Pulse width modulation signal generation circuit and lamp control system including the same

A lamp control system comprising:

• a lamp;
• a lamp driving circuit configured to generate a pulse width modulation signal and operate the lamp using the pulse width modulation signal;
• and
• an adjustment circuit connected to the lamp driving circuit to allow a pulse width and a cycle of the pulse width modulation signal to be adjusted,
• wherein the adjustment circuit includes a capacitor configured to adjust a voltage of a first node via a charging or discharging operation,
• wherein the lamp driving circuit includes:
• a switch circuit configured to supply a driving signal for operating the lamp to the lamp in response to a control signal;
• a pulse width modulation signal generation circuit connected to the capacitor, wherein the pulse width modulation signal generation circuit is configured to control the charging and the discharging of the capacitor to generate the pulse width modulation signal;
• and
• a current control circuit configured to generate the control signal in response to the pulse width modulation signal, and
• wherein the pulse width modulation signal generation circuit includes:
• the first node connected to the capacitor;
• a charging control circuit connected to and located between a voltage line configured to supply an operating voltage and the first node, and wherein the charging control circuit is configured to control the charging operation for the capacitor in response to an activated charging control signal;
• a discharging control circuit connected to and located between the first node and ground, wherein the discharging control circuit is configured to control the discharging operation for the capacitor in response to an activated discharging control signal;
• a comparison circuit configured to generate a comparison signal by comparing a first reference voltage and a second reference voltage with the voltage of the first node;
• and
• a control logic circuit configured to generate the pulse width modulation signal whose level changes based on a level change of the comparison signal and determine a level change timing of the charging control signal and the discharging control signal using the level change of the comparison signal.

A pulse width modulation signal generation circuit comprising:

• a voltage to current converter configured to convert a predetermined voltage into a second current;
• a charging/discharging control circuit configured to generate a first current in response to a bias voltage, control a charging operation for a capacitor connected via a first node in response to the first current and a charging control signal, and control a discharging operation for the capacitor in response to the second current and a discharging control signal;
• a comparison circuit configured to generate a first comparison signal by comparing a first reference voltage with a voltage of the first node, and generate a second comparison signal by comparing a second reference voltage with the voltage of the first node;
• and
• a control logic circuit configured to generate the charging control signal and the discharging control signal using a level change of the first comparison signal and a level change of the second comparison signal, and generate a pulse width modulation signal using a level change timing of the charging control signal and a level change timing of the discharging control signal.