DM160220 datasheet(5/20 Pages) MICROCHIP

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 2012-2013 Microchip Technology Inc.

Preliminary

DS40001664B-page 5

MTCH101

3.0

SENSITIVITY ADJUSTMENT

The sensitivity of the system determines how far and

fast it can respond to proximity or touch. The MTCH101

provides the MTSA pin to adjust the sensitivity, and the

voltage on this pin will determine the sensitivity. VDD

voltage will give the lowest sensitivity, while GND

voltage will give the highest sensitivity.

The device will sample the voltage on the MTSA pin

after each scan, so it does not only support setting a

fixed sensitivity by a resistor ladder, but it also allows

adjusting the sensitivity dynamically, while the device is

running.

Digital-to-Analog

Converter

(DAC)

controlled by the host, or a hardware potentiometer can

be used to adjust the sensitivity. See typical circuit in

Figure 3-1 to Figure 3-4.

FIGURE 3-1:

FIXED SENSITIVITY

USING RESISTOR

LADDER

FIGURE 3-2:

HARDWARE SENSITIVITY

ADJUST USING

POTENTIOMETER

FIGURE 3-3:

SENSITIVITY

CONTROLLED BY HOST

USING DAC

FIGURE 3-4:

SENSITIVITY

CONTROLLED BY HOST

USING PWM

MTSA

VDD

10k

Note: Both R1 and R2 are recommended to be

greater than 100K for lower power consumption.

MTSA

VDD

10k

Note 1:

Application Note AN538, “Using PWM to

Generate Analog Output”

has details

about how to choose appropriate R and C

values.

MTSA

10k

Host

DAC

MTSA

Host

PWM

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