EVL6563S-250W STMicroelectronics, EVL6563S-250W Datasheet - Page 23

• Manufacturer Part Number: EVL6563S-250W
• Description: EVAL BOARD FOR L6563(250W)
• Manufacturer: STMicroelectronics
• Type: Power Factor Correctionr

Specifications of EVL6563S-250W

• Main Purpose: Power Management, Power Factor Correction
• Embedded: No
• Utilized Ic / Part: L6563
• Primary Attributes: 250W Power Factor Correction and Preregulator Combination
• Secondary Attributes: Transition Mode & Active Tracking Boost Function.
• Board Size: 88 mm x 116 mm
• Maximum Operating Temperature: + 50 C
• Operating Supply Voltage: 90 V to 265 V
• Product: Power Management Modules
• Dimensions: 88 mm x 116 mm
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: L6563S
• Other names: 497-10489

AN3119
4.7
Power management and housekeeping functions
A special feature of the L6563S is that it facilitates the implementation of the “housekeeping”
circuitry needed to coordinate the operation of the PFC stage to that of the cascaded DC-
DC converter. The functions realized by the housekeeping circuitry ensure that transient
conditions like power-up or power-down sequencing or failures of either power stage be
properly handled. The L6563S provides some pins to do that.
As already mentioned, one communication line between the L6563S and the PWM
controller of the cascaded DC-DC converter is the PWM_LATCH (pin #8), which is normally
open when the PFC works properly. It goes high if the L6563S loses control of the output
voltage (because of a failure of the control loop) or if the boost inductor saturates, with the
aim of also latching off the PWM controller of the cascaded DC-DC converter.
A second communication line can be established via the disable function included in the
RUN pin. Typically, this line is used to allow the PWM controller of the cascaded DC-DC
converter to shut down the L6563S in the case of light load, to minimize the no-load input
consumption of the power supply.
Examples of intefacing some ST half-bridges controllers are shown in
Figure 34. L6563S on/off control by a cascaded converter controller via the PFC_OK
The third communication line is the PWM_STOP pin (# 9), which works in conjunction with
the RUN pin (#10). The purpose of the PWM_STOP pin is to inhibit the PWM activity of both
the PFC stage and the cascaded DC-DC converter. The pin is an open collector, normally
open, that goes low if the device is disabled by a voltage lower than 0.8 V on the RUN pin
(#10). It is important to point out that this function works correctly in systems where the PFC
stage is the master and the cascaded DC-DC converter is the slave or, in other words,
where the PFC stage starts first, powers both controllers and enables/disables the operation
of the DC-DC stage. This function is quite flexible and can be used in different ways. In
systems comprising an auxiliary converter and a main converter (e.g. desktop PC's, silver
box or high end flat-TVs, and monitors), where the auxiliary converter also powers the
controllers of the main converter, the RUN pin (#10) can be used to start and stop the main
converter. In the simplest case, to enable/disable the PWM controller the PWM_STOP pin
(#9) can be connected to either the output of the error amplifier or, if provided the chip, to the
soft-start pin.
The EVL6563S-250W offers the possibility to test these function by connecting it to the
cascaded converter via the R30, R31, R32 series resistors. Regarding the PWM_STOP pin
or RUN pin
Doc ID 16849 Rev 2
Test results and significant waveforms
Figure
34.
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