User`s manual
28
3.1.1 The input waveform and the phase difference between phase
A pulse and phase B pulse
The count may be done incorrectly by inputting pulses whose phase difference is small between the phase A pulse
and phase B pulse in 2-phase input. The following figures show the pulse waveform to be input to the QD65PD2 and
the phase difference between the phase A pulse and phase B pulse in 2-phase input.
(Though the following are the cases for the differential input, they are also applied to the DC input.)
(1) Input waveform to the QD65PD2
Input pulse waveform should satisfy the condition shown below (the duty ratio is 50%).
(2) Phase difference in 2-phase input
Input pulse waveform in 2-phase input should satisfy the above condition (the condition required for 1-phase
input) and the conditions shown below.
Count
Subtraction count
Differential
voltage
H level
L level
t
0.1V -0.1V 0.1V
t
H tL
tH, tL 0.25 s (=0.5 t)
t (=tH+tL) 0.5 s
t
1,
t
2,
t
3,
t
4
0.125 s (=0.25 t)
Differential
voltage
H level
L level
Differential
voltage
H level
L level
Differential
voltage
H level
L level
Differential
voltage
H level
L level
0.1V -0.1V 0.1V
-0.1V 0.1V -0.1V
0.1V -0.1V 0.1V
t
1
t
2
t
3
t
4
0.1V -0.1V 0.1V
A
B
A
B