The STM8T141 is a ProxSense™ single-channel, fully integrated, charge-transfer, capacitive sensor that is designed to replace conventional electromechanical switches in cost-sensitive applications.

The STM8T141 is offered in 8-pin packages and is ideally suited for 1-button applications. It can be configured either in touch or proximity sensing mode for wake-up or backlighting on actuation.

The extremely low current consumption makes it an ideal solution for battery-powered applications.

The device features an internal voltage regulator to enhance detection sensitivity and stability.

The STM8T141 touchpad can sense through almost any dielectric and can thereby contain the electronics in a sealed environment.

The STM8T141 also incorporates the advantages of using a driven shielding capability. This makes it possible to separate the sealed electronics from the sensing electrode. The shield feature enables the designer to protect part of the sensing element from unwanted environmental interference and enhances proximity detection when used with battery (DC) applications.

ProxSense™ is a trademark of Azoteq.

Doc ID 15699 Rev 7 7/50

Block diagram STM8T141

Figure 1.

STM8T141 block diagram

ProxSense engine

Volt a ge reg u l a tor

POR

VREG

VDD

500 kHz RC o s cill a tor

MCU s y s tem engine TOUT/POUT

S HLDIN

8/50

S HLDOUT a i17207

RC oscillator

The 500-kHz RC oscillator is an internal fixed frequency oscillator used to supply the clock to the MCU system engine.

Power-On-Reset (POR)

The POR generates a reset signal depending on the power supply level and the clock pulses received from the RC oscillator.

Voltage regulator

The voltage regulator has an internal comparison and feedback circuit that ensures the

REG

voltage is kept stable and constant. The regulator requires an external smoothing capacitor.

MCU system engine

The MCU system engine controls the capacitive sensing engine and processes touch and proximity detection signals.

ProxSense engine

The ProxSense engine circuitry employs a charge-transfer method to detect changes in capacitance.

Doc ID 15699 Rev 7

STM8T141 Pin descriptions

Figure 2.

S08 pinout

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Figure 3.

UFDFPN8 pinout

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Table 2.

Pin no.

STM8T141 pin descriptions

PIn type

(1)

Pin name

SO8 UFDFPN8

Pin function

SNS

SHLDIN

(3)

Ground

Capacitive sensing channel pin to

(2)

Capacitive sensing channel pin to R

Shield input

Internal voltage regulator output

(4)

REG

SHLDOUT Shield output

TOUT/POUT

Supply voltage

Touch/proximity

(5)

output



(active high)

I: input pin, OD: open drain, PP: output push-pull pin, S: supply pin and SNS: capacitive sensing pin.

Use COG or NPO capacitor type.

If the active shield is unused, please connect this pin to V

Requires a low ESR, 1µF capacitor to ground. This output must not be used to power other devices.

Depending on the value of bits [1:0] of OPT0.

Doc ID 15699 Rev 7 9/50

STM8T ProxSense technology STM8T141

4.1 Capacitive sensing overview

A capacitance exists between any reference point and ground as long as they are electrically isolated. If this reference point is a sensing electrode, it can help to think of it as a capacitor. The positive electrode of the capacitor is the sensing electrode, and the negative electrode is formed by the surrounding area (virtual ground reference in

Figure 4 ).

Figure 4.

Coupling with hand increases the capacitance of the sensing electrode

Sensing electrode

4.2

Lower capacitance Higher capacitance

When a conductive object is brought into proximity of the sensing electrode, coupling appears between them, and the capacitance of the sensing electrode relative to ground increases. For example, a human hand raises the capacitance of the sensing electrode as it approaches it. Touching the dielectric panel that protects the electrode increases its capacitance significantly.

Charge transfer acquisition principle

To measure changes in the electrode capacitance, STM8T devices employ bursts of chargetransfer cycles.

The measuring circuitry is connected to the C

pin. It is composed of a serial resistor R

X plus the sensing electrode itself of equivalent capacitance C

(see

Figure 5 ). The sensing

electrode can be made of any electrically conductive material, such as copper on PCBs, or transparent conductive material like Indium Tin Oxide (ITO) deposited on glass or Plexiglas.

The dielectric panel usually provides a high degree of isolation to prevent ESD discharge from reaching the STM8T touch sensing controller. Connecting the serial resistor (R

) to the

pin improves ESD immunity even more.

10/50 Doc ID 15699 Rev 7

STM8T141

Figure 5.

STM8T measuring circuitry

STM8T ProxSense technology

S TM 8 T141

S eri a l re s i s tor (R

)(1)

E a rth

(~5 pF)

Cx (~20 pF)

( a few nF)

must be placed as close as possible to the STM8T device.

The principle of charge transfer is to charge the electrode capacitance (C

) using a stable power supply. When C

X is fully charged, part of the accumulated charge is transferred from

to an external sampling capacitance, referred to as C

The transfer cycle is repeated until the voltage across the sampling capacitor C

reaches the end of acquisition reference voltage (V

TRIP

). The change in the electrode capacitance is detected by measuring the number of transfer cycles composing a burst (see

Figure 6

●

Throughout this document the following naming conventions apply:

● The charge transfer period ( t

TRANSFER

) refers to the charging of C subsequent transfer of the charge to C

The burst cycle duration (t

BURST

) is the time required to charge C

S to V

TRIP

The sampling period (t

SAMPLING

) is the acquisition rate.

X and the

Figure 6.

Conversion period examples

Ai15249 a

42!.3&%2

T3!-0,).'

62%'

T"5234

642)0

Doc ID 15699 Rev 7 11/50

STM8T processing STM8T141

5.1

●

The STM8T141 device is designed to ensure reliable operation whatever the environment and operating conditions. To achieve this high level of robustness, dedicated processing have been implemented:

Signal and reference calculation

Determining touch/proximity

Self-calibration

Environmental compensation filter

Debounce filter

Signal and reference calculation

Capacitive touch or proximity sensing is a technique based on detecting the electrode capacitance change when someone is in proximity of the sensing electrode. The capacitance change, induced by the presence of a finger or a hand in the device detection area, is sensed by the variation in the number of charge transfer pulses composing the burst. The charge transfer pulse number, also called “signal” is compared to a reference to decide if there is a touch/proximity detection or not.

At power-up, a calibration sequence is performed to compute one reference value per capacitive sensing channel. The reference is extracted from 32 burst measurements. Then, the ECF takes care of its slow evolution over time.

To speed up the calibration process, the device is kept in normal mode whatever the low power mode selected. The device operates in the selected low power mode when the calibration process is completed.

The minimum difference between the reference and the signal necessary to report a touch/proximity is the detection threshold (D

). A time filtering, similar to the debouncing of the mechanical switches, is applied to avoid noise induced detections.

Four different detection threshold settings are available and selectable by option byte. The touch and sensitive touch levels are relative, which means the actual sensing distance is not influenced by the Cs capacitor. The two thresholds should be able to adapt to various surroundings and panel material or thickness. The proximity sensitivity thresholds are absolute. This implies that the detection distance increases with the Cs capacitor. It provides an easy way to tune the proximity sensing distance according to the application needs.

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STM8T141

5.3 Environment compensation filter (ECF)

STM8T processing

The capacitive sensing channel reference value increases or decreases according to environmental conditions such as temperature, power supply, moisture, and surrounding conductive objects. The STM8T141 includes a built-in digital infinite impulse response (IIR) filter capable of tracking slow changes in the environment called the Environment

Compensation Filter (ECF). This is a first order digital low pass filter with a gain of one. The filter makes the reference follow slow changes of the signal while fast changes are recognized as a touch or proximity.

When a touch or proximity condition is detected, the corresponding capacitive sensing channel reference is frozen.

Figure 7.

Environmental compensation filter (ECF) example 1

.UMBEROFCOUNTS

2EFERENCE

3IGNAL

2EFERENCE$4H

$ETECTION

:ONE :ONE :ONE :ONE :ONE

Table 3.

Detection state

ECF operation

Reference

Explanation of ECF example 1

Zone 1 Zone 2

Event description

Zone 3 Zone 4

The object (finger) is outside the electrode field range.

Electrode environment is stable

The object, is inside the electrode field range. It induces a signal change but, not large enough to cross the detection threshold (Dth).

The reference adapts slowly to the object proximity.

The object comes inside the detection range before the reference compensates for its presence.

A touch or proximity event is triggered because the signal level falls below the reference - D

The object exits from the electrode’s detection range.

No detection

Active

Adapting

Detection

Halt

Frozen

No detection

Active

Adapting

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14/50

STM8T processing

Figure 8.

Environmental compensation filter (ECF) example 2

N u m b er of co u nt s

Reference

S ign a l

Reference - DTh

Detection

STM8T141

Environment ch a nging

Zone 1 Zone 2 Zone 3 Zone 4 t a i17429

Table 4.

Explanation of ECF example 2

Zone 1

Event description

Detection operation

ECF state

Reference

Surrounding environment

Zone 2 Zone 3

The system environment changes and the device adapts its reference according to this environment change.

An object (finger) is detected. The environment continues to change.

The object is still under detection but, the environment is not changing anymore.

No detection

Active

Adapting

Detection

Halt

Frozen

Changing Stable

Zone 4

The object exits from detection.

No detection

Active

Adapting

Doc ID 15699 Rev 7

STM8T141 STM8T processing

Note:

To prevent an object under detection from influencing the reference value, the ECF is halted as soon as a detection happens. Consequently, the reference is frozen.

In order to be able to recover from a sudden environment change, the reference freeze ends after a maximum programmable delay called the “reference freeze timeout” (t

RFT

When a detection lasts longer than the t

RFT

, the ECF is enabled again and the reference moves toward the detection signal. After a short period of time, the difference between the signal and the reference become smaller than the detection threshold and the device reports no detection.

Reference freeze timeout was incorrectly called “recalibration timeout” in previous versions of this document.

Figure 9.

Reference freeze timeout

.UMBEROFCOUNTS

2EFERENCE

3IGNAL

2EFERENCE$4H

.ODETECTION

$ETECTION

%#&FROZEN

.ODETECTION

%#&ACTIVE

3IGNALLIMIT

T 2&4

%#&FREEZE

TIMEOUT

-ASKEDDETECTION

WINDOW

See max values of t

RFT

in Table 16: General capacitive sensing characteristics .

Between the moment when the finger is removed from the sensor and the instant the reference - D

curve crosses the signal limit, the device is unable to detect a new touch. This delay is called “ masked detection window” . It depends on the environmental change or object signal variatio n speed inside the electrode’s field. The detection threshold also impac ts the masked detection window.

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STM8T processing STM8T141

The debounce filter mechanism works together with the ECF to dramatically reduce the effects of noise on the touch and proximity detection. Debouncing is applied to acquisition samples to filter undesired abrupt changes.

The number of consecutive detection debounce count (DDC) and end of detection debounce count (EDDC) needed to identify a proximity/touch detection are defined in

Section 9.5: Capacitive sensing characteristics on page 33 .

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STM8T141

6 Typical application diagram

Typical application diagram

Figure 10.

Typical application shematic

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3HIELD

3ENSINGELECTRODE

'.$

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'.$

If the active shield is not used, The SHLDIN pin must be grounded, SHLDOUT should be left unconnected, and

SHIELD can be removed.

Use COG or NPO or higher grade capacitor.

The smaller the value of the R

SHIELD

resistor, the better its effect but, the greater the device consumption.

Pin TOUT/POUT can directly drive a HV FET (as shown in

Figure 11

) that, in turn, can drive any load.

Figure 11.

Possible load configurations

Lo a d volt a ge

TOUT/POUT

Lo a d PO S

1 G

GND

Lo a d NEG

Lo a d PO S

Rel a y on Lo a d termin a l s to

S witch a ny High

Volt a ge Lo a d

L ED as L o a d

Lo a d PO S

Low Volt a ge DC

Light B u l b as Lo a d

LED

Lo a d NEG Lo a d NEG Lo a d NEG a i1552 3

A touch or proximity detection is defined as an actuation (high = logical '1' and

 low = logical '0').

Doc ID 15699 Rev 7 17/50

Device operation STM8T141

7.1

Note:

The STM8T141 can be configured through a set of selectable one-time programmable

(OTP) option bytes. These options can be used in their default (unconfigured) state or set for specific applications. For large orders, preconfigured devices are available (please refer to

Section 11: Ordering information ).

●

The STM8T141 can be configured to act as a touch or proximity detection device. A number of other options are also user programmable, including:

● Four output modes

– Active mode

– Toggle mode

– 3-second Latch mode

– 30-second Latch mode

TOUT/POUT output mode selection

Four detection thresholds

●

– Two for touch detection

– Two for proximity detection

Four power modes

– Normal power mode

●

– Three low power modes

Reference freeze timeout

Option byte description

A set of tools is supplied by STMicroelectronics to program the user OTP options for prototyping purposes. Please refer to

Section 12: STM8T141 development tools

for more details.

Devices that are not yet programmed (“blank” devices) are delivered cleared (at value ‘0’) for all bits.

Table 5.

Option byte no.

Option bytes

Bit 7 Bit 6

OPT1

OPT0 Power mode

Bit 5

Reserved

Option bits

Bit 4

Detection threshold

Bit 3 Bit 2 Bit 1 Bit 0

Factory default setting

Charge

Sampling period transfer frequency

Reserved 0xX0

Reference freeze timeout

TOUT/POUT output mode

0x00

The user options allow the STM8T141 to be customized for each specific application.

Default values for the oscillator, conversion rate (t

SAMPLING

), filter freeze and device reset settings should be used initially for first designs.

18/50 Doc ID 15699 Rev 7

STM8T141 Device operation

Table 6.

Option byte no.

Option byte description

OPT1

OPT0

Description

Bits [7:3] : Reserved

Bit 2 : Sampling period (t

SAMPLING

0: Conversion period is 20 ms



)

( Section 7.6: Sampling period )

1: Conversion period is 10 ms

Bit 1 : Charge transfer frequency (f

TRANSFER

) (

Section 7.5: Charge transfer frequency )

0: 125 kHz



1: 250 kHz

Bit 0 : Reserved

Bits [7:6] : Power mode

( Section 7.4: Power modes

)

00: Low Power mode with Zoom



01: Normal Power mode



10: Extreme Low Power mode with Zoom



11: Extreme Low Power mode

Bits [5:4] : Detection threshold (

Section 7.3: Detection threshold )

00: Standard proximity



01: Standard touch



10: Sensitive proximity



11: Sensitive touch

Bits [3:2] : Reference freeze timeout

( Section 5.3.2: Reference freeze timeout

)

00: 15-second reference freeze timeout



01: 45-second reference freeze timeout



10: Reserved



11: Infinite reference freeze

Bits [1:0] : TOUT/POUT output mode (

Section 7.2: TOUT/POUT output mode )

00: Active mode



01: Toggle mode



10: 3-second Latch mode



11: 30-second Latch mode

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20/50

Device operation STM8T141

7.2 TOUT/POUT output mode

Four output modes are available on the STM8T141:

●

Active mode

Toggle mode

3-second Latch mode

30-second Latch mode

For each output operation described, touch or proximity detection can be used. Upon the detection of either of these actions, the TOUT/POUT pin will latch high, otherwise the

TOUT/POUT pin stays low. The detailed working of each user interface is described below.

The TOUT/POUT pin is active high, and can source enough current to directly drive a LED.

The pin is sourced from V

when active. The TOUT/POUT pin always goes high for a minimum time of t

HIGH

. For more information, please refer to

Section 9: Electrical characteristics .

Bits [1:0] of option byte OPT0 are used to select the correct output mode.

7.2.1 Active

Upon the detection of an actuation, the condition of the TOUT/POUT pin will change to high

and stay high for as long as the touch or proximity detection condition occurs. Figure 12

illustrates this output operation.

Figure 12.

Active mode output operation

4OUCHPROXIMITYDETECTION

$ETECTION

.ODETECTION

4/540/54

(IGH

,OW

Doc ID 15699 Rev 7

STM8T141 Device operation

7.2.2 Toggle

Upon the detection of an actuation, the TOUT/POUT pin will toggle between high and low.

Thus if TOUT/POUT is low, an actuation will change it to high, and also if TOUT/POUT is high, an actuation will change it to low.

Figure 13

illustrates this output operation.

Figure 13.

Toggle mode output operation

4OUCHPROXIMITYDETECTION

$ETECTION

.ODETECTION

4/540/54

(IGH

,OW

Upon the detection of an actuation the TOUT/POUT pin will latch high for 3 seconds minimum. If the actuation occurs for longer than 3 seconds, the TOUT/POUT pin will stay high and will only go low when the actuation stops.

Figure 14.

3-second latch mode output operation

4OUCHPROXIMITYDETECTION

$ETECTION

.ODETECTION

4/540/54

SEC

(IGH

,OW

SEC

4IMETHATTOUCHORPROXIMITY

DETECTIONISSTILLACTIVE

Doc ID 15699 Rev 7 21/50

22/50

Device operation STM8T141

Upon the detection of an actuation, the TOUT/POUT pin will latch high. After 30 seconds from when the actuation stops, the TOUT/POUT pin will go low.

If the TOUT/POUT pin is high and another actuation occur before the 30 seconds has expired, the counter will reset and only 30 seconds after the new actuation has stopped, will the TOUT/POUT pin go low.

Figure 15

illustrates this output operation.

Figure 15.

30-second latch mode output operation

4OUCHPROXIMITYDETECTION

$ETECTION

.ODETECTION

4/540/54

(IGH

SEC

,OW

SEC SEC

The user has a choice between four detection threshold levels (D

) at which the touch or proximity detection condition is triggered. This depends on which threshold configuration is selected. See

Table 7 for more details regarding the detection threshold selections.

Bits [5:4] of option byte OPT0 are used to select the correct detection threshold levels.

Table 7.

Sensitivity

Detection thresholds

Most sensitive

Th setting

Sensitive proximity threshold

Standard proximity threshold

Sensitive touch threshold

Least sensitive Standard touch threshold

Description

Proximity for battery-powered applications.

Proximity with good ground. Contact through



3 mm acrylic glass and no ground.

Contact through thin acrylic glass with battery application.

Contact through thin dielectric with good ground.

Doc ID 15699 Rev 7

STM8T141 Device operation

●

The STM8T141 device offers four power modes. The low power modes are specifically designed for battery applications:

Normal Power mode

Low Power mode with Zoom

Extreme Low Power mode with Zoom

Extreme Low Power mode

Burst cycles can occur either every 10 ms or 20 ms according to the selected sampling period (t

SAMPLING

). By selecting low power modes, extra delays are interlaced between bursts. This improves the device current consumption at the expense of the response time.

Bits [7:6] of option byte OPT0 are used to select the correct power mode.

Table 8.

Low power period according to selected power mode

Power mode Condition

Normal Power mode

Touch or proximity detection

Low Power mode with Zoom

Untouched

Touch or proximity detection

Extreme Low Power mode with

Zoom

Untouched

Extreme Low Power mode t

value

4 x t

SAMPLING

16 x t

SAMPLING

16 x t

SAMPLING

When in Normal Power mode, burst cycles occur at the rate of t

SAMPLING

. No extra delays

are added between burst cycles ( Figure 16 ).

Figure 16.

Charge cycle timing diagram in Normal Power mode

Burst cycle duration t

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

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24/50

Device operation

7.4.2

STM8T141

Low Power mode with Zoom

With the STM8T141 in Low Power mode with Zoom, burst cycles occur every 5th t

SAMPLING period (or 20% of the Normal Power mode).

Once activity is detected, the STM8T141 device wakes up from Low Power mode with Zoom to Normal Power mode with charge cycles occurring every t

SAMPLING

period. The device will return to Low Power mode after an end of low power period (t

ELP

) when no touch or proximity detection conditions are detected. This enables the device to reduce power consumption when not in use, and still have a sufficient response time when needed

(

Figure 17

Figure 17.

Charge cycle timing diagram in Low Power mode with Zoom

Burst cycle duration

Zoom to Normal mode after touch or proximity detection occurred t

1 2 3 4 t

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

7.4.3 Extreme Low Power mode with Zoom

With the STM8T141 in Extreme Low Power Mode with Zoom, burst cycles only occur every

17th t

SAMPLING

period (or 5.88% of the Normal Power mode).

Once activity is detected, the STM8T141 device wakes up from Extreme Low Power mode and Zoom to Normal Power mode with charge cycles occurring every t

SAMPLING

. The device will return to Low Power mode after an end of low power period (t

ELP

) when no touch or proximity detection conditions are detected. This enables the device to reduce power consumption when not in use and still have a sufficient response time when needed

(

Figure 18

Figure 18.

Charge cycle timing diagram in Extreme Low Power mode with Zoom

Burst cycle every 17th t

SAMPLING

period

Zoom to Normal mode after touch or proximity detection occurred t

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 t

Doc ID 15699 Rev 7

STM8T141

7.4.4

Device operation

Extreme Low Power mode

With the STM8T141 in Extreme Low Power mode, burst cycles only occur every 17th t

SAMPLING

period (or 5.88% of the Normal Power mode), thus adding 16 extra delays of t

SAMPLING

between charge cycles to conserve power.

This reduces the amount of burst cycles in Extreme Low Power mode even more than Low

Power mode which in turn saves even more power but comes at the expense of a higher system response time (

Figure 19

Figure 19.

Charge cycle timing diagram in Extreme Low Power mode

Burst cycle every 17th t

SAMPLING

period t

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 t

7.5 Charge transfer frequency

The STM8T141 offers two charge transfer frequencies. The charge transfer frequency must be adjusted depending on the C

capacitor. The charge transfer frequency may need to be raised to 250 kHz in order to reduce t

BURST

when the C

capacitance is large.

● 125 kHz

● 250 kHz

Bit 1 of option byte OPT1 is used to select the correct charge transfer frequency.

●

The default sampling period (t

SAMPLING

) is configurable in order to allow different compromises between power consumption and conversion rates:

20-ms sampling rate to reduce average power consumption

10-ms sampling rate to increase detection response time

When using a faster sampling rate (t

SAMPLING

= 10 ms), all the timing values of the Power modes will occur at twice the speed.

BIt 2 of option byte OPT1 is used to select the correct conversion period.

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Design guidelines STM8T141

Note:

●

The STM8T141 offers a built-in shielding function. This function provides the following advantages for designing the end-application:

Sensing electrode separated from sealed electronics.

Sensing wire shielded from unwanted environmental interferences.

Enhanced proximity detection when used with battery (DC) applications.

The shield principle consists in actively driving the shield plane or element with the same signal as that of the electrode. The parasitic capacitance between the electrode and the shield does not need to be charged anymore and its effect on the sensitivity is cancelled.

Grounding the shield reduces the sensitivity of the keys and may render the system unusable.

Note:

Ideally, a coaxial cable is used for the shield. A R

(typically 2 k



) resistor should be connected to the C

pin. The other side of the R

resistor should be connected to the center core of the coaxial cable. The SHLDOUT pin should be connected to the metallic shield part of the coaxial cable. A pull-up resistor (R

SHIELD

) should be added between SHLDOUT and

as shown in

Figure 20 .

The example shown in

Figure 20

is given for R

= 2 k



, R

SHIELD

= 100 k



, and V

This setup has been successfully implemented with a coaxial cable of up to 4 m.

= 5 V

(a)

A longer coaxial cable could be used, but this would mean decreasing the R

SHIELD

resistor, and consequently increasing current consumption.

A smaller R

SHIELD

Figure 20

ensures better shielding but increases current consumption (see

26/50 a.

must range from 4.5 to 5.5 V to use the shield function.Please refer to

Table 12: Operating characteristics

for the correct power supply operating voltage when using the shield function.

Doc ID 15699 Rev 7

STM8T141 Design guidelines

Figure 20.

Connecting the shield (coaxial cable implementation)

VDD

Coaxial cable

100 k

S HIELD

Pl as tic j a cket

Met a l s hield

S HLDOUT

Center core

2 k

S HLDIN

Dielectric in su l a tor a i15527

Several factors impact device sensitivity:

●

The sensing electrode material and size

The touch panel material and thickness

The board layout and in particular the sensing signal tracks

The value of the sampling capacitor (C

) for proximity thresholds only

The ground coupling of the object (finger or hand) and sensor.

The touch or proximity detection threshold selected by the option byte.

8.2.1 C

influence on sensitivity

In touch mode, the Cs capacitor value has no influence on the sensitivity as the thresholds are relative to the actual reference value. In proximity mode, the Cs value allows the sensivity to be tuned.

A higher sampling capacitor value increases the resolution and the sensitivity but also the charging time. Decreasing the sampling capacitor value therefore decreases the sensitivity.

For more details, please refer to application note AN2966 .

8.2.2 PCB layout and construction

The PCB traces, wiring, and components associated or in contact with C

pins become touch sensitive and should be treated with caution to limit the touch area to the desired location. As an example, multiple touch electrodes connected to a sensing channel can be used to create control surfaces on both sides of an object.

It is important to limit the amount of stray capacitance on the C

pin. This can be done by minimizing trace lengths and widths to achieve for higher gain without using higher values of

. To minimize cross-coupling, electrode traces from adjacent sensing channel should not run close to each other for long distances. For detailed information on the impacts of the first three factors, refer to application note AN2869.

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Design guidelines

8.3

STM8T141

Influence of power supply variation

The stability of the device power supply is critical in order to provide a precise and repeatable capacitance measure. For this reason, a linear regulator is embedded into the device to provide the best power supply noise rejection possible.

Even with the embedded regulator, variations of the power supply voltage may have an impact on the measured signal, especially in proximity configurations with a large acquisition gain and small detection threshold.

A variation of the power supply voltage (



V) induces a variation of the signal burst count

(



BC) according to

Equation 1 .

Equation 1



BC = G

   

The gain, G, of the acquisition is the ratio Cs/Cx.

The parameter

is the power supply rejection ratio.

For stability reasons, it is advised to limit



BC to less than half the detection threshold. If

is less than 2.9 V, special care should be taken of the supply quality. An external voltage regulator may be necessary.

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STM8T141 Electrical characteristics

9.1.1

Unless otherwise specified, all voltages are in reference to V

Minimum and maximum values

Unless otherwise specified, the minimum and maximum values are guaranteed in the worst conditions of ambient temperature and supply voltage by tests in production on 100% of the devices with an ambient temperature at T

= 25 °C and T

= T

A max (given by the selected temperature range).

Data based on characterization results, design simulation and/or technology characteristics are indicated in the table footnotes and are not tested in production. Based on characterization, the minimum and maximum values refer to sample tests and represent the mean value plus or minus three times the standard deviation (mean ±3



Unless otherwise specified, typical data are based on T

A given only as design guidelines and are not tested.

= 25 °C, and V

= 5 V. They are

Unless otherwise specified, all typical curves are given only as design guidelines and are not tested.

The loading conditions used for pin parameter measurement are shown in Figure 21 .

Figure 21.

Pin loading conditions

Output pin

50 pF

Doc ID 15699 Rev 7 29/50

Electrical characteristics

9.2

STM8T141

Absolute maximum ratings

Stresses above those listed as “absolute maximum ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device under these conditions is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability.

Table 9.

Symbol



Voltage characteristics

Ratings

Supply voltage

Maximum value

5.5

Table 10.

Current characteristics

Symbol

VDD

VSS

Ratings

Total current into V

power lines (source)

(1)

Total current out of V

ground lines (sink)

(1)

Output current sunk by output pin

Output current sourced by output pin

Maximum value

All power (V

) and ground (V

) lines must always be connected to the external supply.

Table 11.

Thermal characteristics

Symbol Ratings

STG

Value



65 to +150

Storage temperature range

Junction temperature range (SO8 narrow and UFDFPN8 packages)

Unit

Unit mA

Unit

°C

9.3.1 General operating conditions and supply characteristics

Table 12.

Operating characteristics

Symbol

Parameter

Supply voltage

Condition

Shield feature not used



Shield feature used

VDD

Operating temperature

Turn-on slope (Rise time rate)

Turn-off slope (Fall time rate)

This constraint must be respected only if the voltage does not reach 0 V.

Min.

Max.

Unit

2.0

4.5

-40

5.5

°C

0 1

V/s

(1) 

30/50 Doc ID 15699 Rev 7

STM8T141

9.3.2

Note:

Electrical characteristics

Average current consumption

Test conditions: T

= 25 °C, C

= 20 pF, C

= 47 nF and R

= 2 k



Table 13.

Average current consumption without shield

Symbol Parameter Conditions

Normal Power mode

Low Power

Extreme Low Power mode

– Shield output unconnected

– Shield input grounded

– Options other than Low Power are left in default configuration

Data based on characterization results, not tested in production.

Typ.

Max.

Unit

30 45

(1)

µA

Consumption does not depend on either detection threshold or acquisition rate.

Figure 22.

average current consumption vs R

SHIELD

) $$

23()%,$K/HMS

%XT,0

ExtLP = External Low Power mode

LP = Low Power mode

NP = Normal Power mode

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Electrical characteristics STM8T141

9.4

Table 14.

Output pin characteristics

Symbol Parameter

= 5 V

= 3.3 V

= 2.9 V

= 2.0 V

= 5 V

OH t

HIGH t

LOW

= 3.3 V

= 2.9 V

= 2.0 V

Output minimum high time

Output minimum low time

Conditions

LOAD

= 8 mA

LOAD

= 4 mA

LOAD

= 2 mA

LOAD

= 4 mA

LOAD

= 2 mA

LOAD

= 2 mA

LOAD

= 1 mA

LOAD

= –2 mA

LOAD

= –4 mA

LOAD

= –8 mA

LOAD

= –2 mA

LOAD

= –4 mA

LOAD

= –2 mA

LOAD

= -100 µA

Regulator and reference voltage

Table 15.

Regulator and reference voltage

Symbol Parameter

C ref

Voltage regulator decoupling capacitance

(1)

V reg

Regulated voltage during acquisition

V trip

End of acquisition reference voltage

Equivalent serial R resistor



0.2



at 1 MHz.

Typ.

2.5

1.8

4.4

3.9

3.0

2.7

1200

540

250

650

320

400

300

4.7

Max.

1600

750

450

1000

500

Unit mV

V ms

Min.

Typ.

2.1

0.68

Max.

Unit

µF

Doc ID 15699 Rev 7

STM8T141

9.5

Electrical characteristics

Capacitive sensing characteristics

Table 16.

General capacitive sensing characteristics

(1)

Symbol Parameter Min.

Typ.

Charge-transfer frequency at 125-kHz setting f

TRANSFER

Charge-transfer frequency at 250-kHz setting

Scanning period at 10-ms setting t

SAMPLING

Scanning period at 20-ms setting

Low Power t

LP t

ELP

Extreme Low Power

Time before switching back to Low

Power mode t

RFT

(2)

15 s reference freeze timeout

45 s reference freeze timeout t

BURST

DDC

Burst detection

Detection debounce count

EDDC End of detection debounce count

Proximity detection threshold

(3)

Sensitive proximity detection threshold

Touch detection threshold

Sensitive touch detection threshold

185

7.5

125

250

4 t

SAMPLING

16 t

SAMPLING

540

– 8

– 2

Ref./16

Ref./32

 (4)

Power supply rejection ratio V

DDMIN

< 3 V)

Power supply rejection ratio (3.5 V < V

< V

DDMAX

)

0.0250

0.0005

Values guaranteed by design.

See t

RFT

Figure 9: Reference freeze timeout

Reference value (Ref.) described in Section 5.3.3: Debounce filter on page 16 .

Between 3 V and 3.5 V,



 evolves as shown in

Figure 23 .

Max.

160

315

12.5

Unit kHz ms s t

TRANSFER

Counts

Count/V

Doc ID 15699 Rev 7 33/50

Electrical characteristics

Figure 23.

Sigma variation across V

STM8T141

34/50

6$$6

Table 17.

Response times

(1)

Mode t

SAMPLING

= 10 ms t

SAMPLING

= 20 ms

Min.

Max.

Min.

Max.

Unit

Normal Power mode

Low Power with Zoom mode

Extreme Low Power with Zoom mode

Extreme Low Power mode

510

100

250

850

1020

100

200

500

1700 ms

Values guaranteed by design.

Table 18.

External sensing component characteristics

Symbol Parameter Min.

Typ.

Max.

Sampling capacitor (COG or NPO type)

(1)

Equivalent touch capacitance

Electrode serial resistance

SHIELD

Shield pull-up resistance 1

1. For more information about capacitors, please refer to Application note: AN2966.

x C

100

1000

Unit nF

kOhm

Doc ID 15699 Rev 7

STM8T141 Electrical characteristics

9.6.1

Susceptibility and emission tests are performed on a sample basis during product characterization.

Both the sample and its applicative hardware environment ( Figure 10 ) are mounted on a

dedicated specific EMC board defined in the IEC61967-1 standard.

Functional EMS (electromagnetic susceptibility)

While running in the above described environment the product is stressed by two electromagnetic events until a failure occurs.

● ESD : Electrostatic discharge (positive and negative) is applied on all pins of the device until a functional disturbance occurs. This test complies with the IEC 1000-4-2 standard.

● FTB : A burst of fast transient voltage (positive and negative) is applied to V

and V through a 100 pF capacitor, until a functional disturbance occurs. This test complies

SS with the IEC 1000-4-4 standard.

A device reset allows normal operations to be resumed. The test results are given in

Table 19

based on the EMS levels and classes defined in application note AN1709.

Table 19.

EMS data

Symbol

FESD

EFTB

Parameter Conditions

Voltage limits to be applied on any pin to induce a functional disturbance

Fast transient voltage burst limits to be applied through 100pF on V

and V

SS pins to induce a functional disturbance



5 V, T



+25 °C, SO8

(Narrow) package, complies with IEC 1000-4-2



5 V, T



+25 °C, SO8

(Narrow) package, complies with IEC 1000-4-4

Level/class

Doc ID 15699 Rev 7 35/50

Electrical characteristics STM8T141

9.6.4

Emission tests conform to the IEC61967-2 standard for board layout and pin loading. Worse case EMI measurements are performed during maximum device activity.

Table 20.

EMI data

Symbol

EMI

Parameter

Peak level

SAE EMI level

Peak level

SAE EMI level

General conditions

Monitored frequency band



5 V, T



+25 °C,



SO8 (Narrow) package,



Complies with SAE

J1752/3, No finger on touch electrode



5 V, T



+25 °C,



SO8 (Narrow) package,



Complies with SAE

J1752/3, Finger on touch electrode

0.1 MHz to 30 MHz

30 MHz to 130 MHz

130 MHz to 1 GHz

0.1 MHz to 30 MHz

30 MHz to 130 MHz

130 MHz to 1 GHz

Data based on characterization results, not tested in production.

OSC =

500 kHz

(1)

-4

-9

-6

-1

-8

-7

Unit dBµV dBµV

Absolute maximum ratings (electrical sensitivity)

Based on two different tests (ESD and LU) using specific measurement methods, the product is stressed in order to determine its performance in terms of electrical sensitivity.

For more details, refer to the application note AN1181.

9.6.5 Electrostatic discharge (ESD)

Electrostatic discharges (3 positive then 3 negative pulses separated by 1 second) are applied to the pins of each sample according to each pin combination. The sample size depends on the number of supply pins in the device (3 parts*(n+1) supply pin). This test conforms to the JESD22-A114A/A115A standard. For more details, refer to the application note AN1181.

Table 21.

ESD absolute maximum ratings

Symbol Ratings Conditions Class

Maximum value

(1)

Unit

ESD(HBM)

ESD(CDM)

Electrostatic discharge voltage

(Human body model)

Electrostatic discharge voltage

(Charge device model)





+25°C, conforming to JESD22-A114



+25°C, conforming to JESD22-C101

Data based on characterization results, not tested in production

2000

1000

36/50 Doc ID 15699 Rev 7

STM8T141 Electrical characteristics

Two complementary static tests are required on 10 parts to assess the latchup performance.

●

A supply overvoltage (applied to each power supply pin) and

A current injection (applied to each input, output and configurable I/O pin) are performed on each sample.

This test conforms to the EIA/JESD 78 IC latchup standard. For more details, refer to application note AN1181.

Table 22.

Electrical sensitivities

Symbol Parameter Conditions Class

(1)

LU Static latchup class



+25 °C



+85 °C

Class description: A Class is an STMicroelectronics internal specification. All its limits are higher than the

JEDEC specifications, that means when a device belongs to class A it exceeds the JEDEC standard. B class strictly covers all the JEDEC criteria (international standard).

Doc ID 15699 Rev 7 37/50

Package characteristics STM8T141

In order to meet environmental requirements, ST offers these devices in different grades of

ECOPACK® packages, depending on their level of environmental compliance. ECOPACK® specifications, grade definitions and product status are available at www.st.com

ECOPACK® is an ST trademark.

10.1 Package mechanical data

10.1.1 SO8 package mechanical data

Figure 24.

SO8-lead plastic small outline - package outline h x 45˚

A2 A c ccc b e

0.25 mm

GAUGE PLANE k

E1 E

SO-A

38/50 Doc ID 15699 Rev 7

STM8T141 Package characteristics

Table 23.

8-lead plastic small outline - package mechanical data millimeters inches

(1)

Symbol

Min.

Typ.

Max.

Min.

Typ.

Max.

e h k

A2 b c ccc

(2)

(3)

5.800

3.800

0.250

0°

0.400

0.100

1.250

0.280

0.170

4.800

4.900

6.000

3.900

1.270

1.040

1.750

0.250

0.480

0.230

0.100

5.000

6.200

4.000

0.500

8°

1.270

0.0039

0.0492

0.0110

0.0067

0.1890

0.2283

0.1496

0.0098

0°

0.0157

0.1929

0.2362

0.1535

0.0500

0.0409

Values in inches are rounded to 4 decimal digits

Dimension D does not include mold flash, protrusions or gate burrs. Mold flash, protrusions or gate burrs shall not exceed 0.15mm in total (both side).

Dimension E1 does not include interlead flash or protrusions. Interlead flash or protrusions shall not exceed 0.25 mm per side.

0.2441

0.1575

0.0197

8°

0.0500

0.0689

0.0098

0.0189

0.0091

0.0039

0.1969

Doc ID 15699 Rev 7 39/50

Package characteristics STM8T141

10.1.2 UFDFPN8 package mechanical data

Figure 25.

UFDFPN8-lead ultra thin fine pitch dual flat package (MLP) package outline

D e b

E E2

D2 ddd

UFDFPN-01

Table 24.

8-lead ultra thin fine pitch dual flat - package mechanical data millimeters inches

(1)

Symbol

Min Typ Max Min Typ Max

E2 e b

0.450

0.000

0.200

1.900

1.500

2.900

0.100

0.550

0.020

0.250

2.000

1.600

3.000

0.200

0.500

0.600

0.050

0.300

2.100

1.700

3.100

0.300

0.0177

0.0000

0.0079

0.0748

0.0591

0.1142

0.0039

0.0217

0.0008

0.0098

0.0787

0.0630

0.1181

0.0079

0.0197

0.400

0.450

0.500

0.150

0.0157

0.0177

0.0197

0.0059

Tolerance ddd

(2)

0.300

millimeters

0.0118

inches

0.080

0.0031

Values in inches are rounded to 4 decimal digits

Applied for exposed die paddle and terminals. Exclude embedding part of exposed die paddle from measuring.

0.0236

0.0020

0.0118

0.0827

0.0669

0.1220

0.0118

40/50 Doc ID 15699 Rev 7

STM8T141 Package characteristics

10.2 Package thermal characteristics

The maximum chip junction temperature (T

Jmax

) must never exceed the values given in

Table 12: Operating characteristics on page 30

The maximum chip-junction temperature, T

Jmax

, in degrees Celsius, may be calculated using the following equation:

Jmax

= T

Amax

+ (P

Dmax



)

Where:

●

Amax

is the maximum ambient temperature in





is the package junction-to-ambient thermal resistance in



C/W

●

Dmax

is the sum of P

INTmax

and P

I/Omax

Dmax

= P

INTmax

+ P

I/Omax

)

INTmax

is the product of I

DD and V

, expressed in Watts. This is the maximum chip internal power.

● P

Where:



I/Omax

represents the maximum power dissipation on output pins





) +



((V

-V

)*I

 taking into account the actual V the application.

OL and V

of the I/Os at low and high level in

Table 25.

Thermal characteristics

(1)

Symbol



Parameter

Thermal resistance junction-ambient



SO8 (Narrow)

Thermal resistance junction-ambient



UFDFPN 8 (2 x 3 mm)

Value

130

120

Thermal resistances are based on JEDEC JESD51-2 with 4-layer PCB in a natural convection environment.

Unit

°C/W

JESD51-2 integrated circuits thermal test method environment conditions - natural convection (still air). Available from www.jedec.org.

Doc ID 15699 Rev 7 41/50

42/50

Ordering information STM8T141

Figure 26.

STM8T141 ordering information scheme

Example: STM8T 141 A M XXXY TR

Device type

STM8T: ST touch sensing MCU

Device sub-family

141 = 1 channel/proximity

Pin count

A: 8 pins

Package

M: S08 (small outline)

U: FPN (dual flat no lead)

Device configuration

XXXY: device with specific configuration

(1)

61T: OTP blank device (all user bits set to 0)

(2)

Packing

No character: tray or tube

TR: tape and reel

See

Table 26: Orderable favorite device lists

and the explanation below of “in factory option byte programming service”

The STM8T141 OTP devices are available for production and development. These parts are blank devices with unconfigured option bytes (all option bits are set to ‘0’). For more

 information, please refer to

Section 7: Device operation .

Doc ID 15699 Rev 7

STM8T141 Ordering information

11.2 Orderable favorite device lists

Table 26.

Orderable favorite device lists

Option byte configuration

(1)

Part numbers

Config.

Sampling period

Charge transfer frequency

Power modes

Default config.

(OTP)

20 ms

125 kHz

Low Power mode with zoom

Please refer to Section 7: Device operation

Detection threshold

Reference freeze timeout

TOUT/

POUT output mode

Standard proximity

Sensitive touch

15 s

Infinite

Active mode STM8T141AM61T STM8T141AU61TTR

Active mode

SO8

Not yet available

UFDFPN8

STM8T141AU MAJ1 TR

(XXXY = MAJ1)

For specific configurations not listed in

Table 26: Orderable favorite device lists ,

in-factory option byte programming is available on customer request and for large order quantities.

Customers have to fill out the option list (see below) and send it back to STMicroelectronics.

Customers are then informed by STMicroelectronics about the ordering part number corresponding to the customer configuration. The XXXY parameter of the final ordering part number (e.g. STM8T141AMXXXY) depends on the device configuration and is assigned by

STMicroelectronics.

Doc ID 15699 Rev 7 43/50

Ordering information

S TM 8 T141 pro g rammin g s ervice option li s t

(la s t update: February 2010)

Cu s tomer name:

Addre ss :

Contact name:

Phone number:

Select the package type (tick one box)

STM8T141AM6 - S08 or STM8T141AU6 DFN8

Cu s tomer s ettin gs

(tick one box by option)

Sa mpling period ( s ee S ection 7.6: Sa mpling period )

10 m s sa mpling period

20 m s sa mpling period (1)

Ch a rge tr a n s fer fre qu ency ( s ee S ection 7.5: Ch a rge tr a n s fer fre qu ency)

125 kHz

(1)

250 kHz

Power mode s ( s ee S ection 7.4: Power mode s )

Norm a l Power mode

Low Power mode with Zoom

(1)

Extreme Low Power mode with Zoom

Extreme Low Power mode

Detection thre s hold ( s ee S ection 7.

3 : Detection thre s hold )

S en s itive proximity

S t a nd a rd proximity (1)

S en s itive to u ch

S t a nd a rd to u ch

Reference freeze timeo u t ( s ee S ection 5.

3 .2:Reference freeze timeo u t )

15s econd reference freeze timeo u t (1)

45s econd reference freeze timeo u t

Infinite reference freeze

TOUT/POUT o u tp u t mode ( s ee S ection 7.2: TOUT/POUT o u tp u t mode )

Active mode (1)

Toggle mode

3 s econd L a tch mode

3 0s econd L a tch mode

P a ck a ging

T a pe & reel

T ub e

Comment :

D a te

S ign a t u re :

Configuration by default in OTP devices.

44/50 Doc ID 15699 Rev 7

STM8T141

12 STM8T141 development tools

STM8T141 development tools

STM8T141 evaluation kit

The STM8T141-EVAL is an evaluation kit which introduces developers to the STM8T141. It contains an STM8T141 evaluation board, plus a set of preconfigured plug-in modules which allow the STM8T141 device performances to be evaluated in either touch or proximity detection.

Figure 27.

STM8T141-EVAL evaluation kit

Doc ID 15699 Rev 7 45/50

STM8T141 development tools STM8T141

STM8T141 “blank” modules

An additional box of 10 STM8T141 “blank” modules (STM8T141AM-MOD) can be ordered

separately, where the device option bytes are left unprogrammed (see Figure 28 ).

Figure 28.

STM8T141 blank module box

The above figure is not binding.

46/50 Doc ID 15699 Rev 7

STM8T141 STM8T141 development tools

Programming tool

Figure 29

shows the STM8T141-EVAL programming tool.

To program the device option bytes so that the device can be tested in different configurations, the following materials are available:

● A programming socket board (STM8T14X-SB). When connected to the programming dongle, this board allows SO8 and DFN8 devices as well as plug-in modules delivered in the evaluation kit to be programmed.

● A programming dongle (ST-TSLINK) and its associated programming software, STVP.

Figure 29.

STM8T141-EVAL programming tool

Programming socket boards (STM8T14X-SB)

Programming dongle (ST-TSLINK)

Ordering information

Table 27.

Ordering information

Part number Order codes Description

STM8T141-EVAL STM8T141-EVAL STM8T141 evaluation kit

STM8T-MOD STM8T141AM-MOD

Box containing 10 blank modules based on

STM8T141AM61T (OTP device in SO8 package)

STM8T141 programming dongle ST-TSLINK

STM8T14X-SB

ST-TSLINK

(1)

STM8T14X-SB

(1)

STM8T141 socket board

The ST-TSLINK dongle and the STM8T14X-SB socket board are not part of the STM8T141-EVAL evaluation kit, and consequently must be ordered separately.

Doc ID 15699 Rev 7 47/50

Revision history STM8T141

48/50

Table 28.

Document revision history

Date Revision

09-Jun-2009

02-Jul-2009

31-Jul-2009

05-Oct-2009

24-Feb-2010

Changes

Initial release.

range changed to 2.9 to 5.5V. Table 12 and

Table 14

updated.

Internal voltage regulator bypassed configuration removed.

DDLP

removed from

Table 13

Upgraded document from Preliminary Data to full Datasheet.

Updated oscillator information in Figure 1: STM8T141 block diagram on page 8 .

Added detection threshold values in

Table 16: General capacitive sensing characteristics on page 33 .

Updated values in Table 17: Response times on page 34

Updated

Section 11: Ordering information .

Section 11.2: Orderable favorite device lists

: added information on option byte programming; added option list.

Added

Section 12: STM8T141 development tools

Lower operating supply voltage changed from 2.9 V to 2.0 V. The

following tables were impacted: Table 1: Device summary ,

Table 12:

Operating characteristics ,

Table 13: Average current consumption without shield ,

Table 16: General capacitive sensing characteristics , and Table 16: General capacitive sensing characteristics .

Introduced trademark for ProxSense (ProxSense™)

Throughout document, “sensitivity threshold or level” replaced with

“detection threshold”, “automatic recalibration” with “reference freeze timeout”, “S

” with “D

”, and “SO” with “SO8”.

Section 2: Block diagram

: replaced ‘capacitive sensing engine’ with

‘ProxSense engine’.

Added

Figure 3: UFDFPN8 pinout

Updated

Table 2: STM8T141 pin descriptions .

Renamed Section 4

STM8T ProxSense technology

Renamed Section 4.2

as Charge transfer acquisition principle

and updated text.

Figure 5: STM8T measuring circuitry : updated.

Figure 6: Conversion period examples : updated.

Sections 4.3 renamed

Section 5: STM8T processing . Section re-

organised and reworked with new figures and tables added.

Section 6: Typical application diagram

: removed introductory text;

modified Figure 10 , modified footnote 1, added footnote 2, added text

regarding R

SHIELD

resistor, define a touch or proximity detection.

Section 7: Device operation

: Re-organisation of text; removed reference related to low power modes.

Section 7.1: Option byte description : added reference to

Section 12

Table 5: Option bytes : updated factory default setting of OPT1,

recalibration timeout renamed reference freeze timeout.

Doc ID 15699 Rev 7

STM8T141 Revision history

Table 28.

Document revision history (continued)

Date Revision Changes

24-Feb-2010

01-Apr-2010

28-Jun-2011

5 cont’d

: replaced “output configuration” with “output operation”.

Section 7.2.3: 3-second latch : removed some text concerning the

TOUT/POUT pin.

Renamed Section 7.3: Detection threshold

Section 7.4: Power modes

: small text changes;

Table 8 moved to this

section from Section 7.4.4: Extreme Low Power mode

Section 8.1: Shield function

: removed text about R

SHIELD

Figure 20: Connecting the shield (coaxial cable implementation) :

amended ohm symbol.

Section 8.2: Sensitivity adjustment

/ added text regarding sensitivity; updated bullet points.

Added

Section 8.3: Influence of power supply variation .

Table 12: Operating characteristics

: added t

VDD

data.

Section 9.3.2: Average current consumption

: for test conditions,



100 nF replaced with 47 nF; modified

Table 13

and note underneath

it; added Figure 22

Table 14: Output pin characteristics

: removed t

VDD

data.

Added

Section 9.4: Regulator and reference voltage and Table 15

Section 9.5: Capacitive sensing characteristics : amended Table 16

for values of f

TRANSFER

, t

RFT

, and t

BURST

; updated symbols for t

RFT

, and



; added

Figure 23 .

Table 18: External sensing component characteristics

: modified C

S parameter and R

SHIELD

min value.

Section 11: Ordering information : updated Figure 26

; added

Section 11.2

and Section 11.3

Section 11.2: Orderable favorite device lists

: updated ordering part number; added footnote to option list concerning default configuration of OPT devices, added packaging information to the option list, updated headings and date.

Section 12: STM8T141 development tools

: replaced STM8T1X1 with

STM8T141.

Added that ProxSense™ is a trademark of Azoteq.

Figure 26: STM8T141 ordering information scheme : updated footnote 2.

Programming tool

: replaced STM8T141-SB with STM8T14X-SB.

Figure 29: STM8T141-EVAL programming tool

: replaced

STM8T141-SB with STM8T14X-SB.

Table 27: Ordering information : replaced STM8T1X1-EVAL and

STM8T141-SB with STM8T141-EVAL and STM8T14X-SB respectively.

Doc ID 15699 Rev 7 49/50

STM8T141



Please Read Carefully:

Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice.

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