CAP1026 datasheet(55/70 Pages) SMSC

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6 Channel Capacitive Touch Sensor with 2 LED Drivers

Datasheet

SMSC CAP1026

Revision 1.1 (08-05-09)

DATASHEET

Note 5.3

For example: when polarity is non-inverted, if min duty cycle is 0, then the LED would be

at logic 1 (off) 0% of the time. It will be at logic 0 (on), 100% of the time (100 - min duty

cycle).

Bit 1 - LED2_DR - Determines whether LED2 output is driven high or low.

‘0’ (default) - The LED2 output is driven at the minimum duty cycle or not actuated.

‘1’ - The LED2 output is High Z or driven at the maximum duty cycle or actuated.

Bit 0 - LED1_DR - Determines whether LED1 output is driven high or low.

5.27

LED Behavior Register

The LED Behavior registers control the operation of LEDs. Each LED pin is controlled by a 2-bit field

and the behavior is determined by whether the LED is linked to a Capacitive Touch Sensor or not.

If the corresponding LED output is linked to a Capacitive Touch Sensor than the Start and Stop triggers

are used. The defined behavior will activate when the Start Trigger is met and will stop when the Stop

Trigger is met.

If the LED output is not associated with a a Capacitive Touch Sensor, then the appropriate behavior

will be enabled / disabled by the LED Output Control register. If the respective LEDx_DR bit is set to

a logic ‘1’ then this will be associated as a “touch” and if the LEDx_DR bit is set to a logic ‘0’ then this

will be associated as a “release”.

The LED Polarity Control register will determine the non actuated state of the LED outputs. If the LED

Polarity Control register is set to be inverted (default), then an non actuated LED pin will be driven to

a logic ‘1’ state and the LED will be off. If the LED Polarity Control register is set to be non-inverted,

then the non actuated LED pin will be driven to the logic ’0’ state and the LED will be on.

Table 5.41 LED Polarity Behavior

LED

OUTPUT

CONTROL

POLARITY

MAX DUTY

MIN DUTY

LED

BEHAVIORS

BRIGHTNESS

LED

APPEARANCE

inverted

maximum % of

time that the LED

is on (logic 0)

minimum % of

time that the LED

is on (logic 0)

off

maximum brightness at

minimum duty cycle

on at minimum

duty cycle

inverted

maximum % of

time that the LED

is on (logic 0)

minimum % of

time that the LED

is on (logic 0)

maximum brightness at

max duty cycle. Brightness

ramps from min to max

according to

LED behavior

non-

inverted

maximum % of

time that the LED

is off (logic 1)

minimum % of

time that the LED

is off (logic 1)

off

maximum brightness at 100

- min duty cycle

on at 100 - min

duty cycle

(Note 5.3)

non-

inverted

maximum % of

time that the LED

is off (logic 1)

minimum % of

time that the LED

is off (logic 1)

maximum brightness at 100

- min duty cycle. Brightness

ramps from max to min

according to

LED behavior

Table 5.42 LED Behavior Register

ADDR

R/W

DEFAULT

81h

R/W

LED Behavior

LED2_CTL[1:0]

LED1_CTL[1:0]

00h

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