SX8661I07AULTRT Semtech, SX8661I07AULTRT Datasheet - Page 21

• Manufacturer Part Number: SX8661I07AULTRT
• Description: IC, Capacitive Button Touch And Proximity Controller, 8 SENSOR, MLPQ-28
• Manufacturer: Semtech

Specifications of SX8661I07AULTRT

• Controller Type: Capacitive Touch Screen
• Ic Interface Type: I2C
• Supply Voltage Range: 2.7V To 3.6V
• Operating Temperature Range: -40°C To +85°C

SX8661
Low Power, Capacitive Button Touch and Proximity Controller
(8 sensors) with LED Drivers and Analog Output
ADVANCED COMMUNICATIONS & SENSING
DATASHEET
In the Strongest-mode the strongest touched button will be reported on the AOI and the I2C. All touches that
occur afterwards representing a weaker touch will not be reported. Only a touch which is stronger will be reported
by the SX860.
Figure 16 shows the Strongest-mode reporting in case of 2 touches (with bt1 the strongest touch).
Strongest-mode reporting with 2 touches
Figure 16
At time t1 button0 is touched and reported on the AOI. At time t2 button1 is touched as well. As bt1 is the
strongest touch it will be reported on the AOI immediately (or after one scan period at idle level). At time t3 the
button0 is released while the AOI continues to report button1. At time t4 both buttons are released and the AOI
reports the idle level.
In some special cases (when the buzzer is suspected to load heavily the power supply) the user may choose the
AOI to go to 0V, to VDD or to the AOI idle level for the duration the buzzer is active.
AOI behavior with 0V buzzer state
Figure 17
In Figure 17 the AOI will go to 0V each time the buzzer is active. The AOI returns then to either the idle mode for
one scan period or goes immediately to the PWM button level.
In case the SX8661 is set to sleep mode the AOIs will go to 0V.
3.9 Analog Sensing Interface
The Analog Sensing Interface (ASI) converts the charge on the sensors into ticks which will be further digitally
processed. The basic principle of the ASI will be explained in this section.
The ASI consists of a multiplexer selecting the sensor, analog switches, a reference voltage, an ADC sigma delta
converter, an offset compensation DAC and an external integration capacitor (see Figure 18).
Revision v3.2, January 2011
© 2011 Semtech Corp.
www.semtech.com
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