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DM07652R Schematic ( PDF Datasheet ) - Fairchild Semiconductor

Teilenummer DM07652R
Beschreibung FSDM07652R
Hersteller Fairchild Semiconductor
Logo Fairchild Semiconductor Logo 




Gesamt 20 Seiten
DM07652R Datasheet, Funktion
www.fairchildsemi.com
FSDM07652R
Green Mode Fairchild Power Switch (FPSTM)
Features
• Internal Avalanche Rugged Sense FET
• Advanced Burst-Mode operation consumes under 1 W at
240VAC & 0.5W load
• Precision Fixed Operating Frequency (66kHz)
• Internal Start-up Circuit
• Pulse by Pulse Current Limiting
• Abnormal Over Current Protection (AOCP)
• Over Voltage Protection (OVP)
• Over Load Protection (OLP)
• Internal Thermal Shutdown Function (TSD)
• Auto-Restart Mode
• Under Voltage Lock Out (UVLO) with hysteresis
• Low Operating Current (2.5mA)
Built-in Soft Start
OUTPUT POWER TABLE
230VAC ±15%(3)
85-265VAC
PRODUCT
Adapt- Open Adapt- Open
er(1) Frame(2) er(1) Frame(2)
FSDM0565R 60W
70W
50W
60W
FSDM07652R 70W
80W
60W
70W
Table 1. Notes: 1. Typical continuous power in a non-ven-
tilated enclosed adapter measured at 50°C ambient. 2.
Maximum practical continuous power in an open frame
design at 50°C ambient. 3. 230 VAC or 100/115 VAC with
doubler.
Application
• SMPS for LCD monitor and STB
• Adaptor
Description
The FSDM07652R is an integrated Pulse Width Modulator
(PWM) and Sense FET specifically designed for high
performance offline Switch Mode Power Supplies (SMPS)
with minimal external components. This device is an
integrated high voltage power switching regulator which
combine an avalanche rugged Sense FET with a current mode
PWM control block. The PWM controller includes integrated
fixed frequency oscillator, under voltage lockout, leading
edge blanking (LEB), optimized gate driver, internal soft
start, temperature compensated precise current sources for a
loop compensation and self protection circuitry. Compared
with discrete MOSFET and PWM controller solution, it can
reduce total cost, component count, size and weight simulta-
neously increasing efficiency, productivity, and system
reliability. This device is a basic platform well suited for cost
effective designs of flyback converters.
Typical Circuit
AC
IN
Vstr Drain
PWM
Vfb Vcc Source
Figure 1. Typical Flyback Application
DC
OUT
©2005 Fairchild Semiconductor Corporation
Rev.1.0.6






DM07652R Datasheet, Funktion
FSDM07652R
Shutdown delay current
TOTAL DEVICE SECTION
Operating supply current (5)
IDELAY VFB=5V
2.8 3.5 4.2 µA
IOP
IOP(MIN)
IOP(MAX)
VFB=GND, VCC=14V
VFB=GND, VCC=10V
VFB=GND, VCC=18V
- 2.5 5 mA
Notes:
1. Pulse test : Pulse width 300µS, duty 2%
2. These parameters, although guaranteed at the design, are not tested in mass production.
3. These parameters, although guaranteed, are tested in EDS(wafer test) process.
4. These parameters indicate the inductor current.
5. This parameter is the current flowing into the control IC.
6

6 Page









DM07652R pdf, datenblatt
FSDM07652R
Vds Power
on
Fault
occurs
Fault
removed
VFB
6.0V
Over load protection
2.5V
Vcc T12= Cfb*(6.0-2.5)/Idelay
12V T1 T2 t
8V Figure 7. Over load protection
t
Normal
operation
Fault
situation
Normal
operation
Figure 6. Auto restart operation
3.1 Over Load Protection (OLP) : Overload is defined as
the load current exceeding a pre-set level due to an
unexpected event. In this situation, the protection circuit
should be activated in order to protect the SMPS. However,
even when the SMPS is in the normal operation, the over
load protection circuit can be activated during the load
transition. In order to avoid this undesired operation, the over
load protection circuit is designed to be activated after a
specified time to determine whether it is a transient situation
or an overload situation. Because of the pulse-by-pulse
current limit capability, the maximum peak current through
the Sense FET is limited, and therefore the maximum input
power is restricted with a given input voltage. If the output
consumes beyond this maximum power, the output voltage
(Vo) decreases below the set voltage. This reduces the
current through the opto-coupler LED, which also reduces
the opto-coupler transistor current, thus increasing the
feedback voltage (Vfb). If Vfb exceeds 2.5V, D1 is blocked
and the 3.5uA current source starts to charge CB slowly up to
Vcc. In this condition, Vfb continues increasing until it
reaches 6V, when the switching operation is terminated as
shown in figure 7. The delay time for shutdown is the time
required to charge CB from 2.5V to 6.0V with 3.5uA. In
general, a 10 ~ 50 ms delay time is typical for most
applications.
3.2 Abnormal Over Current Protection (AOCP) : Even
though the FPSTM has OLP (Over Load Protection) and
current mode PWM feedback, these are not enough to protect
the FPSTM when a secondary side diode short or a
transformer pin short occurs. The FPSTM has an internal
AOCP (Abnormal Over Current Protection) circuit as shown
in figure 8. When the gate turn-on signal is applied to the
power Sense FET, the AOCP block is enabled and monitors
the current through the sensing resistor. The voltage across
the resistor is then compared with a preset AOCP level. If the
sensing resistor voltage is greater than the AOCP level for
longer than 300ns, the reset signal is applied to the latch,
resulting in the shutdown of SMPS.
2.5R
R
OSC
PWM
SQ
RQ
LEB
AOCP
Gate
driver
Rsense
Vaocp
2
GND
Figure 8. AOCP block
3.3 Over voltage Protection (OVP) : If the secondary side
feedback circuit were to malfunction or a solder defect
caused an open in the feedback path, the current through the
opto-coupler transistor becomes almost zero. Then, Vfb
climbs up in a similar manner to the over load situation,
forcing the preset maximum current to be supplied to the
SMPS until the over load protection is activated. Because
more energy than required is provided to the output, the
12

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