HEF4521B_09 Datasheet, PDF (11/17 Pages) NXP Semiconductors – 24-stage frequency divider and oscillator

NXP Semiconductors
RTC
C
V_DD
RS
V_DD
V_DD1
A1
Y1
Y2
Q18
A2
HEF4521B
MR
V_SS
Q24
V_SS1
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Fig 8.
f ≈ -₂--_.--₃----_×-----_R--¹--_T---_C-----_×-----_C-- ; R_S ≥ 2R_TC , where:
f is in Hz, R is in Ω, and C is in F.
R_S + R_TC < ^V-----^I--^L-_I--⁽_L--^m-_I--^a---^x--⁾ , where:
V_IL(max) = maximum input voltage LOW; and
I_LI = input leakage current.
RC oscillator circuit
HEF4521B
24-stage frequency divider and oscillator
10²
f_osc
(1)
(kHz)
10
(2)
1
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10^−1
1
10
10^−1
1
10² R_TC (kΩ) ₁₀3
10 C (nF) 10²
V_DD = 10 V; The test circuit is shown in Figure 8.
(1) R_TC; C = 1 nF; R_S ≈ 2 R_TC.
(2) C; R_TC = 56 kΩ; R_S = 120 kΩ.
Fig 9. Oscillator frequency as a function of
R_TC and C
HEF4521B_5
Product data sheet
Rev. 05 — 5 November 2009
© NXP B.V. 2009. All rights reserved.
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