CAP1214 datasheet(94/107 Pages) MICROCHIP

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Multiple Channel Capacitive Touch Sensor and LED Driver

Datasheet

Revision 1.0 (08-30-10)

SMSC CAP1214

DATASHEET

Bit 3 - VAR_PWM - Determines whether fixed or variable PWM frequency will be used for LED11.

‘0’ (default) - LED11 PWM frequency is fixed, regardless of pulse/breathe period and/or minimum

and maximum duty cycle settings.

‘1’ - LED11 PWM frequency is variable, based on pulse/breathe period (if behavior is not Direct)

and minimum and maximum duty cycle settings.

Bits 2 - 0 - LED11_CLK[2:0] - Determines the base clock frequency used for LED11, as shown in

Table 6.82.

APPLICATION NOTE:

If the base frequency is reduced, but the number of steps is not reduced, resolution may be

lost and period lengths may be different than calculated.

6.57

LED Pulse and Breathe Duty Cycle Registers

The LED Pulse 1, Pulse 2, Breathe, and Direct Duty Cycle Registers determine the minimum and

maximum duty cycle settings used for the LEDs for each LED behavior. These settings affect the

brightness of the LED when it is fully off and fully on.

The LED driver duty cycle will ramp up from the minimum duty cycle to the maximum duty cycle and

back down again.

Table 6.82 LED11_CLK Decode

LED11_CLK[2:0]

CLOCK RUNNING LED11

500kHz (default)

125kHz

62.5kHz

31.25kHz

15.625kHz

7.8125kHz

500kHz

Table 6.83 LED Period and Breathe Duty Cycle Registers

ADDR

R/W

DEFAULT

90h

R/W

LED Pulse 1

Duty Cycle

LED_P1_MAX_DUTY[3:0]

LED_P1_MIN_DUTY[3:0]

F0h

91h

R/W

LED Pulse 2

Duty cycle

LED_P2_MAX_DUTY[3:0]

LED_P2_MIN_DUTY[3:0]

F0h

92h

R/W

LED Breathe

Duty Cycle

LED_BR_MAX_DUTY[3:0]

LED_BR_MIN_DUTY[3:0]

F0h

93h

R/W

Direct Duty

Cycle

LED_DR_MAX_DUTY[3:0]

LED_DR_MIN_DUTY[3:0]

F0h

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