TTP223 Erratic Behavior

[ThomsCircuit]

Ordered a breadboard adapter so i can test this and get it right.

...the touch sensor cap must be a low microphonic type like NP0?

can you explain what kind of capacitor this is?

 

[Tony Stewart]

View attachment 132226
Ordered a breadboard adapter so i can test this and get it right.


can you explain what kind of capacitor this is?

NP9/C0G ceramic caps are ultra-temp stable non-microphonic types with. A low dielectric constant so only in small values.

 

[ThomsCircuit]

NP9/C0G ceramic caps

ok this is for C5 #59
i was able to locate 20pf and 33pf in SMD and 20pf in a lead style.
I was hoping to find a range of values in lead and SMD but it is difficult. Thank you for clarifying. Ill do what i can to get whats needed.

 

[ThomsCircuit]

Ive read a lot about this TTP223 and how it works. That was after I did the following test. Now i realize how dumb this was. Im trying to use the IC in a manner that it was not designed for. The manufacture of the sunrom PCB that i acquired is listed as a demo product. It could be the reason why the schematic does not match the PCB. The good thing is i found out before i tried to implement this in my other project. Im going to rework the project so the touch pad is as close as possible to the IC. The parts will be in in a few days. i will test with the caps, resistors, and suggestions from the members of this group and post my results and any additional questions i will most likely have.

the test.
I connected one pair of a 24" length of this cat5 cable to pin3 of the ttp223 ic. The remaining pairs were left in the sheath.
I removed the SonRom pcb from the Swimming Pool project and placed it on a bread board.
Gave the IC 5.5volts and configured it for toggle / active high
I touched the tip of the wire and it worked. It also worked anywhere i touched the cable. infact it worked waving my hand near the wire. It was extremely sensitive. Not what i need for this project but it makes a pretty good proximity sensor.

 

[ThomsCircuit]

Why would this sch. ground pins 4-6 and the other connect them to VSS?
Pins 4 and 6 are configuration options for the ttp223 IC

 

[eTech]

Why would this sch. ground pins 4-6 and the other connect them to VSS?
Pins 4 and 6 are configuration options for the ttp223 IC

You stated VSS, but I think you mean VCC.
In these schematics, VCC=V+ VSS=Ground

Apparently, to set the option, you connect the pin to either V+ or ground.

 

[ThomsCircuit]

You stated VSS, but I think you mean VCC.

i did. thank you.
i also read that once you set the jumper(s) then apply power the IC holds the configuration even if you remove the jumpers

 

[eTech]

i also read that once you set the jumper(s) then apply power the IC holds the configuration even if you remove the jumpers

I don't think so. I didn't see that stated anywhere on the datasheet. At power on, it re-reads the configurations pins.
The device would require non-volatile memory to retain settings without the jumpers.

 

[ThomsCircuit]

I don't think so.

View this. The configuration segment is near the end

 

[eTech]

View this. The configuration segment is near the end

I'd go with the datasheet.


But if in doubt....test

 

[ThomsCircuit]

I finally got some time to put this together. for a novice im proud to say that this worked on the first try.
ive attached 2 additional breadboard views and the PCB. Its odd shape is designed to fit into a small project box. I designed the touch pad into a fabricated copper spring. that spring will be 1.5" when the larger plate compresses against it. The springs purpose is so the module can be eaisly serviced. On the pcb is also a bi-color led. it will be mounted in the plate. when the user touches the plate another circuit will change the leds color. The led will not be soldered on the board but inserted into a 3 pin female socket. The pcb also has two components on the opposite side for power and the leds signal from the other circuit.

The sensitivity adjustment range is 2.5-50pf. i selected 20pf and the response is perfect. no hovering trigger. only a light physical touch triggers the TTP223. I believe this layout best suits what this IC was designed for. im very pleased with how it turned. You have all taught me so much. I cant thank you enough.

 

[MacIntoshCZ]

To close to the pad

 

[ThomsCircuit]

To close to the pad

Can you explain? What is too close

 

[MacIntoshCZ]

Can you explain? What is too close

Track / net / red line.

 

[ThomsCircuit]

Track / net / red line

Ok. Got it. I can re-route pin 1 of the 223. Thank you

 

[MacIntoshCZ]

Ok. Got it. I can re-route pin 1 of the 223. Thank you

It might be enough for low voltage, but it could cause some troubles in production (image transfer to pcb/ etching). If there is a space, use it.

 

[ThomsCircuit]

track of pin 1 is 2.5mm from pad