FAQ's - LED Sources and Controllers

IMPORTANT : LED's can ONLY be driven by a constant-current source, and not a voltage source.

B-001: Why is a constant current source and NOT a voltage source required for operating an LED?

[A] A voltage source should NEVER be used, in order to avoid permanent damage to the LED. Below is a typical "v-i" curve of an LED, which llustrates that a tiny change in voltage past a threshold voltage (Vd) could lead to a huge surge of driving current, leading to the LED being over driven and burned. There is usually no way to control the supply voltage to precisely match Vd of the, as Vd is not just dependent on the LED's material/design but also on environmental conditions the LED is operated within such as the ambient temperature. Additionally, driving the LED below supply voltage lower than Vd is not an option either. The following will occur: (1)The LED will not emit light below threshold; and (2) if one attempts to increase the voltage, as soon as one sees the light (i.e. supplied voltage surpasses Vd) the LED may have already been subjected to excessive current and become damaged. The proper solution is to use a current source which controls and limits the driving current directly.

B-002: Do Mightex's LED controllers only work for Mightex's LED light sources?

[A] No. Mightex's LED controllers are UNIVERSAL, and they are capable of driving LEDs of any made, with any wavelength/color, and of a wide range of output powers.

 

B-003: Do I have to connect a PC to Mightex's LED controllers all the time?

[A] No. Mightex's LED controllers have built-in non-volatile memory, which can be used to store the control information including control mode setting and waveform data. In other words, you may (use a PC to) program the LED controller, disconnect it from the PC, and then use it as a standalone device. Therefore, Mightex's LED controllers can be pre-programmed to carry out a wide range of tasks, without having to be connected to a PC all the time.

 

B-004: If I need more channels than your LED controllers have, what should I do?

[A] Mightex's LED driver software is capable of simultaneously driving multiple LED controllers, viz. the LED controllers are 'stackable' to up to 16 units and all of them can still be controlled by the same driver software via the same GUI. For example, by connecting 2x (or 3x) SLC-AA04-x 4-Channel LED Drivers to a PC through either RS232 or USB, one could easily construct an 8x (or a 12x) channel LED driver. The following is a schematic diagram showing how this can be done.

 

 

B-005: Can I write my own application software to control Mightex's LED drivers?

[A] Yes, Mightex's LED controllers come with a RS232 command set and a powerful SDK. You could write your own application software based on the command set or the SDK, or you could utilize our OEM services to develop a custom application software for you. For custom OEM services, please call 1-416-840-4991 or 1-925-218-1885, or email sales@mightex.com.

 

B-006: Do the SLC-series LED drivers provide IAP ( In Application Programming ) capability?

[A] Yes, SLC-series LED controllers all have in-field firmware upgradability, which can be done via Mightex's standard LED driver software. With this capability, customers can upgrade the firmware with ease.

 

B-007: How do I select the best LED driver for my application? Do you have an LED controller/driver selection guide?

[A] Below is a LED driver/controller selection guide:

 

B-007: What is the life time of LEDs?

[A] If operated within the LED's current specification and with good heat dissipation, an LED should last at least several 10,000 hours. LED's primary failure mode is over-heating, usually due to improper driving conditions such as over-current. LED failure due to over-heating is considered 'mis-handling', and it is not covered by product warranty.

 

B-008: What is the bandwidth and accuracy of LED wavelength?

[A] Bandwidth and wavelength accuracy depend on the center wavelength of the LED.  Usually the bandwidth is 20-50nm and wavelength accuracy is between +/-3nm to +/-7nm.

 

B-009: For a Mightex LED with "open-wire" type cabling, how should I connect it to my Mightex LED controller?

[A] Please see below images. The RED wire of the LED's power cable should be connected to the connector terminal labeled "LED+", and the Black wire should be connected to the connector terminal labeled "LED-". Connecting the LED in reversed polarity may cause permanent damage and should be avoided.