| 摘要 |
<p>PURPOSE: A constant current supply device and an LED driving unit including the same are provided to supply an effective constant current to a load without the smoothing condenser with large capacity by adaptively determining a block section of a switch according to the conduction period of the switch. CONSTITUTION: A constant current supply device includes a block circuit, a conduction period measuring unit(95), a timer unit(97), and a memory(96). If an instantaneous current flowing in a switch(Q1) exceeds a limit current, a block circuit blocks the switch. A conduction section measuring unit measures the conduction period of the switch. The conduction period measuring unit is a digital counter. The timer unit blocks the switch for the block period determined according to the measured conduction period. The timer unit is a digital timer. The memory stores the block period determined by the measured conduction period.</p> |
