SRM4010 Microsemi Commercial Components Group, SRM4010 Datasheet - Page 5

• Manufacturer Part Number: SRM4010
• Description: DIODE SYNC POWERMOD 40A SMD
• Manufacturer: Microsemi Commercial Components Group

Specifications of SRM4010

• Applications: Processor
• Operating Temperature: -40°C ~ 80°C
• Package / Case: SMD 1.83mm x 1.43mm
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Mounting Type: -
• Current - Supply: -
• Voltage - Supply: -

General Description
The SRM
loss rectifiers. The proprietary control ICs operate these
MOSFETs as synchronous rectifiers in circuit that maximizes
efficiency and eliminates cross conduction.
The SRM
powers the internal control circuitry and can also provide a
power source that can be used for external control circuitry. This
is especially useful in low voltage outputs where the output is
not high enough to power the secondary-side control directly for
the output
Continuous/Heavy Load Operation
Continuous conduction is the mode of operation where there is
always current flowing in the output inductor. This is the normal
mode of operation in most forward converters in medium to high
power applications.
During the conduction period (on-time) of the primary-side
Switch (usually a MOSFET), the Catch MOSFET in the module
is off and the current is flowing from the transformer to the
output inductor, output capacitor and the load. The load current
returns though the forward MOSFET to the negative secondary
terminal of the power transformer.
Copyright
2004-02-06
TM
TM
4010 contains two power MOSFETs that act as low
4010 has an internal 5 volt linear regulator that
2000
REV. 1
C O L O R A D O D I V I S I O N
800 Hoyt Street, Broomfield, CO. 80020, 303-469-2161, Fax: [phone]
SRM
TM
4010 Forward Converter Block Diagram
T H E O R Y O F O P E R A T I O N
T H E O R Y O F O P E R A T I O N
T H E O R Y O F O P E R A T I O N
T H E O R Y O F O P E R A T I O N
Colorado Division
Microsemi
Figure 6
The transformer voltage applied to the Catch MOSFET in the
module must be below the 20V maximum rating in this mode of
operation As the primary-side switch turns off, the transformer
current goes to zero and the voltage on Pin 1 of the module falls
to zero driven by the current stored in the output inductor. In this
mode, the current is carried through the Catch MOSFET body
diode momentarily, then the MOSFET is turned on allowing
reduced forward voltage drop. The time of body diode
conduction is very short, typically less than 50 nS. The
transformer voltage on Pin 2 goes positive, driven by the
transformer magnetizing current. This allows the transformer to
reset, keeping volt-second balance on the core
Since a transformer cannot support dc voltage, the area of the ON
time and the OFF time are equal. After reset the transformer
voltage actually changes sign causing a slight forward bias of the
body diode in the forward MOSFET. This voltage is typically
–0.5 volts, however, since there is almost no current flowing
during this time, there is no significant power loss. When the
primary-side switch turns on, the internal control circuitry turns
off the Catch MOSFET slightly before the rise of the voltage and
also turns on the forward MOSFET
40A Synchronous Rectifier Module
SRM
TM
4010
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