Auxiliary DC Output from AC/DC LED Driver

Auxiliary DC Output from AC/DC LED Driver
Aimtec AC/DC series LED drivers support applications which require an auxiliary output to power cooling fans or other specific luminary devices. 
Below is a simple example showing an AC/DC LED driver with the additional DC/DC converter as a branch to the LED strings. The luminary designer implementing this type of configuration must take into account the power drop consumed by the DC/DC converter (DC-DC Pinmax), and select an LED driver according to the power required to power the LED’s and the DC/DC converter.
Example: Aimtec AMER90-36250CAZ produces output current of 2.5A, and the DC/DC converter selected consumes 0.8A. The current drop available to a single LED string would be seen as 2.5A – 0.8A = 1.7A. The LED driver selected must include consideration for the power used by the DC/DC converter selected, and then the amount of current required for the LED type.  
Calculating “DC-DC Pinmax” examples:
AMSR-7805Z, Poutmax = 5V x 0.5A = 2.5W with efficiency (min) 85%, the Pin=Pout/0.85=2.94W (max)
AMSR-7812SZ, Poutmax = 12V x 0.5A = 6W with efficiency (min) 94%, the Pin=Pout/0.94=6.4W (max)
The AC-DC LED driver loading from additional DC-DC power converter will be approximately 8-19% for lowest power LED driver (AMEPR30-AZ paired with AMSR-78xxZ), and with the higher power drivers the loading ratio will improve appropriately. For higher power LED drivers (60-150W) loading requirements from a cooling fan typically 0.5-1W) will be significantly reduced.
Other considerations:
Use LED drivers which have VDC outputs matching the DC/DC converter input range (AMSR-Z input voltage range is 6.5-34VDC, therefore LED driver selection will have to be 12V or 24V DC output).

Notes: Information furnished is believed to be accurate and reliable. However, Aimtec assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Aimtec. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. Aimtec Products are not authorized for use as critical components in life support devices or systems without express written approval of Aimtec.                                                     © 2012 Aimtec  – All Rights Reserved