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OB2298
PWM Controller with PFC Standby Control
GENERAL DESCRIPTION
OB2298 is a highly integrated current mode PWM
controller for medium to high power offline flyback
converter applications.
OB2298 integrates PFC IC power supply control
function and shuts down PFC stage at no load or light
load conditions.
To meet the increasing stringent standby power
requirements in light or zero load, OB2298 operates
in On-Bright’s proprietary “extended burst mode”
without audio noise. Constant power limit is achieved
by On-Bright’s proprietary OCP compensation
technique where OCP due to CCM and DCM mode
difference is compensated in universal AC input
applications.
OB2298 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),
Programmable Brownout Protection, All Pins
Floating Protection, and RT Latch triggering feature.
In applications where VDD is supplied by auxiliary
power supply, the built-in 1 second restart timer can
prevent permanent OLP latch. In other applications,
this restart timer will not be triggered.
To achieve good EMI performance, On-Bright’s
proprietary built-in frequency shuffling is provided,
also with soft switching control at the totem pole gate
drive output.
OB2298 is offered in SOP-8 and DIP-8 packages.
FEATURES
Direct Control of PFC
Programmable Brownout Protection
Internal 4ms Power On Soft Start Time
Internal Restart Timer
Pin Floating Protection
Proprietary Extended Burst Mode Control For
Improved Efficiency and Minimum Standby
Power Design
Built-in Frequency Shuffling for Better EMI
Built-in Leading Edge Blanking
Proprietary OCP Compensation for Universal AC
Input Range
Low Startup Current(5uA) and Low Operating
Current (2.3mA)
Built-in Synchronized Slope Compensation
1.0A Peak Current Driving Capability
Audio Noise Free Operation
Convenient High and Low Triggering Level
Latch Off Function
APPLICATIONS
Offline AC/DC flyback converter for
Laptop Power Adaptor
LCD Monitor Power
LCD TV Power and Home Appliance Power
Printer Power
Lighting Power
TYPICAL APPLICATION
©On-Bright Electronics
-1-
Confidential
OB_DOC_DS_9800
Free Datasheet http://www.datasheet4u.com/

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OB2298
PWM Controller with PFC Standby Control
GENERAL INFORMATION
Pin Configuration
The pin map of OB2298 in DIP8 and SOP8 package
is shown as below.
PFCVCC 1
8 VDD
BO 2
7 GATE
RT 3
6 GND
FB 4
5 CS
Ordering Information
Part Number
OB2298AP
Description
DIP8, Pb-free
OB2298CP
SOP8, Pb-free
OB2298CPA
SOP8, Pb-free in Taping
.
Package Dissipation Rating
Package
DIP8
SOP8
RθJA (°C/W)
90
150
Absolute Maximum Ratings
Parameter
VDD Zener Clamp Voltage
VDD Clamp Continuous
Current
BO Input Voltage
RT Input Voltage
FB Input Voltage
CS Input Voltage
Min/Max Operating Junction
Temperature TJ
Min/Max Storage Temperature
Tstg
Lead Temperature (Soldering,
10secs)
Value
30 V
10 mA
-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.
©On-Bright Electronics
-2-
Confidential
OB_DOC_DS_9800
Free Datasheet http://www.datasheet4u.com/

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Marking Information
OB2298
PWM Controller with PFC Standby Control
TERMINAL ASSIGNMENTS
Pin Num Pin Name
1 PFCVCC
2 BO
3 RT
4 FB
5 CS
6 GND
7 GATE
8 VDD
I/O Description
P This pin is directly connected to the VDD pin (Pin 8) via a low impedance
switch. During the startup sequence, the switch is off thus the power supply
to PFC stage. As soon as the aux. winding is stabilized. The switch is on and
provides power supply to the PFC controller. It goes down at No/Light load
or fault conditions.
I/O Connected a resistor divider from line voltage to this pin to detect line
voltage. If this pin drops below 1.05V and lasts 100ms, PWM output will be
disabled. When brownout is triggered, this pin will disable an internal
current for brownout hysteresis programming.
I Temperature sensing input pin. Connected to a NTC resistor to GND.
Once the voltage of the RT pin drops below a fixed limit of 1.05V, PWM
output will be disabled. When this pin is above 4.0V or below 0.6V, the
PWM controller is latched shutdown.
I Feedback input pin. PWM duty cycle is determined by the voltage level into
this pin and current sense signal level at Pin 5.
I Current sense input pin. Connected to MOSFET current sensing resistor
node.
P Ground
O Totem-pole gate drive output for power MOSFET.
P DC power supply pin.
©On-Bright Electronics
-3-
Confidential
OB_DOC_DS_9800
Free Datasheet http://www.datasheet4u.com/

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BLOCK DIAGRAM
OB2298
PWM Controller with PFC Standby Control
RECOMMENDED OPERATING CONDITION
Symbol
VDD
TA
Parameter
VDD Supply Voltage
Operating Ambient Temperature
Min Max Unit
12 25 V
-20 85
oC
©On-Bright Electronics
-4-
Confidential
OB_DOC_DS_9800
Free Datasheet http://www.datasheet4u.com/

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OB2298
PWM Controller with PFC Standby Control
ELECTRICAL CHARACTERISTICS
(TA = 25OC, VDD=18V, if not otherwise noted)
Symbol
Parameter
Supply Voltage (VDD) Section
Istartup
VDD start up current
I_VDD
UVLO(ON)
UVLO(OFF)
OVP(Latch)
VDD(De-Latch)
Ivdd_latch
TD_OVP
VDD_Clamp
T_Softstart
Operation current
VDD under voltage
lockout enter
VDD under voltage
lockout exit (Startup)
VDD over voltage
latch trigger
VDD latch release
threshold voltage
VDD bleeding
current at latch
shutdown
VDD OVP Debounce
time
VDD zener clamp
voltage
Soft start time
Feedback Input Section(FB Pin)
AVCS
PWM input gain
VFB_Open
FB open voltage
Test Conditions
VDD =14V, Measure
current into VDD
VFB=3V
VDD=8V
I(VDD ) = 10 mA
VFB /Vcs
IFB_Short
VTH_0D
VTH_GM
VTH_BM_on
VTH_BM_off
VTH_PL
TD_PL
ZFB_IN
VTH_PFC_off
VTH_PFC_on
FB pin short circuit
current
Zero duty cycle FB
threshold voltage
Green mode FB
threshold voltage
Burst mode on FB
threshold voltage
Burst mode off FB
threshold voltage
Power limiting FB
threshold voltage
Power limiting
debounce time
Input impedance
PFC off FB threshold
voltage
PFC on FB threshold
voltage
Current Sense Input(CS Pin) Section
T_blanking
CS input leading
edge blanking time
VTH_OC
Internal current
limiting threshold
Short FB pin to GND,
measure current
Zero duty cycle
©On-Bright Electronics
-5-
Min Typ Max Unit
5 20 uA
2.3 mA
8 9 10 V
14.5 15.5 16.5 V
26 28 30 V
6.5 V
45 uA
100
30
4
2.4
5.5
1.1
1
1.7
1.3
1.4
4.4
225
5
1.6
1.7
uSec
V
mSec
V/V
V
mA
V
V
V
V
V
mSec
Kohm
V
V
300
0.57 0.6
nSec
0.63 V
Confidential
OB_DOC_DS_9800
Free Datasheet http://www.datasheet4u.com/