Peripheral Touch Controller (PTC) Characteristics

Table 1. PTC Acquisition Clock
Symbol	Description	Min	Max	Units
F_{PTC_ACQ}	PTC Acquisition Clock	-	8	Mhz

Table 2. 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	-	54
		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

Notes:

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 3. 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

Notes:

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 (F_{PTC_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 4. 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
			10	16		12.7	58.1
			50	4		2.3	43.7
			50	16		3.7	45.5
			100	4		1.7	43.2
			100	16		2.4	43.9
			200	4		1.4	42.8
			200	16		1.8	43.2
		Enabled	10	4		8.3	51.7
			10	16		14.2	60.5
			50	4		3.0	44.8
			50	16		4.8	47.0
			100	4		2.3	44.5
			100	16		2.8	45.4
			200	4		1.9	43.9
			200	16		2.4	44.2

Note:

1.These values are based on characterization. They are not covered in test limits in production.