TLD5095EL Datasheet, PDF (14/31 Pages) Infineon Technologies AG – DC/DC Boost, Buck-Boost, SEPIC controller

TLD5095EL
Enable and Dimming Function
7
Enable and Dimming Function
7.1
Description
The enable function powers on or off the device. A valid logic low signal on enable pin EN/PWMI powers off the
device and current consumption is less than 10 µA. A valid logic high enable signal on enable pin EN/PWMI
powers on the device. The enable function features an integrated pull down resistor which ensures that the IC is
shut down and the power switch is off in case the enable pin EN is left open.
In addition to the enable function described above, the EN/PWMI pin detects a pulse width modulated (PWM) input
signal that is fed through to an internal gate driver. The internal gate driver outputs the same PWM signal on the
PWMO pin to an external n-channel enhancement mode MOSFET for PWM dimming an LED load. PWM dimming
an LED is a commonly practiced dimming method to prevent color shift in an LED light source. Moreover the PWM
output function may also be used for to drive other types of loads besides LED.
The enable and PWM input function share the same pin. Therefore a valid logic low signal at the EN/PWMI pin
needs to differentiate between an enable power off signal or an PWM low signal. The device differentiates between
an enable off command and PWM dimming signal by requiring the signal at the EN/PWMI pin to stay low for a
minimum of 8 ms.
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Block Diagram and Simplified Application Circuit Enable and LED Dimming
Datasheet
14
Rev. 1.1, 2009-12-16