stmpe16m31px STMicroelectronics, stmpe16m31px Datasheet - Page 49

• Manufacturer Part Number: stmpe16m31px
• Description: S-touch? 16/24-channel Touchkey Controller With Proximity Sensing
• Manufacturer: STMicroelectronics

STMPE16M31PX, STMPE24M31PX
13.1
Figure 13. Touch sensing module flowchart
Sampling rate calculation
The capacitive sensor operates with a 2 MHz base clock, a single capacitive sensor scans
up to 24 active channels.
The SCLK_DIV divides the sensor clock by 32-1024, giving 2 kHz-67.5 kHz sensor clock.
For capacitive sensing, a PRBS sequence is utilized to remove the effect of surrounding
noise. This PRBS has an average value of 4.5.
The effective total sampling rate is thus 2 kHz-67.5 kHz divided by 4.5, giving 440 Hz –
14 kHz.
If all 24 channels of capacitive sensors are active, the channel conversion rate is thus
440 Hz/24 = 18.3 Hz (Min), 14 kHz/24 = 580 Hz (Max)
Using the maximum MAF setting (18 remove 2), the maximum filtered channel output rate is
580 Hz/18 = 32Hz.
Doc ID 17058 Rev 1
Touch sensor controller
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