Datasheet

CY8CMBR3002, CY8CMBR3102
CY8CMBR3106S, CY8CMBR3108
CY8CMBR3110, CY8CMBR3116 Datasheet
Document Number: 001-85330 Rev. *G Page 16 of 37
Note If more than one button is activated at the same time, the
Rn becomes equivalent (parallel) to all Rn resistors.
■ For the circuit represented in Figure 11 to work, GPOs should
be configured in the Active LOW logic, open-drain drive mode.
PWM must be disabled and the CSx-to-GPOx direct drive must
be enabled (that is, GPOs must be configured as
sensor-controlled).
■ The FSS feature can be enabled so only one button is reported
ON at a time.
System Diagnostics
System Diagnostics is a BIST feature that tests for faulty sensor,
shield, or CMOD conditions at device resets.
■ If any sensor fails these tests, a 50-ms pulse is sent out on the
corresponding GPO (that is, the pulse is observed on GPOx if
CSx fails the test), and the sensor is disabled.
■ If the shield fails the tests, a 50-ms pulse is sent out on all GPOs
and all the sensors are disabled.
■ If CMOD fails the tests, a 50-ms pulse is sent out on all GPOs
and all the sensors are disabled.
■ System Diagnostics failure pulses are sent within device
boot-up time.
■ The System Diagnostics status is also updated in the register
map. Therefore, the host can also read test results through the
I
2
C interface.
Sensor C
P
> 45 pF
If the parasitic capacitance of a sensor is more than 45 pF, the
sensor is disabled.
Improper value of CMOD
If the value of CMOD is less than 1 nF or greater than 4 nF, all
sensors are disabled (the recommended value of CMOD is
2.2 nF).
Sensor shorts
System Diagnostics also checks for the following errors:
■ Sensor shorted to V
ss
■ Sensor shorted to V
DD
■ Sensor shorted to another sensor
■ Sensor shorted to shield