L6563S STMicroelectronics, L6563S Datasheet - Page 33

• Manufacturer Part Number: L6563S
• Description: IC PFC CTRLR TRANSITION 14SOIC
• Manufacturer: STMicroelectronics

Specifications of L6563S

• Mode: Discontinuous (Transition)
• Current - Startup: 90µA
• Voltage - Supply: 10.3 V ~ 22.5 V
• Operating Temperature: -40°C ~ 150°C
• Mounting Type: Surface Mount
• Package / Case: 14-SOIC
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Frequency - Switching: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

L6563S
Application information
Figure 45. Interface circuits for power up sequencing when dc-dc has the SS
function
If this is not the case or it is not possible to achieve a start-up delay long enough (because
this prevents the dc-dc stage from starting up correctly) or, simply, the PWM controller is
devoid of soft start, the arrangement of
Figure 46
lets the dc-dc converter start-up when the
voltage generated by the PFC stage reaches a preset value. The technique relies on the
UVLO thresholds of the PWM controller.
Figure 46. Interface circuits for actual power-up sequencing (master PFC)
Another possible use of the RUN and PWM_STOP pins (again, in systems where the PFC
stage is the master) is the brownout protection, thanks to the hysteresis provided.
The brownout protection is basically a not-latched device shutdown function that is activated
when a condition of mains undervoltage is detected. This condition may cause overheating
of the primary power section due to an excess of RMS current. Brownout can also cause the
PFC pre-regulator to work open loop and this could be dangerous to the PFC stage itself
and the downstream converter, should the input voltage return abruptly to its rated value.
Another problem is the spurious restarts that may occur during converter power down and
that cause the output voltage of the converter not to decay to zero monotonically. For these
reasons it is usually preferable to shutdown the unit in case of brownout.
IC shutdown upon brownout can be easily realized as shown in
Figure 47
. The scheme on
the left is of general use, that one on the right can be used if the bias levels of the multiplier
and the R
·C
time constant are compatible with the specified brownout level and with the
FF
FF
specified holdup time respectively. In this latest case, an additional resistor voltage divider
and one capacitor are not needed.
Doc ID 16116 Rev 4
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