8 Channel Capacitive Touch Sensor with 2 LED Drivers
Datasheet
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.
Bit 7 - ST_TRIG - Determines the start trigger for the LED Pulse behavior.
‘0’ (default) - The LED will Pulse when a touch is detected or the drive bit is set.
‘1’ - The LED will Pulse when a release is detected or the drive bit is cleared.
The Pulse 1 operation is shown in Figure 5.1 when the LED output is configured for non-inverted
polarity (LEDx_POL = 1) and in Figure 5.2 for inverted polarity (LEDx_POL = 0).
.
Touch Detected or
Release Detected
X pulses after touch or after release
Normal – untouched
Normal – untouched
operation
operation
(100% - Pulse 1 Min Duty Cycle) * Brightness
LED
Brightness
(100% - Pulse 1 Max Duty Cycle) * Brightness
Pulse 1 Period
(P1_PER)
Figure 5.1 Pulse 1 Behavior with Non-Inverted Polarity
Touch Detected or
Release Detected
X pulses after touch or after release
Pulse 1 Max Duty Cycle * Brightness
LED
Brightness
Normal – untouched
operation
Normal – untouched
operation
Pulse 1 Min Duty Cycle * Brightness
Pulse Period
(P1_PER)
Figure 5.2 Pulse 1 Behavior with Inverted Polarity
SMSC CAP1128
Revision 1.32 (01-05-12)
DATA7S1HEET
SMSC [ SMSC CORPORATION ]
