STMICROELECTRONICS STMPE1208SQTR

STMPE1208S
Xpander Logic™ with 12-channel touchkey
Features
■
12 touchkey capacitive sensor inputs
■
12-bit general purpose input/output (GPIO)
■
Operating voltage 2.5 − 5.5 V
■
98 μA in active mode, 60 μA in idle mode
■
Dual interrupt output pin
■
I2C interface (up to 400 kHz)
■
7 kV HBM ESD protection
■
Idle and sleep mode for low power operation
■
Advanced data filtering (AFS)
■
Environment tracking calibration (ETC)
■
Individually adjustable touch variance (TVR)
setting for all channels
■
Adjustable environmental variance (EVR) for
optimal calibration
Applications
■
Notebook computers
■
Monitors
■
Set-top boxes
■
Televisions
■
Portable media players and game consoles
■
Mobile and smart phones
■
Home entertainment systems
■
Domestic appliances
Table 1.
July 2008
QFN40
Description
The STMPE1208S is a 12-channel GPIO
capacitive touchkey sensor able to interface a
main digital ASIC via the two-line bidirectional bus
(I2C). It senses changes in capacitance using a
fully digital architecture, giving fast and accurate
results at very low power consumption. Automatic
impedance calibration ensures that changes in
environment will never affect the correct operation
of the capacitive touchkeys.
Device summary
Order code
Package
Packing
STMPE1208SQTR
QFN40
Tape and reel
Rev 3
1/51
www.st.com
51
Contents
STMPE1208S
Contents
1
Pin configuration and function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1
Power management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2
Clock setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3
I2C interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4
Power schemes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5
Capacitive sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.1
Capacitive sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.2
Capacitance compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.3
Setting of TVR and EVR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.3.1
3-stage data filtering system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.3.2
Noise filtering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.3.3
BEEP output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.3.4
Interrupt system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6
Register map and function description . . . . . . . . . . . . . . . . . . . . . . . . . 19
7
Command registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
8
Maximum rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
8.1
Recommended operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
9
Electrical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
10
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
11
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
2/51
STMPE1208S
List of tables
List of tables
Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
Table 6.
Table 7.
Table 8.
Table 9.
Table 10.
Table 11.
Table 12.
Table 13.
Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Pin assignments and description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Clocking system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
I2C addresses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Operation modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Calibration action under different scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Register summary map table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Command registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Recommended operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
DC electrical characteristics (-40 - 85 °C unless otherwise stated)) . . . . . . . . . . . . . . . . . . 44
QFN40 (5 x 5 mm) mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
3/51
List of figures
STMPE1208S
List of figures
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Figure 10.
Figure 11.
Figure 12.
Figure 13.
Figure 14.
Figure 15.
Figure 16.
Figure 17.
Figure 18.
Figure 19.
4/51
STMPE1208S pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
STMPE1208S block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Application diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
STMPE1208S operating states . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Read and write modes (random and sequential) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Power using the internal regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Power bypassing the internal regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Capacitive sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Capacitive sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Capacitance compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3-stage data filtering system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Interrupt system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Software interface (G_INT based) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Software interface (T_INT based). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
QFN40 (5 x 5 mm) package outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
QFN40 recommended footprint without ground pad VIA . . . . . . . . . . . . . . . . . . . . . . . . . . 47
QFN40 recommended footprint with ground pad VIA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
QFN40 tape information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Reel information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
STMPE1208S
Pin configuration and function
S_IN_ 8
S_IN_ 7
S_IN_ 6
GND
V25
VREG
VPH
S_IN_ 5
S_IN_ 4
STMPE1208S pin configuration
S_IN_3
Figure 1.
S_IN_2
S_IN_ 9
S_IN_1
S_IN_ 10
S_IN_0
S_IN_ 11
S_ RE F
RESET_N
GND
ID_1
STMPE1208S
ID_0
VPH
GPIO_ 5
GPIO_6
GPIO_ 4
GPIO _7
GPIO_ 3
GPIO _8
GPIO _9
5
6
SDATA
SCLK
T_INT
G_INT
GPIO_11
4
GPIO_10
3
TCLK
2
BEEP
1
GPIO_0
GPIO_ 2
GPIO_1
1
Pin configuration and function
CS00037
Table 2.
Pin assignments and description
Pin number
Pin name
Description
1
GPIO_1
General purpose I/O
2
GPIO_0
General purpose I/O
3
SDATA
I2C data
4
SCLK
I2C clock
5
T_INT
Touch interrupt
6
G_INT
General interrupt
7
BEEP
Beep output
8
TCLK
Test pin (to be grounded)
9
GPIO_11
General purpose I/O
10
GPIO_10
General purpose I/O
11
GPIO_9
General purpose I/O
5/51
Pin configuration and function
Table 2.
6/51
STMPE1208S
Pin assignments and description (continued)
Pin number
Pin name
Description
12
GPIO_8
General purpose I/O
13
GPIO_7
General purpose I/O
14
GPIO_6
General purpose I/O
15
VPH
3 − 5.5 V power supply (regulator input)
Supply to this pin is also used for powering the GPIO
16
GND
Ground
17
S_REF
18
S_IN_11
Capacitance sensing input 11
19
S_IN_10
Capacitance sensing input 10
20
S_IN_9
Capacitance sensing input 9
21
S_IN_8
Capacitance sensing input 8
22
S_IN_7
Capacitance sensing input 7
23
S_IN_6
Capacitance sensing input 6
24
GND
Ground
25
V25
2.5 V supply
26
VREG
27
VPH
28
S_IN_5
Capacitance sensing input 5
29
S_IN_4
Capacitance sensing input 4
30
S_IN_3
Capacitance sensing input 3
31
S_IN_2
Capacitance sensing input 2
32
S_IN_1
Capacitance sensing input 1
33
S_IN_0
Capacitance sensing input 0
34
RESET_IN
35
ID_1
I2C address
36
ID_0
I2C address
37
GPIO_5
General purpose I/O
38
GPIO_4
General purpose I/O
39
GPIO_3
General purpose I/O
40
GPIO_2
General purpose I/O
Touch sensing reference.
Internal regulator output
3 − 5.5 V power supply (regulator input)
Active low reset pin.
This pin should be held ‘low’ for 10 mS from power stable
state. Recommended: 47 K resistor with 0.47 μF capacitor
STMPE1208S
Pin configuration and function
Figure 2.
STMPE1208S block diagram
S_Ref
Automatic
calibration unit
Data filtering unit
12-input
capacitive sensor
ID_0
S_In 0 - 11
ID_1
RESET
Host interface unit
G_INT
T_INT
SDAT
SCLK
BEEP
BEEP generator
12-bit
GPIO
Regulator
&
power control
Clock control unit
TCLK
GPIO 0 - 11
VPH
V REG
V25
CS00038
Application diagram
RESET
G_INT
T_INT
SDAT
STMPE1208S
SCLK
GPIO 0-11
Up to 12 touch pads
System host
Figure 3.
Up to 12 GPIO for system usage
7/51
Pin configuration and function
1.1
STMPE1208S
Power management
The STMPE1208S operates in 3 states.
Figure 4.
STMPE1208S operating states
RESET
ACTIVE
Host command
Time out
Touch or host
command
Host command
SLEEP
IDLE
CS00039
On RESET, the STMPE1208S enters the ACTIVE state immediately.
Upon a fixed period of inactivity, the device enters into the SLEEP state. Any touch activity in
SLEEP state would cause the device to go back to ACTIVE state.
In SLEEP mode:
-Calibration continues if F2A bit is set in CONTROL register
-Calibration stops if F2A bit is NOT set in CONTROL register
If no touch activity is expected, the host may set the device into HIBERNATE state to save
power.
8/51
STMPE1208S
2
Clock setting
Clock setting
The STMPE1208S uses a flexible clocking system that allows the user to adjust the clock
speed for optimization of power consumption.
Table 3.
Clocking system
Active
OSC
PDIV
Clock
Idle
NDIV
Sensor clock
00
01
0
20 KHz
100 Hz
1
10 KHz
50 Hz
0
10 KHz
50 Hz
1
5 KHz
25 Hz
0
5 KHz
25 Hz
1
2.5 KHz
12.5 Hz
0
2.5 KHz
12.5 Hz
1
1.25 KHz
6.25 Hz
1.6 MHz
800 KHz
1.6 MHz
10
11
400 KHz
200 KHz
The clock frequency must be set to value higher than the expected I2C frequency.
9/51
I2C interface
3
STMPE1208S
I2C interface
The features that are supported by the I2C interface are the following ones:
●
I2C slave device
●
Compliant to Philips I2C specification version 2.1
●
Supports standard (up to 100 kbps) and fast (up to 400 kbps) modes.
●
7-bit and 10-bit device addressing modes
●
General call
●
Start/Restart/Stop
The address is selected by the state of 2 pins. The state of the pins is read upon reset and
then the pins can be configured for normal operation. The pins have a pull-up or down to set
the address. The I2C interface module allows the connected host system to access the
registers in the STMPE1208S.
I2C addresses
Table 4.
7-bit address
ID_1
ID_0
7-bit address
Write
Read
0
0
0x58
0xB0
0xB1
0
1
0x59
0xB2
0xB3
1
0
0x5A
0xB4
0xB5
1
1
0x5B
0xB6
0xB7
Start condition
A Start condition is identified by a falling edge of SDATA while SCLK is stable at high state.
A Start condition must precede any data/command transfer. The device continuously
monitors for a Start condition and will not respond to any transaction unless one is
encountered.
Stop condition
A Stop condition is identified by a rising edge of SDATA while SCLK is stable at high state.
A Stop condition terminates communication between the slave device and bus master. A
read command that is followed by NoAck can be followed by a Stop condition to force the
slave device into idle mode. When the slave device is in idle mode, it is ready to receive the
next I2C transaction. A Stop condition at the end of a write command stops the write
operation to registers.
Acknowledge bit (ACK)
The acknowledge bit is used to indicate a successful byte transfer. The bus transmitter
releases the SDATA after sending eight bits of data. During the ninth bit, the receiver pulls
the SDATA low to acknowledge the receipt of the eight bits of data. The receiver may leave
the SDATA in high state if it would to not acknowledge the receipt of the data.
10/51
STMPE1208S
I2C interface
Data Input
The device samples the data input on SDATA on the rising edge of the SCLK. The SDATA
signal must be stable during the rising edge of SCLK and the SDATA signal must change
only when SCLK is driven low.
Slave device address
The slave device address is a 7 or 10-bit address, where the least significant 3-bit are
programmable. These 3-bit values will be loaded in once upon reset and after that these 3
pins no longer be needed with the exception during General Call. Up to 4 STMPE1208S
devices can be connected on a single I2C bus.
Memory addressing
For the bus master to communicate to the slave device, the bus master must initiate a Start
condition and followed by the slave device address. Accompanying the slave device
address, there is a Read/ bit (R/ ). The bit is set to 1 for read and 0 for write operation.
If a match occurs on the slave device address, the corresponding device gives an
acknowledgement on the SDA during the 9th bit time. If there is no match, it deselects itself
from the bus by not responding to the transaction.
Table 5.
Mode
Operation modes
Byte
Programming sequence
Start, Device address, R/W = 0, Register address to be read
Restart, Device address, R/W = 1, Data Read, STOP
Read
≥1
If no Stop is issued, the Data Read can be continuously performed. If
the register address falls within the range that allows an address autoincrement, then the register address auto-increments internally after
every byte of data being read. For those register addresses that fall
within a non-incremental address range, the address will be kept static
throughout the entire write operations. Refer to the memory map table
for the address ranges that are auto and non-increment. An example
of such a non-increment address is FIFO
Start, Device address, R/W = 0, Register address to be written, Data
Write, Stop
Write
≥1
If no Stop is issued, the Data Write can be continuously performed. If
the register address falls within the range that allows address autoincrement, then the register address auto-increments internally after
every byte of data being written in. For those register addresses that
fall within a non-incremental address range, the address will be kept
static throughout the entire write operations. Refer to the memory map
table for the address ranges that are auto and non-increment.
11/51
I2C interface
STMPE1208S
Slave
12/51
Data to
Write + 2
Ack
Stop
Ack
Data to
Write + 1
Stop
Data
Read + 2
No Ack
Data
Read + 1
Ack
Stop
No Ack
Data
Read
Ack
Ack
R/W=1
Ack
R/W=1
Data to
Write
Ack
Data
to be
written
Data
Read
Ack
Stop
Ack
Restart
Ack
Restart
Reg
Address
Device
Address
Ack
Reg
Address
Device
Address
Ack
Ack
R/W=0
Master
Ack
R/W=0
R/W=0
Device
Address
Reg
Address
Ack
Device
Address
Reg
Address
Ack
Device
Address
R/W=0
More than one byte
Read
Start
One byte
Write
Start
More than one byte
Read
Device
Address
Start
One byte
Read
Read and write modes (random and sequential)
Start
Figure 5.
STMPE1208S
4
Power schemes
Power schemes
The STMPE1208S can be powered by a 2.5 V supply directly, or 3.0 - 5.5 V supply through
the internal voltage regulator.
Figure 6.
Power using the internal regulator
3 - 5.5V
VPH
VREG
STMPE1208S
V25
2.2uF
GND
CS00041
1. REG_DISABLE bit in CTRL_2 register = 0
Figure 7.
Power bypassing the internal regulator
3 - 5.5V
VPH
VREG
NC
STMPE1208S
V25
2.25 - 2.75V
GND
CS00042
1. REG_DISABLE bit in CTRL_2 register = 1
13/51
Capacitive sensors
5
STMPE1208S
Capacitive sensors
The STMPE1208S capacitive sensor is based on fully digital, impedance change detection
engine that is capable of detecting very small change in capacitance.
Figure 8.
Touchkey
Capacitive sensors
7-bit impedance value
of each channel
Impedance sensor
Automatic calibration
Unit
Calibration control
parameters
5.1
Calibrated
impedance
Touched
keys
Data filtering
Data filtering control
Parameters
Capacitive sensing
The STMPE1208S senses a human touch by the additional capacitance introduced to the
pad (with respect to ground). This capacitance causes a delay in a clock signal on the
sensing pad, and the delay in the sensing pad is compared with a reference clock and the
difference is a direct representation of the additional capacitance introduced by the
proximity/touch of finger.
Figure 9.
14/51
Capacitive sensing
STMPE1208S
5.2
Capacitive sensors
Capacitance compensation
The STMPE1208S is capable to measuring up to 7.2 pF in capacitance difference between
the reference point (Zref) and the individual channels. In the case where the PCB
connection between the sensor pads and the device is too long, the "REFERENCE DELAY"
register is able to shift the reference by up to 6.0 pF, allowing the TOUCH channels to
measure added capacitance 7.2 pF with offset of 6.0 pF, as shown in following diagram.
In case this is still not enough to compensate for the capacitance on sensor lines (due to
very long sensor trace), an external capacitor of up to 30 pF can be connected at the A_Ref
pin. This allows to further shift up the dynamic range of the capacitance measurement.
Figure 10. Capacitance compensation
Reference delay register = 0
Dynamic range = 0 - 7.2 pF
7.2 pF
6.0 pF
6.0 pF
7.2 pF
Reference delay register = 6.0 pF
Dynamic range = 6.0 - 13.2 pF
30.0pF
7.2 pF
Reference delay = 6.0 pF
S_REF external capacitance = 30 pF
Dynamic range = 36 - 43.2 pF
Increasing capacitance
CS00043
The sensed capacitance is accessible to host through the "IMPEDANCE" registers.
5.3
Setting of TVR and EVR
The STMPE1208S uses 2 main parameters to control the sensitivity and calibration of the
capacitive sensing system. TVR (touch variance) is a channel-specific value, that specifies
the number of steps the sensed capacitance must be above the internal reference, to be
considered a touch. Generally, this should be set as 4 −10, but it must be bigger than EVR.
The EVR (environment variance) is a shared value that is applied to all the channels. This
specifies the maximum change in capacitance that can be considered due to the shifting of
the environmental factor. Generally, this should be set to 1 −5, but it must be less than TVR.
Environment tracking calibration
On power up, a calibration is executed. The initial calibration takes about 150 clock cycles of
sensor clock for completion. Using 5 kHz sensor clock, this would be 30 mS.
However, if any of the sensors are touched during powering up, calibration is delayed, until
all sensors are untouched. In this case, the time taken for calibration, from the time when all
sensors are untouched is:
2 * calibration interval + 150 * sensor clock period
15/51
Capacitive sensors
STMPE1208S
The STMPE1208S maintains 2 parameters for each TOUCH channels: TVR and
CALIBRATED IMPEDANCE. CALIBRATED IMPEDANCE is an internal reference of which, if
the currently measured IMPEDANCE exceeds the CALIBRATED IMPEDANCE by a
magnitude of TVR, it is considered a TOUCH.
If the IMPEDANCE is more than the CALIBRATED IMPEDANCE, but the magnitude does
not exceed CALIBRATED IMPEDANCE by TVR, it is not considered a TOUCH. In this case,
2 scenarios are possible:
1. Environmental changes has caused the IMPEDANCE to increase
2. Finger is near the sensing pad, but not near enough
In case 1, the change in IMPEDANCE is expected to be small, as environmental changes
are normally gradual. A value "EVR" is maintained to specify the maximum IMPEDANCE
change that is still considered an environmental change.
Table 6.
Calibration action under different scenarios
Scenario
Touch sensing and calibration action
IMP>CALIBRATED IMP + TVR
TOUCH,
no calibration
IMP>CALIBRATED IMP + EVR
NO TOUCH,
no calibration
IMP<CALIBRATED IMP + TVR
IMP<CALIBRATED IMP + EVR
NO TOUCH,
new CALIBRATED IMP = previous
IMP>CALIBRATED IMP
CALIBRATED IMP + change in IMP
IMP<CALIBRATED IMP
NO TOUCH,
new CALIBRATED IMP = new IMP
ETC WAIT register state a period of time of which, all TOUCH inputs must remain "NO
TOUCH" for the next calibration to be carried out.
CAL INTERVAL states the period of time between successive calibrations when there are
prolonged NO TOUCH condition.
5.3.1
3-stage data filtering system
The output from the calibration unit is an instantaneous "TOUCH" or "NO TOUCH" status.
This output is directed to the filtering stage where the 2 stage noise filtering and 1 stage
data filtering is applied to the touch status.
16/51
STMPE1208S
Capacitive sensors
Figure 11. 3-stage data filtering system
Touch/No-touch from
calibration unit
Integration
unit
Integration period
Integration threshold
Filter
unit
Filter period
Filter threshold
AFS
unit
Touch byte
AFS mode
CS00044
Integration and filtering unit
TOUCH is sampled across a programmable period of time. The output of the integration
stage would be a "STRENGTH" (in STRENGTH register) that indicates the number of times
a "TOUCH" is seen, across the integration period. The "STRENGTH" is then compared with
the value in "STRENGTH THRESHOLD" register. If STRENGTH exceeds the STRENGTH
THRESHOLD, this is considered a valid TOUCH.
If required, a 2nd stage filtering feature controlled by FILTER_ PERIOD and
FILTER_THRESHOLD registers.
In data filtering stage, 3 modes of operation are supported:
AFS Mode 1: Only the TOUCH channel with highest STRENGTH is taken
AFS Mode 2: All TOUCH channels with STRENGTH > STRENGTH THRESHOLD is taken
AFS Mode 3: The 2 TOUCH channels with the highest STRENGTH are selected.
These modes are selected using the FEATURE SELECTOR register.
The final, filtered data is accessible through the TOUCH_BYTE register.
5.3.2
Noise filtering
When the STMPE1208S is operating in the vicinity of highly emissive circuits (DC-DC
Converter, PWM Controller/Drive etc), the sensor inputs will be affected by high-frequency
noise. In this situation, the 2-stage time-integrating function could be used to distinguish
between real touch, or emission-related false touch.
5.3.3
BEEP output
STMPE1208S is able to drive an external Piezo Buzzer directly with the built-in beep
generator. The BEEP output can be programmed to varies from 1.5 KHz to 400 KHz, with
period of 100 uS to 2.5 S.
17/51
Capacitive sensors
5.3.4
STMPE1208S
Interrupt system
2 interrupt pins are available in STMPE1208S for different application needs.
–
G_INT asserts when there are any unmasked interrupt events
–
T_INT asserts when there are any TOUCH events
Figure 12. Interrupt system
End of calibration
EINT
EINT
enable
GPIO
0-7
INT
INT
pending
mask
G_INT
Idle to active
Active to idle
TOUCH
T_INT
1. G_INT is cleared by writing to the INT CLEAR register
2. T_INT is cleared by reading the Touch Byte register
18/51
STMPE1208S
6
Register map and function description
Register map and function description
This section lists and describes the registers of the STMPE1208S device, starting with a
register map and then detailed descriptions of register types.
Table 7.
Address
0x00
Register summary map table
Module register
FEATURE_SEL
0x01 −0x0C TVR 0 −11
Type
Reset value
Description
R/W
0x04
Feature selection
R/W
0x08
TVR (touch variance) setting of
each capacitive channel
0x0D
EVR
R/W
0x04
EVR (enviromental variance)
setting of all 12 channels
0x0E
ETC_WAIT
R/W
0x27
Wait time for calibration
0x0F
REF_DELAY
R/W
0x00
Value of reference delay chain
R/W
0x01
Setting of strength threshold for
each channel
0x10 − 0x1B STRENGTH_THRES
0x1C
INTEGRATION_ TIME
R/W
0x0F
Integration time for AFS mode
0x1D
IDLE_TIME
R/W
0x0F
Period to enter IDLE mode after
non-activity
0x1E
GPIO_REG_L
R/W
0x00
Output state of I/O if configured
as GPIO
0x1F
GPIO_REG_H
R/W
0x00
Output state of I/O if configured
as GPIO
0x20
GPIO_CFG_L
R/W
0x00
To configure I/O as GPIO or
direct capacitive measurement
output
0x21
GPIO_CFG_H
R/W
0x00
To configure I/O as GPIO or
direct capacitive measurement
output
0x22
GPIO_DIR_L
R/W
0x00
Direction of GPIO
0x23
GPIO_DIR_H
R/W
0x00
Direction of GPIO
0x24
CTRL_1
R/W
0x00
Functional control of capacitive
sensing
0x25
CTRL_2
R/W
0x00
Functional control of capacitive
sensing
0x26
INT_MASK
R/W
0x00
Mask for GINT interrupt
sources
0x27
INT_CLR
R/W
0x00
Writing this register clears the
INT Pending register
0x28
BEEP_PER
R/W
0x00
Set the period of BEEP output
0x29
BEEP_FREQ
R/W
0x00
Set the frequency of BEEP
output
19/51
Register map and function description
Table 7.
Address
20/51
STMPE1208S
Register summary map table (continued)
Module register
Type
Reset value
Description
0x2A
CAL_INTERVAL
R/W
0x30
Set the interval between
calibrations
0x2B
EXT_INT_EN
R/W
0x00
Enable for GPIO interrupt
0x2C
EXT_INT_POL
R/W
0x00
Polarity of GPIO interrupt
0x2D
FILTER_PERIOD
R/W
0x00
Set the period for filter feature
0x2E
FILTER_TRES
R/W
0x00
Set the threshold of filter
feature
0x50 −0x5B STRENGHT
R
0x00
Strength recorded during each
integration period in AFS mode
0x5C −0x67 CAL_IMP
R
0x00
Reference impedance of each
channel after ETC calibration
0x68 −0x73 IMP
R
0x00
Measured impedance of each
channel
0x74
STA
R
0x00
Power management mode
0x75
TOUCH_BYTE_L
R
0x00
Touch sensing data output
0x76
TOUCH_BYTE_H
R
0x00
Touch sensing data output
0x77
INT_PENDING
R
0x00
Status of GINT interrupt
sources
0x78
GPIO_IN_L
R
0x00
GPIO input states can be read
here
0x79
GPIO_IN_H
R
0x00
GPIO input states can be read
here
0xF8
CLK_SRC_INTERN
W
−
0xF9
CLK_SRC_EXT
W
−
0xFA
BIAS_OFF
W
−
0xFB
BIAS_ON
W
−
0xFC
WAKEUP_SLEEP
W
−
0xFD
ENTER_SLEEP
W
−
0xFE
COLD_RST
W
−
0xFF
WARM_RST
W
−
STMPE1208S
Register map and function description
FEATURE_SEL
7
6
Feature selection register
5
4
RESERVED
3
2
1
0
AFS3
AFS2
AFS1
FILTER_EN
Address:
0x00
Type:
R/W
Reset:
0x04
Description:
The feature selection register is used to select the AFS mode and filter enable
[7:4] RESERVED
[3] AFS3: write '1' to enable AFS mode 3 (two strongest keys only)
[2] AFS2: write '1' to enable AFS mode 2 (all keys above threshold)
[1] AFS1: write '1' to enable AFS mode 1 (one strongest key only)
[0] FILTER_EN: write '1' to enable filter feature
Note: only one bit among AFS1, AFS2, AFS3 could be set to '1' at the same time. If more than
one are set to '1', results of the operation would be unpredictable.
TVR
7
Touch variance register [0-11]
6
5
4
3
-
2
1
0
TVR [6:0]
Address:
0x01 - 0x0C
Type:
R/W
Reset:
0x08
Description:
Setting the TVR between 0 - 99
A high TVR value decreases the sensitivity of the sensor, but increasing its tolerance
to ambient noise. A small TVR value increases the sensitivity.
Each step of TVR is equivalent to a capacitance of 60 fF
Recommended value to TVR is 4-8.
[7] RESERVED
[6:0] TVR [6:0]
21/51
Register map and function description
EVR
7
STMPE1208S
Enviromental variance register
6
5
4
3
-
2
1
0
EVR [6:0]
Address:
0x0D
Type:
R/W
Reset:
0x04
Description:
EVR is used to detect "Non-Touch" condition. Each step of EVR is equivalent to a
capacitance of 60 fF. Recommended value to EVR is 2-6 (EVR must always be
smaller than TVR).
[7] RESERVED
[6:0] EVR [6:0]
ETC_WAIT
7
Enviromental tracking calibration wait time
6
5
4
3
2
1
0
ETC_WAIT [7:0]
Address:
0x0E
Type:
R/W
Reset:
0x27
Description:
Wait time for ETC operation, from the first instance of all 12 keys returning to no-touch
status. ETC wait time = ETC_Wait[7:0] *64 *clock period. A "non-touch" condition
must persist for this wait time, before an ETC operation is carried out.
[7:0] ETC_WAIT [7:0]
22/51
STMPE1208S
Register map and function description
REFERENCE_DELAY
7
6
Reference delay
5
RESERVED
4
3
2
1
0
REFERENCE_DELAY
Address:
0x0F
Type:
R/W
Reset:
0x00
Description:
Reference delay register. Valid range = 0-128. Each step represents capacitance
value of 60 pF. Warm reset is required after this value is updated.
[7] RESERVED
[6:0] REFERENCE_DELAY:
Valid range = 0-127
Each step represents capacitance value of 0.06 pF
Warm reset is required after this value is updated
23/51
Register map and function description
STRENGTH_THRES
7
6
STMPE1208S
Strength threshold
5
4
3
2
1
0
STRENGTH_THRESHOLD
Address:
0x10 - 0x1B
Type:
R/W
Reset:
0x01
Description:
Setting threshold to be used in AFS mode to determin a valid touch.
[7:0] STRENGTH_THRESHOLD
INTEGRATION_TIME
7
6
Integration time register
5
4
3
2
1
0
INTEGRATION_TIME
Address:
0x1C
Type:
R/W
Reset:
0x0F
Description:
Integration time in AFS mode.
[7:0] INTEGRATION_TIME:
Total period of integration = sensor clock period * integration time [7:0]
IDLE_TIME
7
Idle time register
6
5
4
3
2
1
0
IDLE_TIME
Address:
0x1D
Type:
R/W
Buffer:
Reset:
0x0F
Applicability:
Description:
The device enters in idle state if there is not touch detected for a period equal to idle
time [7:0] * 5000 * clock_sensor_period.
[7:0] IDLE_TIME
24/51
STMPE1208S
Register map and function description
GPIO_STA_L
GPIO state register L
7
6
5
4
3
2
1
0
IO-7
IO-6
IO-5
IO-4
IO-3
IO-2
IO-1
IO-0
Address:
0x1E
Type:
R/W
Reset:
0x00
Description:
If a DIO is set to function as GPIO (GPIO_CFG register) and output (GPIO_DIR
register), the bits in this register would determine the output value of the
corresponding GPIO. Applicable for GPIOs 0 - 7.
GPIO_STA_H
7
GPIO state register H
6
5
4
RESERVED
3
2
1
0
IO-11
IO-10
IO-9
IO-8
Address:
0x1F
Type:
R/W
Reset:
0x00
Description:
If a DIO is set to function as GPIO (GPIO_CFG register) and output (GPIO_DIR
register), the bits in this register would determine the output value of the
corresponding GPIO. Applicable for GPIOs 8 - 11.
GPIO_CFG_L
GPIO configuration register
7
6
5
4
3
2
1
0
IO-7
IO-6
IO-5
IO-4
IO-3
IO-2
IO-1
IO-0
Address:
0x20
Type:
R/W
Reset:
0x00
Description:
Writing ‘1’ in this GPIO configuration register sets the corresponding DIO as GPIO.
Applicable for GPIOs 0-7.
GPIO_CFG_H
7
GPIO configuration register
6
5
RESERVED
4
3
2
1
0
IO-11
IO-10
IO-9
IO-8
Address:
0x21
Type:
R/W
Reset:
0x00
Description:
Writing ‘1’ in this GPIO configuration register sets the corresponding DIO as GPIO.
Applicable for GPIOs 8-11.
25/51
Register map and function description
GPIO_DIR_L
STMPE1208S
GPIO direction register
7
6
5
4
3
2
1
0
IO-7
IO-6
IO-5
IO-4
IO-3
IO-2
IO-1
IO-0
Address:
0x22
Type:
R/W
Reset:
0x00
Description:
Writing '1' in this register sets the corresponding GPIO as input. Writing '0' in this
register sets the corresponding GPIO as output. Applicable for GPIOs 0-7.
GPIO_DIR_H
7
GPIO direction register
6
5
RESERVED
4
3
2
1
0
IO-11
IO-10
IO-9
IO-8
Address:
0x23
Type:
R/W
Reset:
0x00
Description:
Writing '1' in this register sets the corresponding GPIO as input. Writing '0' in this
register sets the corresponding GPIO as output. Applicable for GPIOs 8-11.
26/51
STMPE1208S
Register map and function description
CTRL_1
Control register 1
7
6
-
F2A
5
4
PDIV[1:0]
Address:
0x24
Type:
R/W
Reset:
0x00
Description:
Control register.
3
2
1
0
NDIV
HDC_U
HDC_C
HOLD_C
[7] RESERVED
[6] F2A:
Write '1' to force the device to stay in active mode at all times. For best performance and
stability, this bit must be set to ‘1’ at all times.
[5:4] PDIV[1:0]:
'00' : System clock = 1.6MHz
'01' : System clock = 800KHz
'10' : System clock = 400KHz
'11' : System clock = 200KHz
[3] NDIV:
Sensor clock frequency setting:
'0' :sensor clock = system clock / 80
'1' :sensor clock = system clock / 160
Initial calibration time = sensor clock * 150
[2] HDC_U:
Unconditional host driven calibration. Executes an unconditional calibration. This is valid only if
"Hold C" bit is set, and device in Active mode. Reads '0' when calibration is completed.
[1] HDC_C:
Conditional host driven calibration. Executes a calibration if no touch is being sensed.
[0] HOLD_C:
'0' for auto-calibration mode
'1' disables auto-calibration
27/51
Register map and function description
CTRL_2
7
STMPE1208S
Control register 2
6
5
4
RESERVED
Address:
0x25
Type:
R/W
Reset:
0x00
Description:
Control register.
3
2
1
0
REGD
SCD
BEEP_ON
INT_POL
[7:4] RESERVED
[3] REGD:
'0' to enable internal regulator (default)
'1' to disable
[2] SCD: Sensor clock disable.
Write '1' to disable sensor clock.
[1] BEEP_EN:
'1' to enable beep output
[0] INT_POL: Interrupt polarity
'0' for rising edge
'1' for falling edge
28/51
STMPE1208S
Register map and function description
INT_MASK
Interrupt mask
7
6
5
-
EOC
EINT
4
3
-
2
1
0
I2A
A2I
TOUCH
Address:
0x26
Type:
R/W
Reset:
0x08
Description:
Writing '1' to this register disables the corresponding interrupt source.
[7] RESERVED
[6] EOC:
End of calibration.
[5] EINT:
EINT interrupt sources (GPIO input) changes.
[4:3] RESERVED
[2] I2A:
SLEEP to active transition
[1] A2I:
Active to idle transition
[0] TOUCH:
Touch detect.
29/51
Register map and function description
INT_CLR
STMPE1208S
Interrupt clear register
7
6
5
-
EOC
EINT
Address:
4
3
-
2
1
0
I2A
A2I
TOUCH
0x27
Type:
Reset:
0x00
Description:
If the corresponding bit in the INT_PENDING register is set, system software must
write '1' to this register to clear the bits in INT_PENDING register.
[7] RESERVED
[6] EOC:
End of calibration.
[5] EINT:
EINT interrupt sources (GPIO input) changes.
[4:3] RESERVED
[2] I2A:
SLEEP to active transition
[1] A2I:
Active to idle transition
[0] TOUCH:
Touch detect.
BEEP_PERIOD
7
6
Beep period
5
4
3
2
BEEP_PERIOD [7:0]
Address:
0x28
Type:
R/W
Reset:
0x00
Description:
Beep period
[7:0] BEEP_PERIOD:
Period = Beep Period [7:0] * 8* System Clock Period
System Clock Period = 0.625 μs (1.6 MHz) to 5 μs (200 KHz)
Period of Beep (min) = 0.625 μs * 8* 1 = 5 μs
Period of Beep (max) = 5 μs * 8* 255 = 10 ms
30/51
1
0
STMPE1208S
Register map and function description
BEEP_FREQUENCY
7
6
Beep frequency
5
4
3
2
1
0
BEEP_FREQUENCY[7:0]
Address:
0x29
Type:
R/W
Reset:
0x00
Description:
Beep frequency in KHz = system clock/(beep frequency [7:0]*2)+2)
[7:0] BEEP_FREQUENCY:
Min Freq = 200 KHz/512 = 390 Hz
Max Freq = 1.6 MHz/2 = 800 kHz
CAL_INTERVAL
7
6
Calibration interval
5
4
3
2
1
0
INTERVAL[7:0]
Address:
0x2A
Type:
R/W
Reset:
0x30
Description:
Calibration interval
[7:0] INTERVAL:
Interval between calibration = Calibration Interval [7:0] * sensor clock period * 50
31/51
Register map and function description
EXT_INT_EN
STMPE1208S
External interrupt enable register
7
6
5
4
3
2
1
0
IO-7
IO-6
IO-5
IO-4
IO-3
IO-2
IO-1
IO-0
Address:
0x2B
Type:
R/W
Reset:
0x00
Description:
Enable of the GPIO interrupt.
‘1’ enables the corresponding GPIO to generate an interrupt on detecting change in
its input. Only GPIO 0-7 is able to generate interrupts.
EXT_INT_POL
External interrupt polarity register
7
6
5
4
3
2
1
0
IO-7
IO-6
IO-5
IO-4
IO-3
IO-2
IO-1
IO-0
Address:
0x2B
Type:
R/W
Reset:
0x00
Description:
Polarity of GPIO interrupt.
‘0’ positive edge on external interrupt input sets GINT.
‘1’ negative edge on external interrupt input sets GINT.
32/51
STMPE1208S
Register map and function description
FILTER_PERIOD
7
6
Filter period
5
4
3
2
1
0
FILTER_PERIOD[7:0]
Address:
0x2D
Type:
R/W
Reset:
0x00
Description:
Filter period.
[7:0] FILTER_COUNT:
Additional filter to stabilize touch output in AFS mode.
AFS touch output is monitored for filter period [7:0] times every integration time. For each time
a "touch status" is detected, an internal "Filter Counter" is incremented once. This counter
value is then compared with Filter Threshold (register 0x3E).
33/51
Register map and function description
FILTER_THRESHOLD
7
6
STMPE1208S
Filter threshold
5
4
3
2
1
0
FILTER_THRESHOLD
Address:
0x2E
Type:
R/W
Reset:
0x00
Description:
Filter threshold.
[7:0] FILTER_THRESHOLD:
An internal "Filter counter" is compared with Filter Threshold [7:0] to determine if a valid touch
has occurred.
Note: I2C writes to this register will not be acknowledged. However as long as I2C timing is
followed, the writing to this register will work correctly.
STRENGTH
7
Strength
6
5
4
3
2
1
0
STRENGTH
Address:
0x50 - 5B
Type:
R
Reset:
0x00
Description:
Counts the number of times a sensed impedance exceeds calibrated reference
impedance over and integration time. Maximum strength equals integration time [7:0]
[7:0] STRENGTH:
Read-only field.
34/51
STMPE1208S
Register map and function description
CALIBRATED_IMPEDANCE
7
6
Calibrated impedance
5
4
3
2
1
0
1
0
CAL_IMPEDANCE
Address:
0x5C - 0x67
Type:
R
Reset:
0x00
Description:
Calibrated reference impedance = 128 - CAL.Impedance[7:0].
[7:0] CALIBRATED IMPEDANCE:
Calibrated reference impedance.
IMPEDANCE
7
Impedance
6
5
4
3
2
IMPEDANCE
Address:
0x68 - 0x73
Type:
R
Reset:
0x00
Description:
Impedance is the instantaneous impedance value seen at the input pin of each cap.
sensing pin.
[7:0] IMPEDANCE:
Currently sensed impedance
35/51
Register map and function description
STATUS
STMPE1208S
Status register
7
6
5
4
3
2
1
RESERVED
Address:
0x74
Type:
R
Reset:
0x00
0
IDLE
Applicability:
Description:
IDLE: Reads '1' if device is currently in IDLE mode, reads '0' if device is not in IDLE
mode
[7:6] RESERVED
[0] IDLE:
Currently sensed impedance
TOUCH_BYTE_L
Touch byte L
7
6
5
4
3
2
1
0
CH7
CH6
CH5
CH4
CH3
CH2
CH1
CH0
Address:
0x75
Type:
R
Reset:
0x00
Description:
CH n: Reads the touch status of channel n (n=0-7). If the key is touched (Impedance
> Calibrated Impedance + TVR), the corresponding bit in this register will read '1'.
Reading TOUCH_BYTE_L and TOUCH_BYTE_H will clear the TINT assertion.
36/51
STMPE1208S
Register map and function description
TOUCH_BYTE_H
7
6
Touch byte H
5
RESERVED
4
3
2
1
0
CH11
CH10
CH9
CH8
Address:
0x76
Type:
R
Reset:
0x00
Description:
CH n: Reads the touch status of channel n (n=8-11). If the key is touched (Impedance
> Calibrated Impedance + TVR), the corresponding bit in this register will read '1'.
Reading TOUCH_BYTE_L and TOUCH_BYTE_H will clear the TINT assertion.
[7:4]
RESERVED
[3] CH11:
[2] CH10:
[1] CH9:
[0] CH8:
37/51
Register map and function description
INT_PENDING
7
STMPE1208S
Interrupt pending
6
5
4
RESERVED
3
2
1
0
EOC
I2A
A21
TOUCH
Address:
0x77
Type:
R
Reset:
0x00
Description:
This register reflects the status of various possible interrupt sources. Upon the
occurrence of an event, the corresponding bit in this register will be set to '1' by the
hardware.
[7:4] RESERVED
[3] EOC:
End of calibration
[2] I2A:
SLEEP to active transition
[1] A21:
Active to SLEEP transition
[0] TOUCH:
Touch detect
GPIO_IN_L
GPIO input state (lower) register
Address:
0x79
Type:
R
Reset:
0x0
Description:
Reads the current logical level of corresponding DIO if it is set as GPIO input.
38/51
STMPE1208S
Register map and function description
GPIO_IN_H
GPIO input state (higher) register
Address:
0x7A
Type:
R
Reset:
0x00
Description:
Reads the current logical level of corresponding DIO if it is set as GPIO input.
39/51
Command registers
7
STMPE1208S
Command registers
The command registers do not have a data field. The device carries out a predetermined
operation upon receiving a write access to these address offset. However, a dummy dataphase is used to complete the I2C transaction.
Table 8.
Command registers
Command
0xF8 CLK_SRC_INTERNAL
Use internal OSC as clock source
0xF9 CLK_SRC_EXTERNAL
Use TCLK pin as clock source
0xFA BIAS_OFF
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Operation
Turns OFF biasing for internal LDO
When external supply is used for V25, turning
OFF the biasing for internal LDO reduces current
consumption
0xFB BIAS_ON
Turns ON biasing for internal LDO
0xFC Wake Up
Exits from sleep and enters Active mode
0xFD Enter Sleep
Enter sleep mode
0xFE Cold Reset
Resets all states and registers
0xFF Warm Reset
Resets internal state machines, register values
remain the same
NOTE: I2C WRITE TO THIS REGISTER WILL
NOT BE ACKNOWLEDGED. However as long as
I2C timing is followed, the writing to this register
will work correctly
STMPE1208S
Command registers
Figure 13. Software interface (G_INT based)
Initialization
GPIO configuration, direction and output
Calibration interval
ETC wait
Feature select
EVR setting
EVR setting
Integration time
TVR setting
Integration treshold setting
Control 1, control 2
Wait for interrupt
Interrupt service routine
Read interrupt pending register
Write interrupt mask (to mask all)
Write interrupt clear register
Read “touch” byte register
Read calibrated impedance registers
Write interrupt mask (To unmask all)
Post processing
(optional)
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Command registers
STMPE1208S
Figure 14. Software interface (T_INT based)
Initialization
GPIO configuration, direction and output
Calibration interval
ETC wait
Feature select
EVR setting
EVR setting
Integration time
TVR setting
Integration treshold setting
Control 1, control 2
Wait for interrupt
Interrupt service routine
Read touch byte register
Post processing
(optional)
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STMPE1208S
8
Maximum rating
Maximum rating
Stressing the device above the rating listed in the “Absolute maximum ratings” table may
cause permanent damage to the device. These are stress ratings only, and operation of the
device at these or any other conditions above those indicated in the operating sections of
this specification is not implied. Exposure to absolute maximum rating conditions for
extended periods may affect device reliability. Refer also to the STMicroelectronics SURE
Program and other relevant quality documents.
Table 9.
Absolute maximum ratings
Value
Symbol
Parameter
Unit
Min
Max
Vph
Power supply
2.5
5.5
V
V25
Power supply
2.25
2.75
V
VIN
Digital input
-0.3
VPH +0.3
V
TJ
Operating temperature
-40
85
°C
TS
Storage temperature
-55
95
°C
ESD
8.1
Typ
HBM on capacitive sensor pins
7
kV
Recommended operating conditions
Table 10.
Recommended operating conditions
Value
Symbol
Parameter
Unit
Min
Vph
Power supply
3.0
V33
Power supply
2.25
Operating temperature
-40
TJ
Typ
Max
5.5
V
2.5
2.75
V
25
85
°C
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Electrical specifications
9
STMPE1208S
Electrical specifications
Table 11.
DC electrical characteristics (-40 −85 ° C unless otherwise stated))
Value
Symbol
Parameter
Test condition
Unit
Min
Iout
Iactive
Iidle
Isleep
Vout = 0.75*VPH
Active current
Touch present
Idle current
Sleep current
Max
2
mA
98
160
μA
No-touch
60
80
μA
Sleep mode
0.1
1
μA
1.0
V
VIL
Digital input low
VIH
Digital input high
VOL
Digital output low
VOH
Digital output high
Iout
GPIO drive current
Iin
GPIO sink current
Total sink current on
all GPIOs 〈 80 mA
Input leakage
VIN = 5.5 V
VPH = 5.5 V
Ileakage
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GPIO driving current
Typ
0.7Vph
V
1.0
Vph-0.5
V
V
0.2
2
mA
10
mA
2
μA
STMPE1208S
10
Package mechanical data
Package mechanical data
In order to meet environmental requirements, ST offers these devices in ECOPACK®
packages. These packages have a lead-free second level interconnect. The category of
second level interconnect is marked on the package and on the inner box label, in
compliance with JEDEC Standard JESD97. The maximum ratings related to soldering
conditions are also marked on the inner box label. ECOPACK is an ST trademark.
ECOPACK specifications are available at: www.st.com.
Table 12.
QFN40 (5 x 5 mm) mechanical data
millimeters
Symbol
Min
Typ
Max
A
0.80
0.85
0.90
A1
0.00
A3
b
0.05
0.203 ref
0.15
0.20
D
5.00 BSC
E
5.00 BSC
0.25
D2
3.70
3.80
3.90
E2
3.70
3.80
3.90
e
L
0.40 BSC
0.30
0.35
L1
0.40
0.10
P
45° BSC
aaa
0.15
ccc
0.10
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Package mechanical data
STMPE1208S
Figure 15. QFN40 (5 x 5 mm) package outline
8072802_A
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STMPE1208S
Package mechanical data
Figure 16. QFN40 recommended footprint without ground pad VIA
Figure 17. QFN40 recommended footprint with ground pad VIA
0.68
0.30
0.68
1.27
1.27
Via
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Package mechanical data
Figure 18. QFN40 tape information
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STMPE1208S
STMPE1208S
Package mechanical data
Figure 19. Reel information
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Revision history
11
STMPE1208S
Revision history
Table 13.
Document revision history
Date
Revision
14-Feb-2008
1
Initial release.
2
Modified title in cover page and ETC_WAIT register description.
Updated: Table 5: Operation modes on page 11
Added Figure 16: QFN40 recommended footprint without ground pad
VIA on page 47.
3
Document status promoted from preliminary data to datasheet.
Modified: BEEP_PERIOD and BEEP_FREQUENCY registers
description, HBM ESD protection value, Table 2: Pin assignments
and description on page 5 and Chapter 10: Package mechanical
data on page 45.
Updated: Section 8: Maximum rating on page 43 and Section 9:
Electrical specifications on page 44.
04-Jun-2008
18-Jul-2008
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Changes
STMPE1208S
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