74HC4060 Datasheet, PDF (11/12 Pages) NXP Semiconductors – 14-stage binary ripple counter with oscillator

Philips Semiconductors
14-stage binary ripple counter with oscillator
Product specification
74HC/HCT4060
Fig.7
Test set-up for measuring forward
transconductance g_fs = di_o / dv_i at v_o is
constant (see also graph Fig.8);
MR = LOW.
14
handbookg, h_fsalfpage
(mA/V)
12
10
MBA333
max.
typ.
8
min.
6
4
Fig.8
2
0
1
2
3
4
5
6
VCC (V)
Typical forward transconductance g_fs as a
function of the supply voltage V_CC at
T_amb = 25 °C.
RC OSCILLATOR
Fig.9
RC oscillator frequency as a function of
R_t and C_t at V_CC = 2.0 to 6.0 V; T_amb = 25 °C.
C_t curve at R_t = 100 kΩ; R2 = 200 kΩ.
R_t curve at C_t = 1 nF; R2 = 2 × R_t.
Typical formula for oscillator frequency:
f_osc = _{2----.--5----×}-----1R-----_t--_×-----C----_t
Fig.10 Example of a RC oscillator.
TIMING COMPONENT LIMITATIONS
The oscillator frequency is mainly determined by R_tC_t, provided R2 ≈ 2R_t and R2C2 << R_tC_t. 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, C_t must be larger than the inherent stray
capacitance. R_t must be larger than the “ON” resistance in series with it, which typically is 280 Ω at V_CC = 2.0 V, 130 Ω at
V_CC = 4.5 V and 100 Ω at V_CC = 6.0 V.
The recommended values for these components to maintain agreement with the typical oscillation formula are:
C_t > 50 pF, up to any practical value,
10 kΩ < R_t < 1 MΩ.
In order to avoid start-up problems, R_t ≥ 1 kΩ.
December 1990
11