Datasheet ILD8150, ILD8150E (Infineon) - 8

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ILD8150/ILD8150E LED driver IC for high power LEDs with hybrid dimming down to 0.5% Functional description
100 x Iout/Iref [%] 0.5 0 DPWM_IN,OFF 0.5 DPWM_IN [%] DPWM_IN,ON
Figure 8 Dimming curve dim-to-off detail
The ILD8150 evaluates the PWM dimming input signal duty cycle DPWM_IN at the DIM pin. In analog dimming the duty cycle maps to a proportional CS reference voltage. In hybrid dimming the duty cycle maps to a hybrid dimming duty cycle using the hybrid dimming curve. The hybrid dimming frequency is fixed and does not relate to the input PWM frequency.
Figure 9
shows the details of the input PWM signal where DPWM_IN = tPWM_IN,ON ∙ fINPUT . VPWM_IN [V] time [s] tPWM_IN,ON 1/fINPUT
Figure 9 Input PWM signal 3.1.3 Digital soft-start
Soft-start is a feature that smooths output current transients during start-up. Output current smoothing is digitally managed by the IC and applies in case of abrupt dimming changes. When the IC goes to dim-to-off the output current smoothing applies resulting in a soft-stop behavior. Benefits are the avoidance of under shoots or over shoots at primary side reflecting in a stable power regulation and reduction of components stress. Digital soft-start uses of the PWM dimming signal. The PWM duty cycle sets the target dimming level and the PWM frequency sets the speed to reach that level. To lower PWM frequencies correspond a slower soft-start, to higher PWM frequencies correspond a faster soft-start. The output current ramps up to the target value in a determined soft start time tSS. tSS is defined as the time to reach the desired dimming level from a change in the PWM dimming signal. The number of steps of the soft-start ramp may vary depending on the actual and the target dimming level. Datasheet 8 V1.0 2019-01-31 Document Outline Features Potential applications Description Table of contents 1 Functional block diagram 2 Pin configuration 3 Functional description 3.1 Buck controller features 3.1.1 Output current regulation 3.1.2 Dimming 3.1.3 Digital soft-start 3.1.4 Low power mode 3.2 Protection features 3.2.1 Over-temperature protection 3.2.2 Under-voltage protection 4 Thermal and electrical characteristics 4.1 Package characteristics 4.2 Absolute maximum ratings 4.3 Operating conditions 4.4 Electrical characteristics 5 Package dimensions Disclaimer