4013bt is very sensitive !!!

[Sharagim]

Hi,
I want to use 4013bt for turn on and off a circuit (as you see in my schematic attached)
It is working ok but I see it is very sensitive . for example when I touch bt4013 by hand it make it on/off. Is it ok ?
Is there any way to make it be less sensitive ?

BR,

 

[jiripolivka]

A 4013 is a CMOS logic circuit, therefore its input is "very sensitive". To make it operate reliably, use pull-up resistors from input to +Vcc.

 

[crutschow]

All unused inputs in a CMOS circuits should terminated either to ground or to V+. Otherwise you will likely get erratic results.

There is no attached schematic.

 

[schmitt trigger]

The 4013 has some Set and Reset terminals that must be properly terminated for it to operate reliably.
If I remember properly, the should be tied to ground, but please check the datasheet.

 

[Sharagim]

Sorry I missed the attachment , now it is in first post.

 

[snail888]

yes,cmos logic chip has high input impedance,so unused pins should configure as a constant level,such as pull-up or pull-down by 100K.

 

[rogerynt]

If timing is not very critical then consider to add a small shunt capacitor at input for de-bouncing purpose.

 

[Sharagim]

Thanks for your replies.
I solved the problem by a 1uf capacitor , Now it is working very stable.
Now I see another problem .
I am using this circuit for control of lm2576 (on/off) for making whole circuit on or off. This circuit working on battery too and when it is in standby mode for example in one day it used about 10% of battery (two li-ion 2Amp). I think it is a high!?
Do you think is there any solution to prevent this ?

 

[schmitt trigger]

The circuit consumed 200 mAHr in 24 hrs? Or about 8.3 mA of a continuous draw?

The LM2576 indicates a WORST CASE standby current of 0.2 mA...so you clearly have a load somewhere draining the excess current.

But we can only guess....
Therefore, to properly assist you, a complete schematic with component values is required.


Edit: For instance, the 10k pullup on the output of the 4013 is not required. The 4013's output is a totem pole, not an open drain.
You could have other issues like this.

 

[Sharagim]

Thx for reply.
Schematic attached.
I removed that 10k but nothing special happened yet (maybe I need more time to have a good estimation!).

 

[schmitt trigger]

Hmmmmmmmm, That is weird.

Do you have access to a multimeter?
Such that you can measure the supply current while in the "off" state?

 

[Sharagim]

I check it with multimeter.
I see 168mA when it is on and 15mA when it is in off stat!

 

[schmitt trigger]

Without being there to help you personally, you will have to check a couple of things;

1) That the LM2576 is turning off fully.

2) That there are no other components or connection in addition to what you are showing in your schematic.

3) That the flip-flop is not oscillating.

 

[Sharagim]

Thanks for reply.
After rechecking your comments I found out the problem.
I have a circuit for checking the input voltage with a voltage divider .
Input is about 8 v and I used a 4.7K and 1K to make it readable by ADC.
For instance I think changing the values to something like M will help (i am not sure yet) !!!
it is my pleasure to have your comment on this.

- - - Updated - - -

Now I see another problem when increase the value.
I see the output voltage of divider when is connected to ADC port is something different wrong for example unconnected show 1.3v but when I connect it to port I see 2.9v

 

[schmitt trigger]

I ignore which microcontroller you are using, but generally it is a good idea that the Thevenin equivalent of your resistor divider to be equal or less than 10k.
Higher values may cause errors.

For an 8V input, a voltage divider consisting of a pair of 20k would provide 4 volts and satisfy the requirement.

Having said that.... 4.7k and 1k across 8 Volt DO NOT consume 18 mA. You still have got SOMETHING ELSE connected.


Edit: "I see the output voltage of divider when is connected to ADC port is something different wrong for example unconnected show 1.3v but when I connect it to port I see 2.9v"
Are you sure the port is configured as an analog port and not something else?

 

[bking]

Without being there to help you personally, you will have to check a couple of things;

3) That the flip-flop is not oscillating.

There are two flip-flops in a 4013 package. Do you have the unsed inputs for the other half tied to GND or Vcc?
You don't need a pull-up on the output.

 

[Sharagim]

I am using Xmega and you are right something was wrong here , unfortunately I forget to disable JTAG so that pin was working wrong.
After I did it now I see current in offline mode is going to something like half.
I think this 7-8 mA is for 4013 (not sure)
bking: I removed that resistor by an advise before and unused pins are connected to GND.