Ocean Optics LLS Series LED - Manual (Page 6)

LLS Series Installation and Operation Instructions
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Internal/External Control (J5)
When in the EXT position, as shown above, modulation will follow the external TTL input control
directly. When in the INT position it will switch to a 500
μs pulse which triggers on a rising edge. This
feature is extremely important when modulating deep UV LEDs (250nm-355nm). These LEDs should
not be modulated faster than 150Hz. All other LEDs can be modulated up to 1 kHz. The circuit for
these UV LEDs is pre-configured to deliver a 200mA maximum pulse current. The LLS comes pre-
configured to work in this internal pulse width mode.
Intensity Control Jumper (J6)
When externally controlling the intensity, the control input channel must be set via the external control
jumper to coordinate with the desired input channel. The control input voltage is from 0 to 2.5 Volts.
The drive current will proportionally follow this voltage. For example, if the control voltage is 1.25
Volts, the LED will be driven 1.25⁄ 2.5 Volts or 50% of the maximum current. Therefore if the LED
circuit is configured for 1500mA maximum, the drive current will be 750mA. (See the table in
LLS
Models for current drive specifications.) Do not drive this voltage with more than 2.5 Volts as damage
to LEDs may occur. This control will work for both Pulse and CW modes.
Exchanging LED Modules
LED modules can be easily exchanged in the LLS. Each LED module has a small printed circuit
board that programs the drive current for the device attached to it. Therefore there is no need to
worry about driving too much current into the new LED module. Just plug it in and go.
It is not recommended to replace LEDs without exchanging the included module. These modules
also have EEPROM memory that store critical information about the devices. The EEPROM
memory is read by the external USB controller and can identify which LEDs are in which
locations.
LED Module Types
There are two types of modules, high power and fiber-coupled. The high power modules have an
attached heatsink. To replace these, it is necessary to have a 5/16” nut driver and Phillips head
screwdriver.
High Power LED Module Installed High Power LED Module