OB2273A Datasheet PDF - On-Bright

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OB2273A
On-Bright

Part Number OB2273A
Description High Performance Current Mode PWM Controller
Page 10 Pages


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OB2273A
High Performance Current Mode PWM Controller
GENERAL DESCRIPTION
OB2273A is a highly integrated current mode
PWM control IC optimized for high performance,
low standby power and cost effective offline
flyback converter applications.
PWM switching frequency at normal operation is
internally fixed and is 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.
VDD low startup current and low operating current
contribute to a reliable power on startup and low
standby design with OB2273A.
OB2273A offers complete protection coverage
with auto-recovery including Cycle-by-Cycle
current limiting (OCP), over load protection (OLP),
VDD under voltage lockout (UVLO), over
temperature protection (OTP), and over voltage
(fixed or adjustable) protection (OVP). Excellent
EMI performance is achieved with On-Bright
proprietary frequency shuffling technique.
The tone energy at below 20KHZ is minimized in
the design and audio noise is eliminated during
operation.
OB2273A is offered in SOT23-6 package.
FEATURES
Level 5 compliance with <100mW standby
power at universal AC input.
Power on Soft Start Reducing MOSFET Vds
Stress
Frequency shuffling for EMI
Extended Burst Mode Control For Improved
Efficiency and Minimum Standby Power
Design
Audio Noise Free Operation
Fixed 65KHZ Switching Frequency
Comprehensive Protection Coverage
o VDD Under Voltage Lockout with
Hysteresis (UVLO)
o Cycle-by-cycle over current threshold
setting for constant output power limiting
over universal input voltage range
o Overload Protection (OLP) with auto-
recovery
o Over Temperature Protection (OTP) with
auto-recovery
o VDD Over voltage Protection(OVP) with
auto-recovery
o Adjustable OVP through external Zener
APPLICATIONS
Offline AC/DC flyback converter for
Battery Charger
Power Adaptor
Set-Top Box Power Supplies
Open-frame SMPS
TYPICAL APPLICATION
©On-Bright Electronics
Confidential
-1-
Datasheet
OB_DOC_DS_2273AA2



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OB2273A
High Performance Current Mode PWM Controller
GENERAL INFORMATION
Pin Configuration
The OB2273A is offered in SOT23-6 package,
shown as below.
Ordering Information
Part Number
OB2273AMP
Description
SOT23-6, Pb-free in T&R
Package Dissipation Rating
Package
RJA(/W)
SOT23-6
200
Absolute Maximum Ratings
Parameter
VDD DC Supply Voltage
VDD Zener Clamp
VoltageNote
VDD DC Clamp Current
FB Input Voltage
Sense Input Voltage
RT Input Voltage
Min/Max Operating
Junction Temperature TJ
Min/Max Storage
Temperature Tstg
Lead
Temperature
(Soldering, 10secs)
Value
VOVP-1V
VDD_Clamp+0.1V
10 mA
-0.3 to 7V
-0.3 to 7V
-0.3 to 7V
-40 to 150
-55 to 150
260
Note: VDD_Clamp has a typical value of 32V
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.
OB2273A X
X
Current Mode PWM Controller with
Frequency shuffling
Marking Information
Package
M:SOT23-6
Package Pb-free
P:Pb-free
73YWW S
. ZZZA
©On-Bright Electronics
Y:Year Code
WW:Week Code(01-52)
s: Internal code
ZZZ: Lot code
A: Character code
Confidential
-2-
Datasheet
OB_DOC_DS_2273AA2



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OB2273A
High Performance Current Mode PWM Controller
TERMINAL ASSIGNMENTS
Pin Name
GND
FB
RT
CS
VDD
Gate
I/O Description
P Ground
I
Feedback input pin. The PWM duty cycle is determined by voltage level into this pin
and the current-sense signal at Pin 4.
Dual function pin. Either connected through a NTC resistor to ground for over
I temperature shutdown/latch control or connected through Zener to VDD for
adjustable over voltage protection
I Current sense input
P Power Supply
O Totem-pole gate driver output for power Mosfet
RECOCM:MOpEtiNonDalEInDteOrnaPl ECRodAeTING CONDITION
Symbol
VDD
TA
Parameter
VDD Supply Voltage
Operating Ambient Temperature
Min/Max
12 to 25
-20 to 85
Unit
V
BLOCK DIAGRAM
©On-Bright Electronics
Confidential
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Datasheet
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OB2273A
High Performance Current Mode PWM Controller
ELECTRICAL CHARACTERISTICS
(TA = 25, VDD=18V, unless otherwise noted)
Symbol
Parameter
Supply Voltage (VDD)
Istartup
VDD Start up Current
I_VDD_Operation
UVLO(ON)
UVLO(OFF)
Vpull-up
Vdd_clamp
Operation Current
VDD Under Voltage Lockout
Enter
VDD Under Voltage Lockout
Exit (Recovery)
Pull-up PMOS active
OVP(ON)
Over voltage protection
voltage
Feedback Input Section(FB Pin)
VFB_Open
VFB Open Loop Voltage
Avcs
PWM input gain ΔVFB/ΔVCS
Maximum duty Max duty cycle @
cycle
VDD=14V,VFB=3V,VCS=0V
Vref_green
The threshold enter green
mode
Vref_burst_H
The threshold exit burst mode
Vref_burst_L
The threshold enter burst
mode
IFB_Short
FB pin short circuit current
VTH_PL
Power Limiting FB Threshold
Voltage
TD_PL
Power limiting Debounce Time
ZFB_IN
Input Impedance
Current Sense Input(CS Pin)
SST Soft start time
T_blanking
Leading edge blanking time
ZSENSE_IN
Input Impedance
TD_OC
Over Current Detection and
Control Delay
VTH_OC
Vocp_clamping
Oscillator
FOSC
f_OSC
F_shuffling
f_Temp
Internal Current Limiting
Threshold Voltage with zero
duty cycle
CS voltage clamper
Normal Oscillation Frequency
Frequency jittering
Shuffling frequency
Frequency
Temperature
Stability
Test Conditions
VDD=UVLO(OFF)-
1V, measure
leakage current
into VDD
VFB=3V
Ivdd=10mA
CS=0V,FB=3V
Ramp up VDD until
gate clock is off
Short FB pin to
GND and measure
current
From Over Current
Occurs till the
Gatedrive output
start to turn off
VDD=14V, FB=3V,
CS=0V
Min
8
14.3
30
26
3.9
75
80
0.725
60
Typ
5
1.8
9
15.3
13
32
28
4.2
2
80
2
1.275
1.175
0.4
3.7
88
16
4
220
40
120
0.75
0.9
65
+/-4
32
1
Max
20
2.5
10
16.3
34
30
85
96
0.775
70
Unit
uA
mA
V
V
V
V
V
V
V/V
%
V
V
V
mA
V
mSec
Kohm
ms
ns
Kohm
nSec
V
V
KHZ
%
Hz
%
©On-Bright Electronics
Confidential
-4-
Datasheet
OB_DOC_DS_2273AA2



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