Cypress CapSense CY8CMBR2044, Design Manual

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CapSense Schematic Design
AN66308 - CY8CMBR2044 CapSense® Design Guide, Doc. No. 001-66308 Rev. *F 19
Table 3-3. R
DELAY
Value for LED ON Time
R
DELAY
(Ω)
Approx. LED ON Time
(ms)
Grounded 0
120 20
200 40
280 60
… …
7960 1980
8040 2000
> 8040 2000
Pulled to V
DD
2000
Floating 2000
Place R
DELAY
between the Delay pin and ground. LED ON Time varies from device to device. It is ±12% accurate at
room temperature and ±18% accurate at a temperature range of -40 °C to +85 °C.
If a Button Auto Reset is triggered for CSx, LED ON Time is not applied on GPOx. LED ON Time is disabled if Toggle
ON/OFF is enabled.
LED ON Time applies only to one GPOx at a time, meaning the LED ON Time counter resets every time a CSx
transitions to a NO TOUCH state.
Figure 3-7 illustrates how LED ON Time operates: CS1 resets the LED ON Time
counter, causing GPO0 to turn OFF prematurely.
Figure 3-7. LED ON Timing Diagram for Multiple Buttons
CS0
GPO0
CS1
GPO1
Start LED ON Time
Counter
Restart LED ON
Time Counter
Reset LED ON
Time Counter
LED ON Time
System Diagnostics
A built-in Power-on Self Test (POST) mechanism performs some tests at power-on reset (POR), which can be useful
in production testing. If any button fails these tests, a 5 ms pulse is sent out on the corresponding GPO within 175 ms
after POR. The following tests are performed on all of the buttons: