46.11.9 Peripheral Touch Controller (PTC) Characteristics

Table 46-36. PTC Acquisition Clock
Symbol Description Min Max Units
FPTC_ACQ PTC Acquisition Clock - 8 Mhz
Table 46-37. Sensor Load Capacitance (1)
Symbol Mode PTC channel Min PCB External (2) Max Sensor Load (3) Units
Cload Self-capacitance Y0 5 54 pF
Y1 -
Y2 - 50
Y3 5 54
Y4 5
Y5 -
Y6 5
Y7 5
Y8 5
Y9 5
Y10 - 45
Y11 5 54
Y12 5
Y13 -
Y14 -
Y15 5 50
Y16 5 54
Y17 5
Y18 5
Y19 5
Mutual-capacitance All - 31
Note:
  1. These values are based on characterization. They are not covered in test limits in production.
  2. Minimum external capacitance must be added on PCB design per PTC channel. Ensure that the PCB and sensor design add enough parasitic capacitance on each PTC channel, otherwise, an external capacitor must be added.
  3. Capacitance load, the PTC circuitry, can compensate for each channel.
Table 46-38. Analog Gain Settings (1) (2)
Symbol Setting Average
Gain GAIN_1 1.0
GAIN_2 2.0
GAIN_4 3.9
GAIN_8 8.1
Note:
  1. Analog Gain is a parameter of the QTouch Library. Refer to the QTouch Library Peripheral Touch Controller User Guide.
  2. These values are based on characterization. They are not covered in test limits in production.

Power Consumption

The values in the Power Consumption table below are measured values of power consumption under the following conditions:

Operating Conditions

  • VDD = 3.3V

Clocks

  • OSC16M divided to 4MHz used as main clock source
  • CPU is running on flash with 0 wait state, at 4MHz
  • PTC Acquisition Clock (FPTC_ACQ) at 4MHz
  • Voltage Regulator mode: LPEFF enabled

PTC Configuration

  • Mutual-capacitance mode
  • One touch channel

System Configuration

  • Standby sleep mode enabled
  • RTC running on OSCULP32K: used to define the PTC scan rate, through the event system
  • Drift Calibration disabled: no interrupts, PTC scans are performed in standby mode
  • Drift Calibration enabled: RTC interrupts (wakeup) the CPU to perform PTC scans. PTC drift calibration is performed every 1.5 sec.
Table 46-39. Power Consumption (1)
Symbol Parameters Drift Calibration PTC scan rate (msec) Oversamples Ta Typ. Max. Units
IDD Current Consumption Disabled 10 4 Max. 85°C Typ. 25°C 6.2 49.2 µA
16 12.7 58.1
50 4 2.3 43.7
16 3.7 45.5
100 4 1.7 43.2
16 2.4 43.9
200 4 1.4 42.8
16 1.8 43.2
Enabled 10 4 8.3 51.7
16 14.2 60.5
50 4 3.0 44.8
16 4.8 47.0
100 4 2.3 44.5
16 2.8 45.4
200 4 1.9 43.9
16 2.4 44.2
Note:
  1. These values are based on characterization. They are not covered in test limits in production.