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LED Driver ICs Forum Discussions

j_oehmen
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Moderator 10 replies posted 5 replies posted 10 questions asked
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e.g. when connecting 50 Ohm to the output instead of LEDs
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j_oehmen
Moderator
Moderator 10 replies posted 5 replies posted 10 questions asked
Moderator
In case of a resistive load (e.g. 50 Ohm) is connected to the output of an linear current source instead of real LEDs and the supply voltages increases slowly the output channel may not turn on.

Basic and Basic+ LED drivers are not designed for driving pure resistive loads. In case the output voltage VOUT is below the required output voltage for current control VOUT(CC) (see parameter 7.2.7 in the datasheet) the main power stage is operating with the short circuit protection mechanism integrated in our LED drivers. At start-up when VOUT < VOUT(CC) the device uses a startup current of a few 100 µA to rise the output voltage. Once the output voltage is above VOUT(CC) the main current control loop is starting to work and the target current is flowing.

Recommendation would be change the load to add diodes in series to the resistor to achieve a forward voltage threshold greater than VOUT(CC) at the start-up current. Further details on the diagnostic features in LITIX Basic+ can be found in LITIX Basic+ Diagnostic features

See also the LITIX Basic+ page for more information.

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j_oehmen
Moderator
Moderator 10 replies posted 5 replies posted 10 questions asked
Moderator
In case of a resistive load (e.g. 50 Ohm) is connected to the output of an linear current source instead of real LEDs and the supply voltages increases slowly the output channel may not turn on.

Basic and Basic+ LED drivers are not designed for driving pure resistive loads. In case the output voltage VOUT is below the required output voltage for current control VOUT(CC) (see parameter 7.2.7 in the datasheet) the main power stage is operating with the short circuit protection mechanism integrated in our LED drivers. At start-up when VOUT < VOUT(CC) the device uses a startup current of a few 100 µA to rise the output voltage. Once the output voltage is above VOUT(CC) the main current control loop is starting to work and the target current is flowing.

Recommendation would be change the load to add diodes in series to the resistor to achieve a forward voltage threshold greater than VOUT(CC) at the start-up current. Further details on the diagnostic features in LITIX Basic+ can be found in LITIX Basic+ Diagnostic features

See also the LITIX Basic+ page for more information.
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