CAP1203 datasheet(13/59 Pages) MICROCHIP

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 2013-2015 Microchip Technology Inc.

DS00001572B-page 13

4.0

GENERAL DESCRIPTION

The CAP1203 is a multiple channel capacitive touch sensor. It contains three (3) individual capacitive touch sensor

inputs with programmable sensitivity for use in touch sensor applications. Each sensor input is calibrated to compensate

for system parasitic capacitance and automatically recalibrated to compensate for gradual environmental changes.

The CAP1203includes Multiple Pattern Touch recognition that allows the user to select a specific set of buttons to be

touched simultaneously. If this pattern is detected, a status bit is set and an interrupt is generated.

The CAP1203 has Active and Standby states, each with its own sensor input configuration controls. Power consumption

in the Standby state is dependent on the number of sensor inputs enabled as well as averaging, sampling time, and

cycle time. Deep Sleep is the lowest power state available, drawing 5µA (typical) of current. In this state, no sensor

inputs are active, and communications will wake the device.

The device communicates with a host controller using SMBus / I2C. The host controller may poll the device for updated

information at any time or it may configure the device to flag an interrupt whenever a touch is detected on any sensor

pad.

A typical system diagram is shown in FIGURE 4-1:.

4.1

Power States

The CAP1203 has 3 power states depending on the status of the STBY and DSLEEP bits. When the device transitions

between power states, previously detected touches (for channels that are being de-activated) are cleared and the sen-

sor input status bits are reset.

Active - The normal mode of operation. The device is monitoring capacitive sensor inputs enabled in the Active

state.

Standby - When the STBY bit is set, the device is monitoring the capacitive sensor inputs enabled in the Standby

state. Interrupts can still be generated based on the enabled channels. The device will still respond to communi-

cations normally and can be returned to the Active state of operation by clearing the STBY bit. Power consump-

tion in this state is dependent on the number of sensor inputs enabled as well as averaging, sampling time, and

cycle time.

FIGURE 4-1:

SYSTEM DIAGRAM FOR CAP1203

CAP1203

Embedded

Controller

CS3

CS2

CS1

Touch

Button

Touch

Button

Touch

Button

VDD

GND

3.0V to 5.5V

10kOhm

resistors

3.0V to 5.5V

1.0uF

0.1uF

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