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OB2268 Schematic ( PDF Datasheet ) - Liteon

Teilenummer OB2268
Beschreibung (OB2268 / OB2269) Current Mode PWM Controller
Hersteller Liteon
Logo Liteon Logo 



Gesamt 12 Seiten
		
OB2268 Datasheet, Funktion
GENERAL DESCRIPTION
OB2268/9 is a highly integrated current mode PWM
control IC optimized for high performance, low
standby power and cost effective offline flyback
converter applications in above 20W power level.
PWM switching frequency at normal operation is
externally programmable and trimmed to tight range.
At no load or light load condition, the IC operates in
extended ‘burst mode’ to minimize switching loss.
Lower standby power and higher conversion
efficiency is thus achieved.
www.DataSheVet4DUD.colmow startup current and low operating current
contribute to a reliable power on startup design with
OB2268/9. A large value resistor could thus be used
in the startup circuit to minimize the standby power.
The internal slope compensation improves system
large signal stability and reduces the possible sub-
harmonic oscillation at high PWM duty cycle output.
Leading-edge blanking on current sense input
removes the signal glitch due to snubber circuit diode
reverse recovery. and greatly reduces the external
component count and system cost in the design.
OB2268/9 offers complete protection coverage with
automatic self-recovery feature including Cycle-by-
Cycle current limiting (OCP), over load protection
(OLP), over temperature protection (OTP), VDD
over voltage protection (OVP) and under voltage
lockout (UVLO). The Gate-drive output is clamped
to maximum 18V to protect the power MOSFET.
Excellent EMI performance is achieved with On-
Bright proprietary frequency shuffling technique
(OB2269 only) together with soft switching control at
the totem pole gate drive output.
The tone energy at below 20KHZ is minimized in
operation. Consequently, audio noise performance is
greatly improved.
OB2268
OB2269
Current Mode PWM Controller
OB2268/9 is offered in SOP-8 and DIP-8 packages.
FEATURES
Extended Burst Mode Control For Improved
Efficiency and Minimum Standby Power Design
Audio Noise Free Operation
External Programmable PWM Switching
Frequency
Internal Synchronized Slope Compensation
Low VIN/VDD Startup Current(4uA) and Low
Operating Current (2.3mA)
Leading Edge Blanking on Current Sense Input
Complete Protection Coverage With Auto Self-
Recovery
o External Programmable Over Temperature
Protection (OTP)
o With or Without On-chip VDD OVP for
Output Over Voltage Protection.
o Under Voltage Lockout with Hysteresis
(UVLO)
o Gate Output Maximum Voltage Clamp (18V)
o Line Compensated Cycle-by-Cycle Over-
current Threshold Setting For Constant Output
Current Limiting Over Universal Input Voltage
Range (OCP)
o Over Load Protection. (OLP)
On-Bright Proprietary Frequency Shuffling
Technology for Improved EMI Performance
(OB2269 only)
APPLICATIONS
Offline AC/DC flyback converter for
Laptop Power Adaptor
PC/TV/Set-Top Box Power Supplies
Open-frame SMPS
Battery Charger
TYPICAL APPLICATION
©On-Bright Electronics
A Liteon Semiconductor Company
-1-
Confidential
V2.1






OB2268 Datasheet, Funktion
OB2268
OB2269
Current Mode PWM Controller
TD_OC
Over Current
Detection and
Control Delay
VTH_OC
Internal Current
Limiting Threshold
Voltage
Oscillator
FOSC
f_Temp
www.DataSheet4U.com
f_Volt
Normal Oscillation
Frequency
Frequency
Temperature
Stability
Frequency Voltage
Stability
RI_range
V_RI_open
F_BM
Operating RI Range
RI open load
voltage
Burst Mode Base
Frequency
Gate Drive Output
VOL
Output Low Level
VOH
Output High Level
VG_Clamp
Output Clamp
Voltage Level
T_r Output Rising Time
T_f Output Falling
Time
Over Temperature Protection
I_RT
Output Current of
RT pin
VTH_OTP
OTP Threshold
Voltage
VTH_OTP_off
OTP Recovery
Threshold Voltage
TD_OTP
OTP De-bounce
Time
V_RT_Open
RT Pin Open
Voltage
Frequency Shuffling (OB2269 Only)
f_OSC
Frequency
Modulation range
/Base frequency
f_Shuffling
Shuffling
Frequency
From Over Current Occurs
to GATE output turns off,
Sense voltage ramp at
0.15V/uS.
VDD = 16V, I(VIN) =
55uA
RI = 100 Kohm
VDD = 16V, RI =
100Kohm, 0oC to 85 oC
VDD = 15-25V, RI =
100Kohm
VDD = 16V, RI =
100Kohm
VDD = 16V, Io = 20 mA
VDD = 16V, Io = 20 mA
VDD = 16V, CL = 1nf
VDD = 16V, CL = 1nf
RI=100K
RI=100K
RI=100K
RI=100K
60
50
11
1.015
-5
120
0.86
65
5
5
100
2.0
22
18
120
50
70
1.065
1.165
100
3.5
65
70
250
0.3
1.115
5
nSec
V
KHZ
%
%
Kohm
V
KHZ
V
V
V
nSec
nSec
uA
V
V
uSec
V
%
HZ
©On-Bright Electronics
A Liteon Semiconductor Company
-6-
Confidential
V2.1

6 Page







OB2268 pdf, datenblatt
OB2268
OB2269
Current Mode PWM Controller
IMPORTANT NOTICE
RIGHT TO MAKE CHANGES
On-Bright Electronics Corp. reserves the right to make corrections, modifications, enhancements,
improvements, and other changes to its products and services at any time and to discontinue any product or
service without notice. Customers should obtain the latest relevant information before placing orders and should
verify that such information is current and complete.
WARRANTY INFORMATION
On-Bright Electronics Corp. warrants performance of its hardware products to the specifications applicable at
the time of sale in accordance with its standard warranty. Testing and other quality control techniques are used
www.DataSheteot4tUh.ceoemxtent it deems necessary to support this warranty. Except where mandated by government requirements,
testing of all parameters of each product is not necessarily performed.
On-Bright Electronics Corp. assumes no liability for applications assistance or customer product design.
Customers are responsible for their products and applications using On-Bright’s components, data sheet and
application notes. To minimize the risks associated with customer products and applications, customers should
provide adequate design and operating safeguards.
LIFE SUPPORT
On-Bright Electronics Corp.’s products are not designed to be used as components in devices intended to
support or sustain human life. On-bright Electronics Corp. will not be held liable for any damages or claims
resulting from the use of its products in medical applications.
MILITARY
On-Bright Electronics Corp.’s products are not designed for use in military applications. On-Bright Electronics
Corp. and Liteon Semiconductor Corp. will not be held liable for any damages or claims resulting from the use
of its products in military applications.
©On-Bright Electronics
A Liteon Semiconductor Company
- 12 -
Confidential
V2.1

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