High Performance Current Mode PWM Controller
OB2273A
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.
FEATURES
■
■
■
■
■
■
■
id
nf
OB2273A is offered in SOT23-6 package.
TYPICAL APPLICATION
O
n-
©On-Bright Electronics
Br
ig
ht
co
en
Confidential
-1-
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
tia
APPLICATIONS
Offline AC/DC flyback converter for
■
Battery Charger
■
Power Adaptor
■
Set-Top Box Power Supplies
■
Open-frame SMPS
lt
o
英
诺
Datasheet
OB_DOC_DS_2273AA2
尔
High Performance Current Mode PWM Controller
OB2273A
GENERAL INFORMATION
Pin Configuration
The OB2273A is offered in SOT23-6 package,
shown as below.
Package Dissipation Rating
Package
RJA(℃/W)
SOT23-6
200
nf
id
OB2273A
en
X
Ordering Information
Part Number
Description
OB2273AMP
SOT23-6, Pb-free in T&R
ig
ht
Current Mode PWM Controller with
Frequency shuffling
co
n-
Br
Marking Information
O
73YWW
S
. ZZZA
Y:Year Code
WW:Week Code(01-52)
s: Internal code
ZZZ: Lot code
A: Character code
©On-Bright Electronics
Confidential
-2-
tia
Package
M:SOT23-6
Absolute Maximum Ratings
Parameter
Value
VDD DC Supply Voltage
VOVP-1V
VDD Zener Clamp
VDD_Clamp+0.1V
Voltage
Note
VDD DC Clamp Current
10 mA
FB Input Voltage
-0.3 to 7V
Sense Input Voltage
-0.3 to 7V
RT Input Voltage
-0.3 to 7V
Min/Max Operating
-40 to 150
℃
Junction Temperature TJ
Min/Max Storage
-55 to 150
℃
Temperature Tstg
Lead
Temperature
260
℃
(Soldering, 10secs)
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.
lt
X
o
P:Pb-free
Package Pb-free
英
诺
Datasheet
OB_DOC_DS_2273AA2
尔
High Performance Current Mode PWM Controller
OB2273A
TERMINAL ASSIGNMENTS
Pin Name
GND
FB
RT
CS
VDD
Gate
I/O
P
I
I
I
P
O
Description
Ground
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
temperature shutdown/latch control or connected through Zener to VDD for
adjustable over voltage protection
Current sense input
Power Supply
Totem-pole gate driver output for power Mosfet
O
n-
©On-Bright Electronics
Br
ig
ht
co
nf
id
en
BLOCK DIAGRAM
Confidential
-3-
tia
Symbol
VDD
T
A
Parameter
VDD Supply Voltage
Operating Ambient Temperature
Min/Max
12 to 25
-20 to 85
o
C: Optional Internal Code
RECOMMENDED OPERATING CONDITION
lt
英
诺
Datasheet
OB_DOC_DS_2273AA2
尔
Unit
V
℃
High Performance Current Mode PWM Controller
OB2273A
ELECTRICAL CHARACTERISTICS
(T
A
= 25℃, VDD=18V, unless otherwise noted)
Symbol
Parameter
Supply Voltage (VDD)
Istartup
I_VDD_Operation
UVLO(ON)
UVLO(OFF)
Vpull-up
Vdd_clamp
OVP(ON)
VDD Start up Current
Operation Current
VDD Under Voltage Lockout
Enter
VDD Under Voltage Lockout
Exit (Recovery)
Pull-up PMOS active
Over
voltage
voltage
protection
Test Conditions
VDD=UVLO(OFF)-
1V, measure
leakage current
into VDD
V
FB
=3V
8
Min
Typ
Max
Unit
5
1.8
9
20
2.5
10
16.3
34
30
uA
mA
V
V
V
V
V
V
V/V
nf
Feedback Input Section(FB Pin)
V
FB_
Open
V
FB
Open Loop Voltage
Avcs
PWM input gain
ΔVFB/ΔVCS
Maximum
duty Max
duty
cycle
@
cycle
VDD=14V,VFB=3V,VCS=0V
The threshold enter green
Vref_green
mode
Vref_burst_H
The threshold exit burst mode
The threshold enter burst
Vref_burst_L
mode
lt
Ivdd=10mA
CS=0V,FB=3V
Ramp up VDD until
gate clock is off
o
tia
英
诺
14.3
15.3
30
13
32
26
28
4.2
2
80
2
1.275
1.175
3.9
75
0.4
3.7
80
88
16
4
220
40
120
0.725
0.75
0.9
60
65
+/-4
32
1
尔
85
96
0.775
70
en
%
V
V
V
mA
V
mSec
Kohm
ms
ns
Kohm
nSec
id
Br
Power Limiting FB Threshold
Voltage
T
D
_PL
Power limiting Debounce Time
Z
FB
_IN
Input Impedance
Current Sense Input(CS Pin)
SST
Soft start time
T_blanking
Leading edge blanking time
Z
SENSE
_IN
Input Impedance
V
TH
_PL
ig
ht
co
I
FB
_Short
FB pin short circuit current
Short FB pin to
GND and measure
current
O
n-
T
D
_OC
Over Current Detection and
Control Delay
Internal
Current
Limiting
Threshold Voltage with zero
duty cycle
CS voltage clamper
Normal Oscillation Frequency
Frequency jittering
Shuffling frequency
Frequency
Temperature
Stability
From Over Current
Occurs
till
the
Gatedrive
output
start to turn off
V
TH
_OC
Vocp_clamping
Oscillator
F
OSC
△f_OSC
F_shuffling
△f_Temp
V
V
KHZ
%
Hz
%
VDD=14V, FB=3V,
CS=0V
©On-Bright Electronics
Confidential
-4-
Datasheet
OB_DOC_DS_2273AA2
High Performance Current Mode PWM Controller
OB2273A
△f_VDD
F_Burst
Gate driver
VOL
Frequency Voltage Stability
Burst Mode Switch Frequency
1
22
1
6
175
85
%
KHZ
V
V
O
n-
©On-Bright Electronics
Br
ig
ht
co
nf
id
en
Confidential
-5-
tia
lt
Ouput low level @ VDD=14V,
Io=5mA
Ouput high level @ VDD=14V,
VOH
Io=20mA
V_clamping
Output clamp voltage
Output rising time 1V ~ 12V @
T_r
CL=1000pF
Output falling time 12V ~ 1V
T_f
@ CL=1000pF
Over temperature protection
IRT
Output current of RT pin
VOTP
Threshold voltage for OTP
Td_OTP
OTP debounce time
VRT_FL
Float voltage at RT pin
External
OVP
threshold
Vth_OVP
voltage
尔
105
1.05
12
V
nS
nS
uA
V
Cycle
V
V
o
英
诺
95
0.95
100
1
6
2.3
4
Datasheet
OB_DOC_DS_2273AA2
FPGA/CPLD
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
