8 Channel Capacitive Touch Sensor with 8 LED Drivers
Datasheet
The LED Pulse 2 Period register determines the overall period of a pulse operation as determined by
the LED_CTL registers (see Table 5.43 - setting 10b). Each LSB represents 32ms so that a setting of
14h (20d) would represent a period of 640ms. The total range is from 32ms to 4.06 seconds (see
Table 5.45).
APPLICATION NOTE: Due to constraints on the LED Drive PWM operation, any Breathe Period less than 160ms
(05h) may not be achievable. The device will breathe at the minimum period possible as
determined by the period and min / max duty cycle settings.
The Pulse 2 Behavior is shown in Figure 5.3 for non-inverted polarity and in Figure 5.4 for inverted
polarity.
Release Detected
Touch Detected
Normal – untouched
operation
Normal – untouched
operation
X additional pulses after release
(100% - Pulse 2 Min Duty Cycle) *
Brightness
LED
Brightness
. . .
Breathe
and Pulse
Period
(100% - Pulse 2 Max Duty Cycle) * Brightness
(P2_PER)
Figure 5.3 Pulse 2 Behavior with Non-Inverted Polarity
Release Detected
Touch Detected
Normal – untouched
operation
Normal – untouched
operation
X additional pulses after release
Pulse 2 Max Duty Cycle * Brightness
LED
Brightness
. . .
Breathe
and Pulse
Period
Pulse 2 Min Duty Cycle * Brightness
Figure 5.4 Pulse 2 Behavior with Inverted Polarity
5.30 LED Breathe Period Register
Table 5.47 LED Breathe Period Register
ADDR
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
5Dh
LED Breathe
Period
BR_
PER6
BR_
PER5
BR_
PER4
BR_
PER3
BR_
PER2
BR_
PER1
BR_
PER0
86h
R/W
-
SMSC CAP1088
Revision 1.1 (08-05-09)
DATA6S1HEET
SMSC [ SMSC CORPORATION ]
