Primary current controlled low-voltage LED driver
Publication Date: 2002-Nov-05
The IP.com Prior Art Database
Primary current controlled low-voltage LED driver.
Controlling the current through an LED implies in most cases using a sensing resistor. Especially for applications where a single LED is to be controlled, this sensing resistor contributes for a large part to the conversion losses.
A more cost effective and less PCB space demanding solution can be achieved by sensing the average current from the power supply (e.g. 24V). It is possible to achieve a sufficient degree of load current regulation with a fairly accurate power supply.
A further advantage of the described method is that the power supply will not exhibit a negative impedance. So there is no need for incorporation of an extensive under-voltage lock out circuit.
Modules of DC/DC converter as power supply and LED modules can easily be placed in parallel when using this approach.
An example of the described solution is shown in the figure below.