MPR031EP Freescale Semiconductor, MPR031EP Datasheet - Page 8

• Manufacturer Part Number: MPR031EP
• Description: Capacitance Touch Sensors PESCE DFN
• Manufacturer: Freescale Semiconductor

Specifications of MPR031EP

• Package / Case: UDFN-8
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

MPR03X
8
3
3.1
The MPR03X has an analog front, a digital filter, and a touch recognition system. This data interpretation can be done many
different ways but the method used in the MPR03X is explained in this chapter.
3.2
MPR03X is a touch pad controller which manages two or three touch pad electrodes. An I²C interface communicates with the
host, and an optional interrupt output advises the host of electrode status changes. The interrupt output is a multiplexed function
with the third electrode input, so using the interrupt output reduces the number of electrode inputs to two.
The primary application for MPR03X is the management of user interface touch pads. Monitoring touch pads involves detecting
small changes of pad capacitance. MPR03X incorporates a self calibration function which continually adjusts the baseline
capacitance for each individual electrode. Therefore, the host only has to configure the delta thresholds to interpret a touch or
release.
MPR03X uses a state machine to operate a capacitive measurement engine to analyze the electrodes and determine whether a
pad has been touched or released. Between measurements the MPR03X draws negligible current. The application controls
MPR03X's configuration, making trade-offs between noise rejection, touch response time, and power consumption.
3.3
The touch sensor system can be tailored to specific applications by varying the following: a capacitance detector, a raw data low
pass filter, a baseline management system, and a touch detection system. In the following sections, the functionality and
configuration of each block will be described.
Electrodes can be connected to the MPR03X in two different configurations, one with an IRQ and one without
I ² C Serial
Interface
INT
Functional Overview
Introduction
Understanding the Basics
Implementation
V SS
MPR03X with 2 Electrodes and 2 Pads
75k
REXT
SCL
SDA
MPR03X
Figure 13. MPR03X Pad and Interrupt Connection Options
V DD
V SS
ELE0
ELE1
1
2
I ² C Serial
Interface
V SS
75k
MPR03X with 3 Electrodes and 3 Pads
SCL
SDA
REXT
MPR03X
V DD
V SS
Freescale Semiconductor
ELE0
ELE1
ELE2
(Figure
1
2
13).
Sensors
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