Questions tagged [pulldown]
A pull-down resistor brings a line down to a voltage (typically ground potential) when the line isn't being driven to a specific voltage. It prevents the line from "floating" with an unknown voltage on it.
317 questions
3 votes
5 answers
642 views
Any reason the gate pull-down shouldn't be eliminated on an RP2040/RP2350 GPIO connection?
Regarding the practice of including a grounding resistor on the input of a MOSFET gate to prevent float conditions from biasing the MOSFET into the active region... Since the RP2040/RP2350 MCUs ...
- 139
1 vote
1 answer
88 views
Selecting biasing resistor values for MAX3485
I created a schematic for the MAX3485 with the ESP32, but I have a question about the selection of biasing resistor(R39,R40) values. Some people use 4.7k, 10k, and 20k ohm resistors, but I'm unsure ...
- 401
2 votes
6 answers
1k views
When would we like to use a resistor here?
In Xilinx's 7 Series FPGAs Configuration User Guide (UG470), they say M[2:0] determine the configuration mode. Connect each mode pin either directly, or via a ≤1 kΩ resistor, to VCCO_0 or GND. Adding ...
- 717
1 vote
2 answers
187 views
External resistor pull down values for STM32 gpio
While I play with STM32 a lot on the software side, I still miss a lot of hardware knowledge so I want to confirm my thinking before making a test PCB. I use STM32L4R5 GPIO to control LM3800 power ...
- 155
1 vote
1 answer
61 views
Sensor power sequencing
I am trying to make a power up sequence for a sensor that requires 3.3V, 5V and 10V. 5V and 10V power should be applied after 3.3V. My PCB is powered by 12V, and I use STM32L4R5, connected to the EN ...
- 155
1 vote
1 answer
128 views
Validating the connection of button to GPIO
I drew a schematic of connecting button to GPIO with input mode with built-in pull up / pull down resistor: Is it a true connection? if it's not, can you fix the problem? The thing I want to do is so ...
- 29
6 votes
3 answers
1k views
Relative Resistances of Pull-Up vs. Pull-Down Resistors
I’ve been reading the book “Complex Digital Hardware Design” by Istvan Nagy. On page 74 he writes PU [resistors are] typically 3 to 10 times larger resistor value than PD. On 3.3V signals a 10k PU ...
- 307
3 votes
4 answers
566 views
Pullup/down line depening on microcontroller
I am currently trying to design a circuit that makes it possible to either pull up a line to 5V or pull it down to ground depending on the signal of a microcontroller. The resistor needs to be 1K to ...
- 419
5 votes
4 answers
1k views
Pull-up and pull-down resistances technology in microcontrollers
I am making measurements for the characterization of pull-up and pull-down resistances in microcontrollers GPIO interface. I am currently working on a STM32 microcontroller, and in particular the ...
- 51
0 votes
0 answers
53 views
SN04-N2 NPN NC Inductive Proximity Sensor Status LED Pull-Up/-Down Resistor Value?
Both of my 'Cube-like' SN4-N2 Inductive Sensor (NPN NC) LED go slightly 'Dim' when activated. I need the LED to turn Off/On when activated. I've tried 5K6 and 2K7 resistors with little change in LED ...
1 vote
1 answer
245 views
How to estimate pull up/down resistors for the digital pins of this IC?
Regarding this power multiplexer IC's the digital inputs D0 and D1, the input impedance of the D0 and D1 is not given. Only Input current at D0 or D1 is given as 1.4uA. So far I ended with the ...
- 1,622
2 votes
1 answer
226 views
a4988 pulldown resistor necessary for ms1 ms2 ms3
Im using a4988 and are constructing a small pcb carrier for multiple a4988. I have a question on how to connect ms1, ms2, ms3. Do I need pulldown resistors after my DIP switch? Is it necessary? When I ...
- 213
1 vote
1 answer
117 views
Pull-up and pull-down resistors values
This is my first project: Do you think that all the pull-up and pull-dwn resistors value are good? Do the capacitor are oversized? Any suggestions about the circuit in general? Thank you :) Updates:
- 141
12 votes
5 answers
1k views
Pull up resistor question
Like many others I'm in software so apologies in advance if the question sounds dumb. I watched some videos, read some articles and also read some answers here, such as: Pull-up resistor clarification ...
- 135
2 votes
1 answer
46 views
VNQ9080 input pull-downs
I'm using the VNQ9080 in a design and am undecided about adding pull-downs to the inputs. The inputs are controlled from a SX1509 I2C I/O expander which has the pins on HI-Z by default. I want to make ...
- 25