STMPE812ABJR STMicroelectronics, STMPE812ABJR Datasheet - Page 31

• Manufacturer Part Number: STMPE812ABJR
• Description: Touch Screen Converters & Controllers Touchscreen cntrlr S-Touch
• Manufacturer: STMicroelectronics
• Type: Resistive Touch Controllersr

Specifications of STMPE812ABJR

• Rohs: yes
• Input Type: 1 TSC
• Data Rate: 400 kbps
• Resolution: 12 bit
• Interface Type: 4-wire, I2C
• Supply Voltage: 1.65 V to 3.6 V
• Supply Current: 100 uA
• Operating Temperature: - 40 C to + 85 C
• Package / Case: CSP-12
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Supply Voltage - Max: 3.6 V
• Supply Voltage - Min: 1.65 V

STMPE812A
11
Touchscreen controller
The STMPE812A is integrated with a hard-wired touchscreen controller for 4-wire resistive
type touchscreen. The touchscreen controller is able to operate completely autonomously,
and would interrupt the connected CPU only when pre-defined event occurs.
The TSC is based on an internal 20Ksamples/sec ADC, running off a 1 MHz (minimum
880 kHz) RC OSC.
Sampling time = touch detect delay*2 + (settling time + (ADC conversion time*MAV) ) *3
Table 11.
Figure 8.
880 kHz
880 kHz
880 kHz
Oscillator speed
Sampling time/frequency calculation
Touchscreen controller internal RC OSC connection
conversion
50 µs
50 µs
50 µs
ADC
time
Doc ID 18225 Rev 4
640 µs
Touch
detect
delay
40 µs
40 µs
Settling
640 µs
40 µs
40 µs
time
average
Median
None
10-2
20-4
40*2 + 3*(40+(50*1)) = 350 µs
(2.8K sample sets/sec)
40*2 + 3*(40+
(50*10))=1700 µs (588 sample
sets/sec)
640*2 + 3*(640+ (50*20))
=6200 µs (161 sample
sets/sec)
(complete X/Y/Z sample
Touchscreen controller
Sampling time/freq
sets)
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