FSL156MRIN
Green-Mode Fairchild Power Switch (FPS™)
FSL156MRIN — Green-Mode Fairchild Power Switch (FPS™)
June 2012
Features
Advanced Soft Burst Mode for Low Standby Power
and Low Audible Noise
Random Frequency Fluctuation (RFF) for Low EMI
Pulse-by-Pulse Current Limit
Overload Protection (OLP), Over-Voltage
Protection (OVP), Abnormal Over-Current
Protection (AOCP), Internal Thermal Shutdown
(TSD) with Hysteresis, Output-Short Protection
(OSP), and Under-Voltage Lockout (UVLO) with
Hysteresis , Line Over Voltage Protection (LOVP)
The FSL156MRIN is an integrated Pulse Width
Modulation (PWM) controller and SenseFET specifically
designed for offline Switched Mode Power Supplies
(SMPS) with minimal external components. The PWM
controller includes an integrated fixed-frequency
oscillator, Line-Over Voltage Protection (LOVP), UnderVoltage Lockout (UVLO), Leading-Edge Blanking (LEB),
optimized gate driver, internal soft-start, temperaturecompensated precise current sources for loop
compensation, and self-protection circuitry. Compared
with a discrete MOSFET and PWM controller solution,
the FSL156MRIN reduces total cost, component count,
size, and weight; while simultaneously increasing
efficiency, productivity, and system reliability. This
device provides a basic platform suited for cost-effective
design of a flyback converter.
Ordering Information
Output Power Table
Operating
Part Number
Package
(1)
Junction
Temperature
FSL156MRIN
Notes:
1. Lead-free package per JEDEC J-STD-020B.
2. The junction temperature can limit the maximum output power.
3. Typical continuous power in a non-ventilated enclosed adapter measured at 50C ambient temperature.
4. Maximum practical continuous power in an open-frame design at 50C ambient temperature.
FSL156MRIN — Green-Mode Fairchild Power Switch (FPS™)
1. GND
2. V
CC
FSL156MRIN
3. FB
4. V
IN
Figure 3. Pin Assignments (Top View)
Pin Definitions
Pin # Name Description
1 GND
2 V
3 FB
4 V
5 V
6
7
Drain
8
Ground. This pin is the control ground and the SenseFET source.
Power Supply. This pin is the positive supply input, which provides the internal operating
CC
current for both startup and steady-state operation.
Feedback. This pin is internally connected to the inverting input of the PWM comparator.
The collector of an opto-coupler is typically tied to this pin. For stable operation, a capacitor
should be placed between this pin and GND. If the voltage of this pin reaches 7V, the
overload protection triggers, which shuts down the FPS.
Line Over-Voltage Input. This pin is the input pin of line voltage. The voltage, which is
divided by resistors, is the input of this pin. If this pin voltage is higher than V
IN
LOVP triggers, which shuts down the FPS. Do not leave this pin floating. If LOVP is not used,
this pin should be directly connected to the GND.
Startup. This pin is connected directly, or through a resistor, to the high-voltage DC link.
At startup, the internal high-voltage current source supplies internal bias and charges the
STR
external capacitor connected to the V
source (I
SenseFET Drain. High-voltage power SenseFET drain connection.
FSL156MRIN — Green-Mode Fairchild Power Switch (FPS™)
Absolute Maximum Ratings
Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be
operable above the recommended operating conditions and stressing the parts to these levels is not recommended.
In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability.
The absolute maximum ratings are stress ratings only.
Symbol Parameter Min. Max. Unit
V
V
STR
VDS Drain Pin Voltage 650 V
V
V
CC
V
Feedback Pin Voltage -0.3 10.0 V
FB
VIN VIN Pin Voltage -0.3 10.0 V
I
Drain Current Pulsed 4 A
DM
I
Continuous Switching Drain Current
DS
EAS Single-Pulsed Avalanche Energy
PD
T
J
T
Storage Temperature -55 +150
STG
ESD
Notes:
5. Repetitive peak switching current when the inductive load is assumed: limited by maximum duty (D
junction temperature (see Figure 4).
6. L=45mH, starting T
7. Infinite cooling condition (refer to the SEMI G30-88).
8. Although this parameter guarantees IC operation, it does not guarantee all electrical characteristics.
Pin Voltage 650 V
STR
Pin Voltage 26 V
CC
1.90
1.27
1.5 W
Total Power Dissipation (T
=25C)
C
T
=25C
(5)
C
TC=100C
(6)
190 mJ
(7)
Maximum Junction Temperature 150
Operating Junction Temperature
Electrostatic Discharge
Capability
=25C.
J
Human Body Model, JESD22-A114
Charged Device Model, JESD22-C101
(8)
-40 +125
4.5
2.0
MAX
A
C
C
C
kV
=0.73) and
Figure 4. Repetitive Peak Sw itching Current
Thermal Impedance
TA=25°C unless otherwise specified.
Symbol Parameter Value Unit
JA Junction-to-Ambient Thermal Impedance
JL Junction-to-Lead Thermal Impedance
Notes:
9. JEDEC recommended environment, JESD51-2, and test board, JESD51-10, with minimum land pattern.
10. Measured on drain pin #7, close to the plastic interface.
1. Startup: At startup, an internal high-voltage current
source supplies the internal bias and charges the
external capacitor (C
illustrated in Figure 19. When V
FSL156MRIN begins switching and the internal highvoltage current source is disabled. Normal switching
operation continues and the power is supplied from the
auxiliary transformer winding unless VCC goes below the
stop voltage of 7.5V.
Figure 19. Startup Block
2. Soft-Start: The internal soft-start circuit increases
PWM comparator inverting input voltage, together with
the SenseFET current, slowly after startup. The typical
soft-start time is 15ms. The pulse width to the power
switching device is progressively increased to establish
the correct working conditions for the transformers,
inductors, and capacitors. The voltage on the output
capacitors is progressively increased to smoothly
establish the required output voltage. This helps prevent
transformer saturation and reduces stress on the
secondary diode during startup.
) connected to the VCC pin, as
VCC
reaches 12V, the
CC
3. Feedback Control: This device employs Current-
Mode control, as shown in Figure 20. An opto-coupler
(such as the FOD817) and shunt regulator (such as the
KA431) are typically used to implement the feedback
network. Comparing the feedback voltage with the
voltage across the R
resistor makes it possible to
SENSE
control the switching duty cycle. When the reference pin
voltage of the shunt regulator exceeds the internal
reference voltage of 2.5V, the opto-coupler LED current
increases, pulling down the feedback voltage and
reducing drain current. This typically occurs when the
input voltage is increased or the output load is decreased.
3.1 Pulse-by-Pulse Current Limit: Because Current-
Mode control is employed, the peak current through
the SenseFET is limited by the inverting input of PWM
comparator (V
*), as shown in Figure 20. Assuming
FB
that the 90A current source flows only through the
internal resistor (3R + R =25k), the cathode voltage
of diode D2 is about 2.8V. Since D1 is blocked when
the feedback voltage (V
) exceeds 2.8V, the
FB
maximum voltage of the cathode of D2 is clamped at
this voltage. Therefore, the peak value of the current
through the SenseFET is limited.
3.2 Leading-Edge Blanking (LEB): At the instant the
internal SenseFET is turned on, a high-current spike
usually occurs through the SenseFET, caused by
primary-side capacitance and secondary-side rectifier
reverse recovery. Excessive voltage across the R
SENSE
resistor leads to incorrect feedback operation in
Current-Mode PWM control. To counter this effect, the
LEB circuit inhibits the PWM comparator for t
(300ns) after the SenseFET is turned on.
FSL156MRIN — Green-Mode Fairchild Power Switch (FPS™)
4. Protection Circuits: The FSL156MRIN has several
self-protective functions, such as Overload Protection
(OLP), Abnormal Over-Current Protection (AOCP),
Output-Short Protection (OSP), Over-Voltage Protection
(OVP), and Thermal Shutdown (TSD). All the
protections are implemented as auto-restart. Once the
fault condition is detected, switching is terminated and
the SenseFET remains off. This causes V
B
When V
B falls to the Under-Voltage Lockout (UVLO)
CC
to fall.
CC
stop voltage of 7.5V, the protection is reset and the
startup circuit charges the V
capacitor. When VCC
CC
reaches the start voltage of 12.0V, normal operation
resumes. If the fault condition is not removed, the
SenseFET remains off and V
drops to stop voltage
CC
again. In this manner, the auto-restart can alternately
enable and disable the switching of the power
SenseFET until the fault condition is eliminated.
Because these protection circuits are fully integrated
into the IC without external components, reliability is
improved without increasing cost.
Figure 21. Auto-Restart Protection Waveforms
4.1 Overload Protection (OLP): Overload is defined
as the load current exceeding its normal level due to
an unexpected abnormal event. In this situation, the
protection circuit should trigger to protect the SMPS.
However, even when the SMPS is in normal
operation, the overload protection circuit can be
triggered during the load transition. To avoid this
undesired operation, the overload protection circuit is
designed to trigger only after a specified time to
determine whether it is a transient situation or a true
overload situation. Because of the pulse-by-pulse
current-limit capability, the maximum peak current
through the SenseFET is limited and, therefore, the
maximum input power is restricted with a given input
voltage. If the output consumes more than this
maximum power, the output voltage (V
) decreases
OUT
below the set voltage. This reduces the current
through the opto-coupler LED, which also reduces the
opto-coupler transistor current, increasing the
feedback voltage (VFB). If VFB exceeds 2.5V, D1 is
blocked and the 2.0µA current source starts to charge
CFB slowly up. In this condition, VFB continues
increasing until it reaches 7.0V, when the switching
operation is terminated, as shown in Figure 22. The
delay for shutdown is the time required to charge C
from 2.5V to 7.0V with 2.0µA. A 25 ~ 50ms delay is
typical for most applications. This protection is
implemented as auto-restart.
Figure 22. Overload Protection
4.2 Abnormal Over-Current Protection (AOCP):
When the secondary rectifier diodes or the
transformer pins are shorted, a steep current with
extremely high di/dt can flow through the SenseFET
during the minimum turn-on time. Even though the
FSL156MRIN has overload protection, it is not
enough to protect the FSL156MRIN in that abnormal
case; due to the severe current stress imposed on the
SenseFET until OLP is triggered. The internal AOCP
circuit is shown in Figure 23. When the gate turn-on
signal is applied to the power SenseFET, the AOCP
block is enabled and monitors the current through the
sensing resistor. The voltage across the resistor is
compared with a preset AOCP level. If the sensingresistor voltage is greater than the AOCP level, the
set signal is applied to the S-R latch, resulting in the
shutdown of the SMPS.
Figure 23. Abnormal Over-Current Protection
FSL156MRIN — Green-Mode Fairchild Power Switch (FPS™)
4.3. Output-Short Protection (OSP): If the output is
shorted, steep current with extremely high di/dt can
flow through the SenseFET during the minimum turnon time. Such a steep current creates high-voltage
stress on the drain of the SenseFET when turned off.
To protect the device from this abnormal condition,
OSP is included. It is comprised of detecting V
SenseFET turn-on time. When the V
is higher than
FB
FB
2.0V and the SenseFET turn-on time is lower than
1.0s, this condition is recognized as an abnormal
error and PWM switching shuts down until V
reaches V
again. An abnormal condition output
START
short is shown in Figure 24.
and
CC
4.6 Line Over-Voltage Protection (LOVP): If the line
input voltage is increased to an unwanted level, high
line input voltage creates high-voltage stress on the
entire system. To protect from this abnormal condition,
LOVP is included. It is comprised of detecting V
divided resistors. When V
is higher than 1.95V, this
IN
condition is recognized as an abnormal error and PWM
switching shuts down until VIN decreases to around
1.89V (60mV hysteresis).
using
IN
FSL156MRIN — Green-Mode Fairchild Power Switch (FPS™)
Figure 25. Line Over-Voltage Protection
Figure 24. Output-Short Protection
4.4 Over-Voltage Protection (OVP): If the
secondary-side feedback circuit malfunctions or a
solder defect causes an opening in the feedback path,
the current through the opto-coupler transistor
becomes almost zero. Then VFB climbs up in a similar
manner to the overload situation, forcing the preset
maximum current to be supplied to the SMPS until the
overload protection is triggered. Because more
energy than required is provided to the output, the
output voltage may exceed the rated voltage before
5. Soft Burst Mode: To minimize power dissipation in
Standby Mode, the FSL156MRIN enters Burst-Mode
operation. As the load decreases, the feedback voltage
decreases. As shown in Figure 22, the device
automatically enters Burst Mode when the feedback
voltage drops below V
(350mV). At this point,
BURL
switching stops and the output voltages start to drop at
a rate dependent on standby current load. This causes
the feedback voltage to rise. Once it passes V
BURH
(500mV), switching resumes. The feedback voltage then
falls and the process repeats. Burst Mode alternately
enables and disables SenseFET switching, reducing
switching loss in Standby Mode.
the overload protection is triggered, resulting in the
breakdown of the devices in the secondary side. To
prevent this situation, an OVP circuit is employed. In
general, the V
and the FSL156MRIN uses V
monitoring the output voltage. If V
is proportional to the output voltage
CC
instead of directly
CC
exceeds 24.5V,
CC
an OVP circuit is triggered, resulting in the termination
of the switching operation. To avoid undesired
activation of OVP during normal operation, V
should
CC
be designed to be below 24.5V.
4.5 Thermal Shutdown (TSD): The SenseFET and
the control IC on a die in one package makes it easier
for the control IC to detect the temperature of the
SenseFET. If the temperature exceeds ~135C, the
thermal shutdown is triggered and stops operation.
The FSL156MRIN operates in Auto-Restart Mode
until the temperature decreases to around 75C,
when normal operation resumes.
6. Random Frequency Fluctuation (RFF): Fluctuating
switching frequency of an SMPS can reduce EMI by
spreading the energy over a wide frequency range. The
amount of EMI reduction is directly related to the
switching frequency variation, which is limited internally.
The switching frequency is determined randomly by
external feedback voltage and an internal free-running
oscillator at every switching instant. RFF effectively
scatters EMI noise around typical switching frequency
(67kHz) and can reduce the cost of the input filter
included to meet the EMI requirements (e.g. EN55022).
FSL156MRIN — Green-Mode Fairchild Power Switch (FPS™)
FSL156MRIN — Green-Mode Fairchild Power Switch (FPS™)
9.83
9.00
6.67
6.096
8.255
7.61
3.60
3.00
3.683
3.20
0.356
0.20
5.08 MAX
0.33 MIN
(0.56)
2.54
0.56
0.355
1.65
1.27
7.62
NOTES: UNLESS OTHERWISE SPECIFIED
A) THIS PACKAGE CONFORMS TO
JEDEC MS-001 VARIATION BA
B) ALL DIMENSIONS ARE IN MILLIMETERS.
C) DIMENSIONS ARE EXCLUSIVE OF BURRS,
MOLD FLASH, AND TIE BAR EXTRUSIONS.
D) DIMENSIONS AND TOLERANC
ES PER
ASME Y14.5M-1994
E) DRAWING FILENAME AND REVSION: MKT-N08FREV2.
7.62
9.957
7.87
Figure 28. 8-Lead, MDIP, JEDEC MS-001, .300" Wide
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