CAP1208 datasheet(20/67 Pages) MICROCHIP

20 / 67 page

8-Channel Capacitive Touch Sensor

Datasheet

DS00001570B-page 20

 2014 Microchip Technology Inc.

4.1

Power States

The CAP1208 has 3 power states depending on the status of the STBY and DSLEEP bits (see Section

5.1, "Main Control Register"). When the device transitions between power states, previously detected

touches (for channels that are being de-activated) are cleared and the sensor input status bits are

reset.

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

in the Active state (see Section 5.7, "Sensor Input Enable Register").

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

in the Standby state (see Section 5.21, "Standby Channel Register"). Interrupts can still be

generated based on the enabled channels. The device will still respond to communications

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

consumption in this state is dependent on the number of sensor inputs enabled as well as

averaging, sampling time, and cycle time.

3. Deep Sleep - When the DSLEEP bit is set, the device is in its lowest power state. It is not

monitoring any capacitive sensor inputs. While in Deep Sleep, the CAP1208 can be awakened by

SMBus communications targeting the device. This will not cause the DSLEEP to be cleared so the

device will return to Deep Sleep once all communications have stopped. The device can be

returned to the Active state of operation by clearing the DSLEEP bit.

4.2

Reset

The Power-On Reset (POR) circuit holds the device in reset until VDD has reached an acceptable level,

Power-on Reset Release Voltage (VPORR), for minimum operation. The power-up timer (PWRT) is

used to extend the start-up period until all device operation conditions have been met. The power-up

timer starts after VDD reaches VPORR. POR and PORR with slow rising VDD is shown in Figure 4.2.

The Brown-Out Reset (BOR) circuit holds the device in reset when VDD falls to a minimum level, VBOR

for longer than the BOR reset delay (tBORDC). After a BOR, when VDD rises above VPORR, the power-

up timer is started again and must finish before reset is released, as shown in Figure 4.2.

4.3

Capacitive Touch Sensing

The CAP1208 contains eight (8) independent capacitive touch sensor inputs. Each sensor input has

dynamic range to detect a change of capacitance due to a touch. Additionally, each sensor input can

be configured to be automatically and routinely recalibrated.

Figure 4.2 POR and PORR With Slow Rising VDD and BOR with Falling VDD

VDD

VBOR

TPWRT

GND

Undefined

SYSRST

VPOR

VPORR

TBORDC TPWRT

CAP1208 Folha de dados(PDF) 20 Page - Microchip Technology

CAP1208 Folha de dados(HTML) 20 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67

Folha de dados Download

Ligação URL