Barco SLM R12 Plus, Service Manual, Page: 118 / 281

15. Lamp Power Supply R7633705
3 PWM (pulse width modulated) outputs
VL_MIN
The PWM signal is integrated with R253 and C251 to an analog signal (1 to 5V).
This voltage controls the maximum output current of the LPS.
With VL_MIN = at low values (depending on the adjusted power) the maximum output current is kept
below 110A (hardware current limit in the LPS).
With VL_MIN = 2V the maximum output current is kept below the value <adjusted power level in Watts>
divided by 20V.
With VL_MIN = 5V the maximum output current is kept below the value <adjusted power level in Watts>
divided by 50V.
FAN_SPD This PWM signal drives the fans via a PWM converter on the R7632113 module.
EEPROM I210
This EEPROM contains values that control protection levels (temperature and voltage levels), lamp voltage ranges, look up tables
for temperature measurements conversion, and module serial number).
AMBIENT TEMP SENSOR I215
This I2C controlled circuit measures the module internal ambient temperature.
FEEDBACK CIRCUITS ON SHEET 2/5
The signals VS and IS coming from module R7632113 via connector J603 are representative of the module output levels:
• VS is a measure of the module output voltage, sensitivity: 0.1V for 1V at the output.
• IS is a measure of the module output current, sensitivity: 0.04V for 1A at the output.
Both are multiplied in the analog multiplier I251, where also an offset voltage equal to the signal DIM is added.
The resultant output voltage POUT_S is via an analog optocoupler I270 coupled to the primary LPS controller (on sheet 5/5).
The LPS controller regulates the LPS output such that POUT_S is kep constant.
As a result the product VS x IS is also constant, so the module is keeping its output power level at a constant level, depending on
the value of the signal DIM.
(The clamp circuit in I250, output pin 8 is not used, as diode D251 is not mounted).
SIGNAL VIN_RMS on sheet 3/5
This analog voltage is a measure of the ac input mains voltage, sensitivity 0.02Vdc for 1Vrms at the input. Its level controls:
• the output voltage of the PFC: 380Vdc for mains voltages above 180Vrms, 280Vdc for mains voltages below 175Vrms (circuit
around I370 and Q370, and signal PFC_OUT_LEVEL that modifies the feedback in the PFC controller on sheet 4/5).
• the undervoltage protection that prevents the PFC startup for too low mains voltages. See next paragraph.
MAINS_RANGE SELECT on sheet 3/5
With the signal MAINS_RANGE SELECT, several circuits are adjusted to different values depending on the input mains range. The
module has two ranges, depending on the level of MAINS_RANGE SELECT.
230Vac only range
Signal MAINS_RANGE SELECT is low, and Q360/361 are conducting:
• The level at pin 7 of I370 is increased and prevents startup of the PFC for input voltages below 190Vac.
• The 5V level on POWER_LIMIT_RANGE programs the PFC controller I420 on sheet 4/5 for 3kW max.
120/230Vac universal range
Signal MAINS_RANGE SELECT is high, and Q360/361 are blocked
• The lower level at pin 7 of I370 prevents startup of the PFC for input voltages below 85Vac.
• The low level on POWER_LIMIT_RANGE programs the PFC controller I420 on sheet 4/5 for 1.5kW max.
15.6.3 Power Factor Corrector (sheet 4/5)
Introduction
The PFC must take current from the mains line in phase with the voltage which is understood to have a sinus shape. This function
can be combined with a stabilization of the output by adjusting the amplitude of the current using a boost converter circuit. All this
is controlled by the L4981A (I420).
116 R5976820 SLM R12+ PERFORMER 08/03/2005