STMicroelectronics EVAL BOARD FOR L6563 EVL6563H-250W EVL6563H-250W Data Sheet
Product codes
EVL6563H-250W
L6563H
Application information
Doc ID 16047 Rev 3
33/49
Figure 46.
Interface circuits that let dc-dc converter's controller IC drive L6563H in
burst mode
burst mode
The third communication line is the pin PWM_STOP (#11), which works in conjunction with
the pin RUN (#12). 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.
The pin goes again open if the voltage on pin RUN exceeds 0.88 V. 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. The pin RUN
can be used to start and stop the main converter. In the simplest case, to enable/disable the
PWM controller the pin PWM_STOP can be connected to the output of the error amplifier
(
the pin RUN (#12). 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.
The pin goes again open if the voltage on pin RUN exceeds 0.88 V. 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. The pin RUN
can be used to start and stop the main converter. In the simplest case, to enable/disable the
PWM controller the pin PWM_STOP can be connected to the output of the error amplifier
(
a
).
Figure 47.
Interface circuits that let the L6563H switch on or off a PWM controller
If the chip is provided with a soft-start pin, it is possible to delay the start-up of the dc-dc
stage with respect to that of the PFC stage, which is often desired, as described in
stage with respect to that of the PFC stage, which is often desired, as described in
. An underlying assumption in order for that to work properly is that the UVLO
thresholds of the PWM controller are certainly higher than those of the L6563H.
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