cancel
Showing results for 
Search instead for 
Did you mean: 

PSoC 4 MCU

New Contributor II

   when i read the AN85951 application note, this below question confuse me, for some use?when we use the capsense in FPC for smarthome device and the size is too small ,how can i refer the rules;

1、Hole size :The recommended value is 10mil, but on the FPC it can't design 10mil, so what should customer choose , and 10mil is for external diameter of hole size

and what about the internal diameter?

2、Liquid Tolerance with shield rules is : When the space of  is not enough , how should we use , if the ensor and the shield electrode is 1 mm is necessary?

     if  this below rules is ok ??

    ATwo-Layer PCB:

          >Top layer: Hatch fill with 7-mil trace and 45-mil grid (25 percent fill). Hatch fill should be connected to the driven-shield signal.
          >Bottom layer: Hatch fill with 7-mil trace and 70-mil grid (17 percent fill). Hatch fill should be connected to the driven shield signal

          >The recommended air gap between the sensor and the shield electrode is 1 mm

3、if use  inactive sensor connection to shield , how to Liquid Tolerance ?

pastedImage_6.png

4、For the power , how we use line width?

5、Sensor trace to  sensor trace width , sensor trace to signal , sensor to power,  signal to signal, if the sapce is not enough, should the 0.25mm is the necessray??if not what the recommended value?  tks;

0 Likes
Reply
1 Solution
Moderator
Moderator

1、Hole size :The recommended value is 10mil, but on the FPC it can't design 10mil, so what should customer choose , and 10mil is for external diameter of hole size and what about the internal diameter?

Answer: The hole size doesn't matter, follow general PFC hole size design rule is OK.

2、Liquid Tolerance with shield rules is : When the space of  is not enough , how should we use , if the sensor and the shield electrode is 1 mm is necessary?

Answer: This space can be decrease when layout space is not enough, depends on specific situation。

If this below rules is ok ??

A Two-Layer PCB:

>Top layer: Hatch fill with 7-mil trace and 45-mil grid (25 percent fill). Hatch fill should be connected to the driven-shield signal.
>Bottom layer: Hatch fill with 7-mil trace and 70-mil grid (17 percent fill). Hatch fill should be connected to the driven shield signal

>The recommended air gap between the sensor and the shield electrode is 1 mm

Answer: Depends on specific situation, above is just a common rule, if pcb layout space is limited, this rule is hard to implement without any change.

3、if use inactive sensor connection to shield , how to Liquid Tolerance ?

pastedImage_6.png

Answer: This can avoid GND plate around current sensor.

4、For the power , how we use line width?

Answer: Use general rule.

5、Sensor trace to  sensor trace width , sensor trace to signal , sensor to power,  signal to signal, if the sapce is not enough, should the 0.25mm is the necessray??if not what the recommended value? 

Answer: Minimum 3mil trace width and space is acceptable.

View solution in original post

0 Likes
Reply
3 Replies
Moderator
Moderator

1、Hole size :The recommended value is 10mil, but on the FPC it can't design 10mil, so what should customer choose , and 10mil is for external diameter of hole size and what about the internal diameter?

Answer: The hole size doesn't matter, follow general PFC hole size design rule is OK.

2、Liquid Tolerance with shield rules is : When the space of  is not enough , how should we use , if the sensor and the shield electrode is 1 mm is necessary?

Answer: This space can be decrease when layout space is not enough, depends on specific situation。

If this below rules is ok ??

A Two-Layer PCB:

>Top layer: Hatch fill with 7-mil trace and 45-mil grid (25 percent fill). Hatch fill should be connected to the driven-shield signal.
>Bottom layer: Hatch fill with 7-mil trace and 70-mil grid (17 percent fill). Hatch fill should be connected to the driven shield signal

>The recommended air gap between the sensor and the shield electrode is 1 mm

Answer: Depends on specific situation, above is just a common rule, if pcb layout space is limited, this rule is hard to implement without any change.

3、if use inactive sensor connection to shield , how to Liquid Tolerance ?

pastedImage_6.png

Answer: This can avoid GND plate around current sensor.

4、For the power , how we use line width?

Answer: Use general rule.

5、Sensor trace to  sensor trace width , sensor trace to signal , sensor to power,  signal to signal, if the sapce is not enough, should the 0.25mm is the necessray??if not what the recommended value? 

Answer: Minimum 3mil trace width and space is acceptable.

View solution in original post

0 Likes
Reply
New Contributor II

hi  VisonZ_71:

3、if use inactive sensor connection to shield , how to Liquid Tolerance ?

pastedImage_6.png

Answer: This can avoid GND plate around current sensor.

if  we just has one button to design Liquid Tolerance withe less space to put in shield , can this mode work ?

0 Likes
Reply
Moderator
Moderator

NO

0 Likes
Reply