34844 datasheet(19/37 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

34844

FUNCTIONAL DEVICE OPERATION

OPERATIONAL MODES

the PIN and NIN pins are enabled to scale the current

capability per string and may be disable by setting 2.2V in the

corresponding terminal.

Also in this mode, the device can be enabled as follows:

+ EN pin + PWM signal (Two Signals): In this configuration

the PWM signal applied to PWM pin will be in charge of

controlling the LED dimming and a second signal will enable

or disable the chip through the EN pin. Figure 17

+ PWM Signal tied to SDA pin (Just ONE signal): In this

configuration the PWM pin should be tied to SDA pin. The

PWM signal applied to PWM pin will be in charge of

controlling LED dimming and enable the device every time

the PWM is active. For this configuration EN pin should be

LOW.

POWER DOWN MODE

If the input voltage falls below the UVLO threshold, the

device enters automatically into power down mode. The

device operates only when the EN pin is high, or the EN bit in

current is reduced below 2

μA when there is no I2C activity,

and it rises up when I2C interface is enabled.

34844 Datasheet(PDF) 19 Page - Freescale Semiconductor, Inc