UPD4702C NEC [NEC], UPD4702C Datasheet - Page 5

• Manufacturer Part Number: UPD4702C
• Description: INCREMENTAL ENCODER 8-BIT UP/DOWN COUNTER CMOS INTEGRATED CIRCUITS
• Manufacturer: NEC [NEC]

2. OPERATING PRECAUTIONS
changes all the bits (such as 00
power supply line is sufficiently low. It is therefore recommended that a decoupling capacitor (of around 0.1 F)
be connected between V
in a miscount. Therefore, if this kind of pulse is to be input because of encoder bounds, etc., a filter should be inserted
in the A & B phase inputs.
count or DOWN count
As the PD4702 incorporates an 8-bit counter, a large transient current flows in the case of a count value which
Also, if a pulse shorter than the phase difference time t
If PW is at 70 ns or more, the count value remains the same before and after pulse input. (UP count
A Phase (or B Phase)
B Phase (or A Phase)
DD
UP count is implemented, and therefore the the result is no change in the count value.)
and V
H
SS
0FF
right next to the IC as shown in Fig. 3.
H
PD4702
or 7F
Fig. 4 A & B Phase Input Pulses
V
V
DD
Fig. 3 Decoupling Capacitor
SS
H
C
C : 0.1
080
ceramic capacitor, etc.
H
). This will cause misoperation unless the impedance of the
SAB
F tantalum electrolytic laminated
+5 V
(70 ns) is input to the A/ B phase inputs, this will result
If a pulse such that PW < 70 ns is input
in the A or B phase, there is a danger of
a miscount.
PW
PD4702
DOWN
5