PWM controlling circuit and LED driver circuit having the same

A Light Emitting Diode (LED) driver circuit, comprising:

• a voltage detector comprising:
• comparators respectively corresponding to LED arrays, the comparators being configured to:
• compare a feedback voltage signal corresponding to each of the LED arrays with a preset voltage;
• and
• indicate whether each LED array is connected to a voltage detector based upon the comparison;
• and
• a minimum feedback voltage selector configured to:
• receive the indications of whether each of the LED arrays is connected to the voltage detector;
• receive the feedback voltage signals corresponding to the LED arrays;
• detect a minimum voltage signal among the received feedback voltage signals corresponding to LED arrays that are determined to be connected;
• and
• output the minimum voltage signal as the minimum feedback voltage;
• a controller configured to output a control signal to control boosting of the LED arrays based on the detected minimum feedback voltage;
• a Pulse Width Modulation (PWM) signal generator configured to output a PWM signal based on the outputted control signal;
• and
• a driving voltage generator configured to supply a driving voltage commonly to the LED arrays based on the PWM signal.

A Pulse Width Modulation (PWM) controlling circuit comprising:

• a voltage detector configured to:
• determine, for a plurality of light emitting diode (LED) arrays, whether each of the LED arrays is connected to the voltage detector based upon a corresponding feedback voltage signal;
• output a selection signal indicating whether all of the LED arrays are connected to the voltage detector;
• and
• output a control voltage to control boosting of the LED arrays based on the determined connection status;
• and
• a controller configured to select from a first control signal to abort boosting of the LED arrays and a second control signal to control boosting of the LED arrays, based on the selection signal, the second control signal being based on the control voltage;
• a PWM signal generator configured to output a PWM signal based on the selected control signal.