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 ?
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;
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 ?
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.
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 ?
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.
hi VisonZ_71:
3、if use inactive sensor connection to shield , how to Liquid Tolerance ?
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 ?
