LB1921
Truth Table
Source → Sink
F/R = low
IN1 IN2 IN3
1
OUT3 → OUT2
H
H
L
2
OUT3 → OUT1
H
L
L
3
OUT2 → OUT1
H
L
H
4
OUT2 → OUT3
L
L
H
5
OUT1 → OUT3
L
H
H
6
OUT1 → OUT2
L
H
L
Note: Input high refers to the state where IN+ > IN–.
R/R = high
IN1 IN2 IN3
L
L
H
L
H
H
L
H
L
H
H
L
H
L
L
H
L
H
The formula below gives the relationship between the oscillator frequency (fOSC) and the FG frequency (fFC).
fFC (servo) = fOSC/(ECL divisor (16) × number of counts)
= fOSC/8192
Crystal Oscillator External Circuit
External Circuit Constants (reference values)
Xtal (MHz)
C1 (pF)
C2 (pF)
R (kΩ)
3 to 4
39
82
0.82
4 to 5
39
82
1.0
5 to 7
39
47
1.5
7 to 10
39
27
2.0
Note: The crystal used must have a fundamental frequency fo impedance to
3fo impedance ratio of 1:5 or greater.
Equivalent Circuit Block Diagram
No. 5439-5/10