74LV4060 Ver la hoja de datos (PDF) - Philips Electronics
Número de pieza
componentes Descripción
Fabricante
74LV4060 Datasheet PDF : 18 Pages
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Philips Semiconductors
14-stage binary ripple counter with oscillator
Product specification
74LV4060
ÎÎÎÎÎÎÎÎÎÎ MR (from logic)
105
fosc
(Hz)
104
11 RS
C2
R2
RTC
10
CTC
9
103
Rt
Ct
SV00732
Figure 3.
Example of an RC oscillator. Typical formula for oscillator frequency:
fOSC + 2.5
x
1
Rt
x
Ct
102
10
103
10–4
104
10–3
105 Rt (W)
106
10–2 Ct (mF) 10–1
SV00328
Figure 4.
RC oscillator frequency as a function of Rt and Ct at
VCC = 1.2 to 3.6 V; Tamb = 25°C.
Ct curve at Rt = 100 kW; R2 = 200 kW.
Rt curve at Ct = 1 nF; R2 = 2 x Rt.
TIMING COMPONENTS LIMITATIONS
The oscillator frequency is mainly determined by Rt . Ct, provided R2 2Rt and R2 . C2 % Rt . Ct. 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 ’ON’ resistance in
series with it, which typically is 280 W at VCC = 1.2 V, 130 W at VCC = 2.0 V and 100 W at VCC 3.0 V. The recommended values for these
components to maintain agreement with the typical oscillation formula are: Ct > 50pF, up to any practical value, 10 kW < Rt < 1 MW. In order to
avoid start-up problems, Rt > 1 kW.
1998 Jun 23
11
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