Controlling cooling device with XLC4 control unit

Connect a cooling device to the XLC4 control unit to provide a stable temperature for save an homogenous operation of the Corona II modules.

A Corona II module is equipped with a temperature sensor that monitors the current temperature of the module. The temperature values are permanently sent to the XLC4 control unit and are used as input data for the temperature control function.

Controlling the cooling device

If the temperature reaches a specific level the VOUT port is activated.

To enable the function, set bit 3 in the XLC4 control register FA. For further information refer to command FA.

Example

Enable the function:

1. Do a logical disjunction of the output value and 0x0008.

2. Write the result in the command FA.

Adjust the switching temperatures

By default the XLC4 control unit uses the initially stored value for the warning temperature.

If you want to adjust the temperature limits, refer to command FC.

Monitoring the fans

Refer to Chromasens support for further information about the supported Corona II modules.

Fan monitoring is available for XLC4 firmware release from 5.1 or higher.

Functionality

Fan monitoring is working with a voltage measurement at the input ACTRL at pin1 of X5.

The fans are equipped with an open-drain-switching-output. This output is switched to ON if the fan is working. In the modules the outputs are connected with a serial resistor of 1100Ω to a common signal. This signal is connected to ACTRL. In the XLC4 control unit (starting with hardware release ES2) there is a pull-up resistor of 820Ω between the input ACTRL and VOUT.

If the fans are switched with VOUT and all fans are working, all the switching signals are set to Low signal. Depending on the number of the connected fans and the level of VOUT there will be a specific voltage at ACTRL. This voltage is measured by the XLC4 control unit.

For correct interpretation of the signal, the XLC4 control unit needs knowledge about the connected number of fans. This value is stored in the I²C chip on the Corona II module and is read out during start-up of the XLC4 control unit. With these values the XLC4 control unit calculates a specific alarm level for the signal from the fans.

To start fan monitoring refer to command FA.

Conditions for constant temperature of the Corona II module

The temperature of the Corona II module always has to be within a specific temperature range.

During the off-phase of the fan the Corona II module heats up by the power dissipation of the LEDs. At low ambient temperature the operating current of the Corona II module must be high enough to heat up until the temperature range for operation is reached.

During the on-phase of the fan the Corona II module is cooled down and the module temperature is within the limits. The temperature gradient of module temperature to ambient temperature depends on the power dissipation of the LEDs.
If the temperature gradient is above the maximum temperature limit minus the ambient temperature, the module temperature is too high and the operating current or the ambient temperature must be reduced.