Timeline for Choosing the proper value for a pulldown resistor in a logic circuit
Current License: CC BY-SA 4.0
9 events
| when toggle format | what | by | license | comment | |
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| Mar 10, 2023 at 0:09 | vote | accept | Cheche Romo | ||
| Jul 21, 2020 at 2:45 | comment | added | Audioguru | The logic family was not told. It might be antique TTL that needs an input pull down resistor of less than 500 ohms. 250 ohms works well. | |
| Jul 20, 2020 at 21:26 | history | edited | user105652 | CC BY-SA 4.0 |
Italics, first line.
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| Jul 20, 2020 at 19:15 | history | edited | user105652 | CC BY-SA 4.0 |
Added 5.1V to diode
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| Jul 20, 2020 at 18:56 | history | edited | user105652 | CC BY-SA 4.0 |
Added schematic
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| Jul 20, 2020 at 18:36 | history | edited | user105652 | CC BY-SA 4.0 |
Added to 2nd paragraph.
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| Jul 20, 2020 at 18:33 | comment | added | user105652 | @ElliotAlderson That is why I recommended 10 K to start with. Normally it takes elevated temperatures to bring out such high leakage. I have measured gate voltage with a 10 Mohm DVM Fluke 87-5 and it was only millivolts of leakage. | |
| Jul 20, 2020 at 14:03 | comment | added | Elliot Alderson | While the input impedance of a logic gate is very high, the input impedance of a CMOS chip is much lower because of the ESD protection circuits. I think a common specification for CMOS chips is 1uA of leakage current, so using a 1megohm resistor would cause a voltage as high as 1V on the input....not good. | |
| Jul 20, 2020 at 6:24 | history | answered | user105652 | CC BY-SA 4.0 |