upd4702 Renesas Electronics Corporation., upd4702 Datasheet - Page 5

• Manufacturer Part Number: upd4702
• Description: Incremental Encoder 8-bit Up/down Counter Cmos Integrated Circuits
• Manufacturer: Renesas Electronics Corporation.

2. OPERATING PRECAUTIONS
all the bits (such as 00H ↔ 0FFH or 7FH ↔ 080H). This will cause misoperation unless the impedance of the power supply
line is sufficiently low. It is therefore recommended that a decoupling capacitor (of around 0.1 µ F) be connected between
V
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.
or DOWN count → UP count is implemented, and therefore the the result is no change in the count value.)
DD
As the µ PD4702 incorporates an 8-bit counter, a large transient current flows in the case of a count value which changes
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 → DOWN count
and V
A Phase (or B Phase)
B Phase (or A Phase)
SS
right next to the IC as shown in Figure 2–1.
Figure 2–2. A & B Phase Input Pulses
Figure 2–1. Decoupling Capacitor
µ PD4702
V
V
DD
SS
Data Sheet S14940EJ3V0DS
C
C : 0.1 µ F tantalum electrolytic laminated
ceramic capacitor, etc.
SAB
+5 V
(70 ns) is input to the A/ B phase inputs, this will result in a
If a pulse such that PW < 70 ns is input
in the A or B phase, there is a danger of
a miscount.
PW
µ PD4702
5