NOVA electronics Inc. MCX514 -
170
-
170
-
5.4
Remarks of Logic Design
a.
About TEST1, 2 Pins
Make sure that TEST1, 2 (141, 142) pins are connected to GND. If set to Hi, it will not work correctly at all due to running the
internal test circuit.
b.
About Unused Input Pins
Make sure that unused input pin A is connected to GND or VDD. If the unused pin is open, the signal level of the pin will be
unstable and may cause malfunction. Input pin B can be open.
c.
About Unused Bi-directional Pins
Make sure that unused bi-directional pins (Bi-directional A, D, E) are connected to VDD or GND through high impedance (about
10k~ 100 kΩ). If these pins are directly connected to GND or VDD, the IC may be damaged by overcurrent in case of such as a
programming mistake causes the output state. Bi-directional pins B, C can be open.
d.
De-coupling Capacitor
Please connect VDD and GND with three or four De-
coupling capacitors (about 0.1μF).
e.
Ringing noise by Terminal Induction
Ringing noise may occurred by inductance and load capacity of the output pin. The user can add a capacitor (10-100pF) to pins
to reduce the noise.
f.
Reflection on Transfer Path
The load capacity for outputting types A, B, and bi-directional A~E is 20-50pf. So, the reflection will happen if the PCB wiring is
more than 60cm. Please shorten the PCB wiring length as shorter as you can.
g.
Example of Connection between MCX514 and 5V type IC
The input/output of MCX514 is 5V tolerant. But its output can connect with TTL level input only. It cannot connect with CMOS
level input.
10K
+5V
Input A, B
Output A
Output B
Bi-directional
A, B
TTL Level Bi-direction
TTL Level Input
TTL Level Input
CMOS Level or
TTL Level Output
MCX514
5V Type IC