Datasheet

8 Channel Capacitive Touch Sensor with 8 LED Drivers
Datasheet
Revision 1.32 (01-05-12) 78 SMSC CAP1188
DATASHEET
5.37 LED Direct Ramp Rates Register
The LED Direct Ramp Rates register control the rising and falling edge time of an LED that is
configured to operate in Direct behavior mode. The rising edge time corresponds to the amount of time
the LED takes to transition from its minimum duty cycle to its maximum duty cycle. Conversely, the
falling edge time corresponds to the amount of time that the LED takes to transition from its maximum
duty cycle to its minimum duty cycle.
Bits 5 - 3 - RISE_RATE[2:0] - Determines the rising edge time of an LED when it transitions from its
minimum drive state to its maximum drive state as shown in Table 5.62.
Bits 2 - 0 - FALL_RATE[2:0] - Determines the falling edge time of an LED when it transitions from its
maximum drive state to its minimum drive state as shown in Table 5.62.
0 1 0 1 20% 17%
0 1 1 0 23% 20%
0 1 1 1 26% 23%
1 0 0 0 30% 26%
1 0 0 1 35% 30%
1 0 1 0 40% 35%
1 0 1 1 46% 40%
1 1 0 0 53% 46%
1 1 0 1 63% 53%
1 1 1 0 77% 63%
1 1 1 1 100% 77%
Table 5.61 LED Direct Ramp Rates Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
94h R/W
LED Direct
Ramp Rates
- - RISE_RATE[2:0] FALL_RATE[2:0] 00h
Table 5.62 Rise / Fall Rate Decode
RISE_RATE/ FALL_RATE/ BIT DECODE
RISE / FALL TIME (T
RISE
/ T
FALL
))2 1 0
0 0 0 0
0 0 1 250ms
Table 5.60 LED Duty Cycle Decode (continued)
X_MAX/MIN_DUTY [3:0]
MAXIMUM DUTY
CYCLE
MINIMUM DUTY
CYCLE3 2 1 0