’ resistance in series with it, which typically

is 500 Ω at VDD = 5 V, 300 Ω at VDD = 10 V and 200 Ω at

VDD = 15 V.

The recommended values for these components to

maintain agreement with the typical oscillation formula are:

Ct ≥ 100 pF, up to any practical value,

10 kΩ ≤ Rt ≤ 1 MΩ.

Typical crystal oscillator circuit

In Fig.5, R2 is the power limiting resistor. For starting and

maintaining oscillation a minimum transconductance is

necessary.

Fig.5 External component connection for crystal

oscillator.

Fig.6 Test set-up for measuring forward transconductance gfs = dio/dvi at vo is constant (see also graph Fig.7);

MR = LOW.

January 1995

6

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