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On-Bright Electronics Co., Ltd.
0755-82584090/83587431
OB2301W
High Performance synchronous rectifier
GENERAL DESCRIPTION
OB2301W is a high performance and tightly
integrated secondary side synchronous rectifier for
switch mode power supply system. It combines a
much lower voltage drop N-channel MOSFET to
emulate the traditional diode rectifier at the
secondary side of Flyback converter, which can
reduce heat dissipation, increases output current
capability and efficiency and simplify thermal
design. OB2301W can support low system output
voltage down to 2V at constant current mode.
It is suitable for multiple mode applications
including discontinuous conduction mode and
quasi-resonant mode. With its versatility and
optimization, OB2301W can be used in various
switch mode power supply topologies including
secondary-side control topology and primary-side
control topology.
From the information on the secondary side of the
isolation transformer, OB2301W generates a
driving signal with dead time with respect to the
primary side PWM signal to turn the integrated N-
channel SR switch on and off in proximity of the
zero current transition with the help of smart driver
voltage control. It is optimized for 5V output
voltage. In primary-side control topology,
OB2301W can detect the output voltage and feed
back a series of warning pulses to primary side
controller when the output voltage is lower than an
inner-determined threshold to awaken the primary-
side power switch to improve dynamic response.
The externally adjustable minimum on time and
property off time control scheme effectively avoid
the ring impact induced by parasitic elements so
that a reliable and noise free operation of the SR
system is insured.
OB2301W is offered in SOP8 package.
FEATURES
Secondary-side synchronous rectifier
optimized for 5V output system
Suitable for DCM, QR operation
Accurate secondary side MOSFET Vds
sensing
Low cost small size CC/CV mode support
Up to 200kHz operation frequency
3A/2A peak current sink/source driver
capability
Output voltage over-shoot and under-shoot
control
Enhanced dynamic response with firing
warning pulses scheme
VDD UVLO protection
APPLICATIONS
AC/DC 5V adaptors
Cell phone charger
5V Bias supply
Low voltage rectification circuits
TYPICAL APPLICATION
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1
Preliminary Datasheet
OB_DOC_DS_2301W01

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On-Bright Electronics Co., Ltd.
0755-82584090/83587431
OB2301W
WHigh Performance Synchronous Rectifier
GENERAL INFORMATION
Pin Configuration
The OB2301W is offered in SOP8 package,
shown as below.
Ordering Information
Part Number
OB2301WCP
Description
SOP8, Pb-free in Tube
OB2301WCPA
SOP8, Pb-free in T&R
Package Dissipation Rating
Package
RJA(/W)
SOP8
90
Absolute Maximum Ratings
Parameter
Vin pin
VDD pin
VD pin
VS pin
RT pin
Drain pin
Min/Max
Operating
Junction Temperature TJ
Value
-0.6V to 7V
-0.6V to 7V
-0.6V to 50V
-0.6V to 7V
-0.6V to 7V
-0.6V to BVdss
-40 to 150
Operating
Ambient
Temperature TA
Min/Max
Storage
Temperature Tstg
-40 to 85
-55 to 150
Lead
Temperature
(Soldering, 10secs)
260
Note: Stresses beyond those listed under “absolute
maximum ratings” may cause permanent damage to the device.
These are stress ratings only, functional operation of the device
at these or any other conditions beyond those indicated under
“recommended operating conditions” is not implied. Exposure
to absolute maximum-rated conditions for extended periods
may affect device reliability.
Recommended Operating Range
Symbol Parameter
Min/Max
VDD
VDD Supply Voltage 4V to 5.5V
OB2301W X
X
X
High Performance Synchronous
Rectifier
Package
C:SOP8
Package Pb-free
P:Pb-free
Packing
Blank:Tube
A: Tape/Reel
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Preliminary Datasheet
OB_DOC_DS_2301W01

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On-Bright Electronics Co., Ltd.
0755-82584090/83587431
Marking Information
OB2301W
WHigh Performance Synchronous Rectifier
YWWZZZ
OB2301WCP
S
Y:Year Code
WW:Week Code(01-52)
ZZZ:Lot Code
C:SOP8 Package
P:Pb-free Package
S:Internal Code(Optional)
TERMINAL ASSIGNMENTS
Pin Name
VS
VD
Drain
GND
VDD
Vin
RT
I/O Description
I This pin is connected to external n-channel MOSFET source
I This pin is connected to external n-channel MOSFET drain
I/O SR Mosfet drain pin. This pin is connected to secondary-side winding of transformer
P Ground.
P Power Supply
I System output voltage detection
O Minimum on time control pin. A resistor is connected from this pin to GND
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Preliminary Datasheet
OB_DOC_DS_2301W01

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On-Bright Electronics Co., Ltd.
0755-82584090/83587431
BLOCK DIAGRAM
OB2301W
WHigh Performance Synchronous Rectifier
©On-Bright Electronics
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Preliminary Datasheet
OB_DOC_DS_2301W01

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On-Bright Electronics Co., Ltd.
0755-82584090/83587431
OB2301W
WHigh Performance Synchronous Rectifier
ELECTRICAL CHARACTERISTICS
(TA = 25, VDD=5V, unless otherwise noted)
Symbol
Parameter
Test Conditions
Min Typ Max Unit
Supply Voltage (VDD)
I_VDD_operation Operation current
Frequency@Vd=65KHz,VD
D=5V,1nF Cap load at
GATE.
Frequency@Vd=2KHz,VDD
=5V,No load at GATE.
1.5 2.0 mA
0.5 0.7 mA
Vdd_regulation_mini
Minimum
voltage
Vdd
regulation
4.2 V
UVLO(ON)
VDD Under Voltage Lockout
Entry
2.8 3.0 3.2 V
UVLO(OFF)
VDD Under Voltage Lockout
Exit (Recovery)
2.9 3.1 3.3 V
VD Detection Section
Vth_SR_act
SR MOSFET turn on threshold
voltage detection at VD
-350
mV
Vth_SR_deact
SR MOSFET turn off threshold
voltage detection at Vd
-5 mV
Tdelay_on
SR MOSFET
propagation delay
turn-on
100 ns
Tdelay_off
SR MOSFET
propagation delay
turn-off
75 ns
T_minimum_on
SR MOSFET minimum on time RT=25K
1.9 Us
RT Section
Vrt Voltage reference at RT pin
Over/Under Shoot Control Section
Vo_delta
Output delta variation in system
output undershoot control
Vo_delta_enb
Output delta variation detection
enable voltage
Fsample
Output delta variation detection
Sample frequency
Vo_low_clamp
Vo_High_clamp
IVo_High_clamp
Dsr_pulse
Fsw
Tdelay
System output undershoot
clamp control trigger voltage
System output overshoot clamp
control trigger voltage
System output overshoot clamp
current
Warning signal pulse width
when
system
output
undershoot is detected
Warning signal frequency when
system output undershoot is
detected
Warning signal blanking time
after
secondary-side
0.95 1 1.05 V
160 mV
5.25 V
15 KHz
4.5 4.6 4.7 V
5.8 V
70 mA
800 nS
27 30 33 KHz
65 us
©On-Bright Electronics
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Preliminary Datasheet
OB_DOC_DS_2301W01