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3.
When the resistor (R) is 1.3k, for example, the power capacity (W) of the resistor (R) becomes 0.638W.
2
W = (input voltage)
4.
Because the resistor requires a power capacity that is 3 to 5 times larger than the actual current consumption, the
resistor connected to the terminal should be 1.3k and 2 to 3W.
5.
The OFF voltage when the resistor (R) is connected becomes 2.15V. This satisfies that the OFF voltage of the DC input
circuit is 5V or lower.
1
1
1
+
1.3[kΩ]
1.6[kΩ]
An input signal does not turn off No.2
■Cause
By using two power supplies, a sneak path is configured.
E1
E2
E1 > E2
■Action
• Use one power supply.
• To prevent the sneak path, connect a diode as shown below.
E1
E2
22 TROUBLE EXAMPLES of DC INPUT/OUTPUT
446
22.1 Troubles and Countermeasures for DC Input Circuits
2
28.8
1300 = 0.638W
× 3[mA] = 2.15[V]
DC input
FPGA
module
DC input
FPGA
module
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Table of Contents
Troubleshooting
