34.13 PTC Characteristics

Table 34-42. Sensor Load Capacitance
Symbol Mode PTC channel Max Sensor Load (1) Units
CLOAD Self-capacitance Y0 15 pf
Y1 22
Y2 18
Y3 22
Y4
Y5
Y6
Y7
Y8
Y9
Y10
Y11
Y12
Y13
Y14
Y15
Mutual-capacitance All 29
Note:
  1. Capacitance load that the PTC circuitry can compensate for each channel.
Table 34-43. Analog Gain Settings (1,2)
Symbol Setting Average
Gain GAIN_1 1.0
GAIN_2 2.0
GAIN_4 3.8
GAIN_8 7.8
GAIN_16 12.8
GAIN_32 -
Note:
  1. Analog Gain is a parameter of the QTouch Library. Refer to the QTouch Library Peripheral Touch Controller User Guide.
  2. GAIN_16 and GAIN_32 settings are not recommended, otherwise the PTC measurements might get unstable.

Power Consumption

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

Operating Conditions:

VDD = 3.3V

Clocks:

OSC8M used as main clock source, running undivided at 8 MHz.

CPU is running on flash with 0 wait states, at 8 MHz.

PTC running at 4 MHz.

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 34-44. Power Consumption (1)
Symbol Parameters Drift Calibration PTC scan rate (msec) Oversamples Ta Typ. Max. Units
IDD (2) Current Consumption Disabled 10 4 Max. 125°C Typ. 25°C 67 487 µA
16 75 498
50 4 62 481
16 64 484
100 4 62 481
16 63 482
200 4 61 481
16 62 482
Enabled 10 4 71 495
16 79 507
50 4 64 485
16 65 489
100 4 63 485
16 64 487
200 4 62 484
16 63 484
Note:
  1. These values are based on characterization.
  2. On this table, the LDO Voltage Regulator is enabled in Standby mode (SYSCTRL.VREG.RUNSTDBY = 1).