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OB2288
Highly Integrated Current Mode PWM Controller
GENERAL DESCRIPTION
OB2288 is a highly integrated current mode PWM
controller. With internal maximum 50% duty cycle
limit, it is very suitable to be used in large power
applications, especially in forward topology.
OB2288 offers comprehensive protection coverage
including Cycle-by-Cycle current limiting, internal
Power-On Soft Start, VDD Under Voltage Lockout
(UVLO), VDD Over Voltage Protection(OVP), VDD
Clamp, Gate Clamp, Over Load Protection(OLP),
Over Temperature Protection (OTP), Brownout
Protection (BOP). OB2288 also features protections
against pin open and short conditions on selected
pins.
Moreover, an internal 1-second restart timer prevents
permanent OLP latch when the supply of the
controller is provided by other DC sources. In
general applications where supply is self biased by
auxiliary winding, this restart timer will never be
triggered.
In OB2288, On-Bright proprietary frequency
shuffling technique together with soft switching
control at the totem pole gate drive output help to
lower the system design barrier to achieve good EMI
performance.
To meet the increasing stringent standby power
requirements at light or no load condition, On-Bright
proprietary “Extended Burst Mode” technology eases
the system design with high performance and without
compromise in audio noise.
OB2288 is offered in SOP-8 and DIP-8 packages.
FEATURES
Maximum 50% Duty Cycle Limit
AC Line Brownout Detection & Protection (BOP)
Latch-off Mode Fault Protection
Internal Restart Timer
All Pins Floating Protection and RI Short
Protection
Proprietary Extended Burst Mode Control For
Improved Efficiency and Minimum Standby
Power Design
Audio Noise Free Operation
External Programmable PWM Switching
Frequency
Built-in Frequency Shuffling for Better EMI
Internal Leading Edge Blanking
High Precision Reference Voltage for OTP and
Brownout Protection
Power-On Soft Start
Internal Synchronized Slope Compensation
1A Peak Current Drive Capability
APPLICATIONS
Offline AC/DC Converter for
LCD TV/PC Power Supplies
Open-Frame SMPS
TYPICAL APPLICATION
©On-Bright Electronics
-1-
Confidential
OB_DOC_DS_8800
Free Datasheet http://www.datasheetlist.com/

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OB2288
Highly Integrated Current Mode PWM Controller
GENERAL INFORMATION
Pin Configuration
The pin map of OB2288 in DIP8 and SOP8 package
is shown as below.
GND
1
8 GATE
FB 2
7 VDD
BO 3
RI 4
6 SENSE
5 RT
Ordering Information
Part Number Description
OB2288AP
DIP8, Pb-free in Tube
OB2288CP
SOP8, Pb-free in Tube
OB2288CPA
SOP8,Pb-free in Taping
Package Dissipation Rating
Package
DIP8
SOP8
RθJA (°C/W)
90
150
Absolute Maximum Ratings
Parameter
VDD Zener Clamp Voltage
(Vclamp)
VDD Zener Clamp Continuous
Current
BO Input Voltage
FB Input Voltage
SENSE Input Voltage
RT Input Voltage
RI Input Voltage
Min/Max Operating Junction
Temperature TJ
Min/Max Storage Temperature
Tstg
Lead Temperature (Soldering,
10secs)
Value
31 V
10 mA
-0.3 to 7V
-0.3 to 7V
-0.3 to 7V
-0.3 to 7V
-0.3 to 7V
-20 to 150 oC
-55 to 150 oC
260 oC
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.
OB2288 X X X
Highly Integrated Current Mode
PWM Controller
Package
A:DIP8
C:SOP8
Package Pb-free
P : Lead Free
Packing
Blank : Tube
A : Taping
©On-Bright Electronics
-2-
Confidential
OB_DOC_DS_8800
Free Datasheet http://www.datasheetlist.com/

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Marking Information
OB2288
Highly Integrated Current Mode PWM Controller
TERMINAL ASSIGNMENTS
Pin Num Pin Name
1 GND
2 FB
3 BO
4 RI
5 RT
6 SENSE
7 VDD
8 GATE
I/O Description
P Ground.
I Feedback input pin. PWM duty cycle is determined by voltage level at this
pin and current-sense signal level at Pin 6.
I/O Brownout detection pin. Detects line voltage through a resistor divider. If the
voltage at this pin drops below 1.05V and lasts 50ms, brownout is triggered
and PWM output will be disabled.
I Internal oscillator frequency setting pin. A resistor connected between RI
and GND sets the PWM frequency.
I Dual function pin. Either connected through a NTC resistor to GND for over
temperature shutdown control or used as latch shutdown control input.
I Current sense input pin. Connected to MOSFET current sensing resistor
node.
P DC power supply pin.
O Totem-pole gate drive output for power MOSFET.
©On-Bright Electronics
-3-
Confidential
OB_DOC_DS_8800
Free Datasheet http://www.datasheetlist.com/

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BLOCK DIAGRAM
OB2288
Highly Integrated Current Mode PWM Controller
RECOMMENDED OPERATING CONDITION
Symbol
VDD
RI
TA
Parameter
VDD Supply Voltage
RI Resistor Value
Operating Ambient Temperature
Min Max Unit
11.5 25
V
10 40 Kohm
-20 85
oC
©On-Bright Electronics
-4-
Confidential
OB_DOC_DS_8800
Free Datasheet http://www.datasheetlist.com/

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OB2288
Highly Integrated Current Mode PWM Controller
ELECTRICAL CHARACTERISTICS
(TA = 25OC, RI=20K ohm, VDD=16V, if not otherwise noted)
Symbol
Parameter
Test Conditions
Supply Voltage (VDD) Section
I_VDD_Startup VDD Startup Current VDD =13.5V
I_VDD_Ops
UVLO(Enter)
Operation Current
VDD Under Voltage
Lockout Enter
VFB=3V
UVLO(Exit)
VDD Under Voltage
Lockout Exit
OVP
VDD Over Voltage
Protection
TD_OVP
VDD OVP Debounce
Time
VDD_De-Latch Latch Release
Voltage Threshold
I_VDD_Latch
VDD Current at
Latch Shutdown
VDD=8V
VDD_Clamp
VDD Zener Clamp
Voltage
I(VDD ) = 15 mA
T_Softstart
Soft Start Time
Feedback Input Section(FB Pin)
AVCS
PWM Input Gain
VFB_Open
FB Pin Open Voltage
ΔVFB /ΔVcs
VDD=18V
Min Typ Max Unit
5 20 uA
2.3 mA
8 9 10 V
14.2 15.2 16.2 V
26 28 30 V
100 uSec
6.5 V
45 uA
31 V
4 mSec
2.2 V/V
6V
IFB_max
FB Pin Maximum
Source Current
VDD=18V, Short FB pin
to GND.
1.1
VFB_TH
Zero Duty Cycle
Threshold Voltage
VDD=9.5V, Vsense=0V 0.9 1
VTH_BM
Burst Mode FB
Threshold Voltage
1.6
VTH_PL
Power Limiting FB
Threshold Voltage
4.4
TD_PL
Power Limiting
Debounce Time
250
ZFB_IN
Input Impedance
6
Current Sense Input(Sense Pin) Section
T_blanking
Sense Input Leading VDD=18V
Edge Blanking Time
300
VTH_OC
Internal Current
Limiting Comparator
Threshold
0.67 0.7
TD_OC
Propagation delay to CL=1nF at GATE
GATE
70
Oscillator Section
FOSC Normal Oscillation
Frequency
F(shuffle)/Fosc Frequency Shuffling
Range
60 65
-4
F_shuffle
f_Temp
Frequency Shuffling
Cycling Frequency
Frequency
Temperature Stability
-20oC to 100 oC
32
3
mA
1.1 V
V
V
mSec
Kohm
nSec
0.73 V
nSec
70 KHz
4%
Hz
%
©On-Bright Electronics
-5-
Confidential
OB_DOC_DS_8800
Free Datasheet http://www.datasheetlist.co