8 Channel Capacitive Touch Sensor with 2 LED Drivers
Datasheet
‘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.
Table 5.48 LED Polarity Behavior
LED
OUTPUT
CONTROL
REGISTER
OR TOUCH
LED
APPEARANCE
POLARITY
MAX DUTY
MIN DUTY
BRIGHTNESS
minimum % of
time that the LED
is on (logic 0)
inverted
(‘0’)
maximum brightness
at min duty cycle
on at min duty
cycle
0
1
0
not used
maximum brightness
at max duty cycle.
Brightness ramps
from min duty cycle
to max duty cycle
maximum % of
time that the LED
is on (logic 0)
minimum % of
time that the LED
is on (logic 0)
inverted
(‘0’)
according to
LED behavior
non-
inverted
(‘1’)
minimum % of
time that the LED
is off (logic 1)
maximum brightness
at 100 minus min
duty cycle.
on at 100 - min
duty cycle
not used
For Direct behavior,
maximum brightness
is 100 minus max
duty cycle. When
breathing, max
brightness is 100
minus min duty cycle.
Brightness ramps
from 100 - min duty
cycle to 100 - max
duty cycle.
non-
inverted
(‘1’)
maximum % of
time that the LED
is off (logic 1)
minimum % of
time that the LED
is off (logic 1)
according to
LED behavior
1
5.29
Linked LED Transition Control Register
Table 5.49 Linked LED Transition Control Register
ADDR
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
Linked LED
Transition
Control
LED2_
LTRAN
LED1_
LTRAN
77h
R/W
-
-
-
-
-
-
00h
The Linked LED Transition Control register controls the LED drive when the LED is linked to a
capacitive touch sensor input. These controls work in conjunction with the INV_LINK_TRAN bit (see
Section 5.6.2, "Configuration 2 - 44h") to create smooth transitions from host control to linked LEDs.
Bit 1 - LED2_LTRAN - Determines the transition effect when LED2 is linked to CS2.
‘0’ (default) - When the LED output control bit for CS2 is ‘1’, and then CS2 is linked to LED2 and
no touch is detected, the LED will change states.
‘1’ - If the INV_LINK_TRAN bit is ‘1’, when the LED output control bit for CS2 is ‘1’, and then CS2
is linked to LED2 and no touch is detected, the LED will not change states. In addition, the LED
state will change when the sensor pad is touched. If the INV_LINK_TRAN bit is ‘0’, when the LED
SMSC CAP1128
Revision 1.32 (01-05-12)
DATA6S7HEET
SMSC [ SMSC CORPORATION ]
