FSDM0365RL Fairchild Semiconductor, FSDM0365RL Datasheet - Page 13

• Manufacturer Part Number: FSDM0365RL
• Description: IC SWIT PWM GREEN CM OVP HV 8SOP
• Manufacturer: Fairchild Semiconductor

Specifications of FSDM0365RL

• Output Isolation: Isolated
• Frequency Range: 61 ~ 73kHz
• Voltage - Input: 8 ~ 20 V
• Voltage - Output: 650V
• Power (watts): 30W
• Operating Temperature: 25°C ~ 140°C
• Package / Case: 8-SOP, 8-LSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: FSDM0365RL_NL; FSDM0365RL_NL

4.2 Thermal Shutdown (TSD) : The Sense FET and the
control IC are integrated, making it easier for the control IC
to detect the temperature of the Sense FET. When the tem-
perature exceeds approximately 140°C, thermal shutdown is
activated.
4.3 Abnormal Over Current Protection (AOCP) :
Even though the FPS has OLP (Over Load Protection) and
current mode PWM feedback, these are not enough to pro-
tect the FPS when a secondary side diode short or a trans-
former pin short occurs. In addition to start-up, soft-start is
also activated at each restart attempt during auto-restart and
when restarting after latch mode is activated. The FPS has an
internal AOCP (Abnormal Over Current Protection) circuit
as shown in figure 7. When the gate turn-on signal is applied
to the power Sense FET, the AOCP block is enabled and
Vcc
OLP
8V
6V
3V
Vsense
Vfb
t
1 t
t
2
1
COM PARATOR
COM PARATOR
=
=
V
C
PW M
FPS switching
−
AOCP
AOCP
fb
RC
(
1
V
Figure 7. AOCP Function & Block
fb
1 (
t
Delay current (5uA) charges the Cfb
Figure 6. Over load protection
In
2 t
+
LEB
I
1 (
t
delay
) 2
−
−
V
V
(
R
(
t
t
) 1
)) 1
);
;
V
I
CLK
delay
(
t
) 1
S
=
R
=
5
3
uA
V
,
,
3 t
V
Q
R
1 (
t
=
+
2
8 .
t
) 2
K
−
Ω
V
,
C
(
t
Following Vcc
) 1
fb
Out Driver
=
=
3
4 t
C
V
fb
_
fig
Rsense
2 .
Drain
t
monitors the current through the sensing resistor. The volt-
age across the resistor is then compared with a preset AOCP
level. If the sensing resistor voltage is greater than the AOCP
level, pulse by pulse AOCP is triggered regardless of uncon-
trollable LEB time. Here, pulse by pulse AOCP stops Sense
FET within 350nS after it is activated.
4.4 Over Voltage Protection (OVP) : In case of malfunc-
tion in the secondary side feedback circuit, or feedback loop
open caused by a defect of solder, the current through the
opto-coupler transistor becomes almost zero. Then, Vfb
climbs up in a similar manner to the over load situation, forc-
ing the preset maximum current to be supplied to the SMPS
until the over load protection is activated. Because excess
energy is provided to the output, the output voltage may
exceed the rated voltage before the over load protection is
activated, resulting in the breakdown of the devices in the
secondary side. In order to prevent this situation, an over
voltage protection (OVP) circuit is employed. In general,
Vcc is proportional to the output voltage and the FPS uses
Vcc instead of directly monitoring the output voltage. If
V
mination of the switching operation. In order to avoid undes-
ired activation of OVP during normal operation, Vcc should
be properly designed to be below 19V.
5. Soft Start : The FPS has an internal soft start circuit that
increases the feedback voltage together with the Sense FET
current slowly after it starts up. The typical soft start time is
15msec, as shown in figure 8, where progressive increments
of Sense FET current are allowed during the start-up phase.
The pulse width to the power switching device is progres-
sively 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 volt-
age. It also helps to prevent transformer saturation and
reduce the stress on the secondary diode.
2.15A
0.98A
CC
Drain current
exceeds 19V, OVP circuit is activated resulting in ter-
[A]
1mS
15steps
Current limit
FSDL0365RN, FSDM0365RN
13
t