FSDM0565RWDTU Fairchild Semiconductor, FSDM0565RWDTU Datasheet - Page 13

• Manufacturer Part Number: FSDM0565RWDTU
• Description: IC SWIT PWM GREEN CM HV TO220F
• Manufacturer: Fairchild Semiconductor

Specifications of FSDM0565RWDTU

• Output Isolation: Isolated
• Frequency Range: 60 ~ 72kHz
• Voltage - Input: 8 ~ 20 V
• Voltage - Output: 650V
• Power (watts): 70W
• Operating Temperature: 25°C ~ 150°C
• Package / Case: TO-220-6 Full Pack Formed Leads
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: FSDM0565RWDTU_NL; FSDM0565RWDTU_NL

FSDM0565R
output voltage may exceed the rated voltage before the over
load protection is activated, resulting in the breakdown of the
Vo
devices in the secondary side. In order to prevent this
set
Vo
situation, an over voltage protection (OVP) circuit is
employed. In general, Vcc is proportional to the output
TM
voltage and the FPS
uses Vcc instead of directly
V
monitoring the output voltage. If V
exceeds 19V, an OVP
CC
FB
circuit is activated resulting in the termination of the
0.7V
switching operation. In order to avoid undesired activation of
0.5V
OVP during normal operation, Vcc should be designed to be
below 19V.
Ids
3.4 Thermal Shutdown (TSD) : The Sense FET and the
control IC are built in one package. This makes it easy for
the control IC to detect the heat generation from the Sense
Vds
FET. When the temperature exceeds approximately 150 C,
the thermal shutdown is activated.
time
TM
4. Soft Start : The FPS
has an internal soft start circuit
Switching
Switching
that increases PWM comparator inverting input voltage
disabled
disabled
T4
T2 T3
T1
together with the Sense FET current slowly after it starts up.
Figure 9. Waveforms of burst operation
The typical soft start time is 10msec, The pulse width to the
power switching device is progressively increased to
establish the correct working conditions for transformers,
inductors, and capacitors. The voltage on the output
capacitors is progressively increased with the intention of
smoothly establishing the required output voltage. It also
helps to prevent transformer saturation and reduce the stress
on the secondary diode during startup.
5. Burst operation : In order to minimize power dissipation
TM
in standby mode, the FPS
enters burst mode operation.
As the load decreases, the feedback voltage decreases. As
shown in figure 9, the device automatically enters burst
mode
when
the
feedback
voltage
drops
below
V
(500mV). At this point switching stops and the
BURL
output voltages start to drop at a rate dependent on standby
current load. This causes the feedback voltage to rise. Once
it passes V
(700mV) switching resumes. The feedback
BURH
voltage then falls and the process repeats. Burst mode
operation alternately enables and disables switching of the
power Sense FET thereby reducing switching loss in
Standby mode.
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