OB2283

High Performance Current Mode PWM Controller

GENERAL DESCRIPTION FEATURES

OB2283 is a highly integrated current mode PWM ■ Power on soft start reducing MOSFET Vds
control IC optimized for high performance, low stress
standby power and cost effective offline flyback ■ Frequency shuffling for EMI
converter applications. ■ Extended burst mode control for improved
PWM switching frequency at normal operation is efficiency and low standby power design
internally fixed and is trimmed to tight range. At no ■ Audio noise free operation
load or light load condition, the IC operates in ■ Peak load operation with increased frequency
extended ‘burst mode’ to minimize switching loss. ■ Comprehensive protection coverage

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Lower standby power and higher conversion o VCC Under Voltage Lockout with
efficiency is thus achieved. hysteresis (UVLO)
VCC low startup current and low operating current o VCC Over Voltage Protection (VCC OVP)

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contribute to a reliable power on startup and low o Cycle-by-cycle over current threshold
standby design with OB2283. setting for constant output power limiting
OB2283 offers comprehensive protection over universal input voltage range
coverage with auto-recovery including Cycle-by- o Over Load Protection (OLP) with auto-
Cycle current limiting (OCP), over load protection recovery
(OLP), and VCC under voltage lockout (UVLO). It o External (if NTC resistor is connected at
also provides the protections with latched shut PRT pin)or internal Over Temperature
down including over temperature protection (OTP), Protection (OTP) with latched shut down
and over voltage protection (OVP). Excellent EMI o Output Over Voltage Protection(Output
performance is achieved with On-Bright OVP) with latched shut down, and the
proprietary frequency shuffling technique. OVP triggered voltage can be adjusted by
The tone energy at below 25KHz is minimized in the resistor connected between auxiliary
the design and audio noise is eliminated during winding and PRT pin
operation. o Output diode short protection with auto-
OB2283 is offered in SOT23-6 package. recovery
o GND open protection with auto-recovery
APPLICATIONS
Offline AC/DC flyback converter for
■ Printer, Storage power supply
■ Power Adapter

TYPICAL APPLICATION

EMI
AC IN
Filter DC
Out

Vaux

OB2283
6 FB VCC 1

5 PRT CS 2

4 GND GATE 3

©On-Bright Electronics Confidential Preliminary Datasheet

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High Performance Current Mode PWM Controller

Absolute Maximum Ratings

GENERAL INFORMATION
Parameter Value
Pin Configuration
VCC DC Supply Voltage VOVP-1V
FB Input Voltage -0.3 to 7V
VCC 1 6 FB CS Input Voltage -0.3 to 7V
PRT Input Voltage -0.3 to 7V
CS 2 5 PRT
Min/Max Operating
-40 to 150 ℃
Junction Temperature TJ

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Gate 3 4 GND
Min/Max Storage
-55 to 150 ℃
Temperature Tstg

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Ordering Information Lead Temperature
260 ℃
Part Number Description (Soldering, 10secs)
OB2283MP SOT23-6, Pb-free in T&R 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
Package Dissipation Rating at these or any other conditions beyond those indicated under
Package RJA(℃/W) “recommended operating conditions” is not implied. Exposure
SOT23-6 200 to absolute maximum-rated conditions for extended periods
may affect device reliability.

Recommended operating condition

Symbol Parameter Range
VCC VCC Supply Voltage 12 to 28V
Operating Ambient
TA -20 to 85 ℃
Temperature

OB2283 X X

High Performance Current Mode PWM

Package Package Pb-free
Controller

M:SOT23-6 P:Pb-free

Marking Information

83YWW S
. ZZZ

Y:Year Code
WW:Week Code(01-52)
s: Internal code
ZZZ: Lot code

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High Performance Current Mode PWM Controller

TERMINAL ASSIGNMENTS
Pin Name I/O Description
VCC P Power Supply
CS I Current sense input
Gate O Totem-pole gate driver output for power MOSFET
GND P Ground

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Dual functions pin. Connecting a NTC resistor to ground for OTP detection.
Connecting a resistor from Vaux can adjust OVP trigger voltage. If both OTP and
PRT I
OVP are needed, a diode should be connected between PRT pin and the NTC

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resistor.
Feedback input pin. The PWM duty cycle is determined by voltage level into this pin
FB I
and the current-sense signal at Pin CS.

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High Performance Current Mode PWM Controller

FUNCTIONAL BLOCK DIAGRAM

Logic
S Q Soft Driver
Control

R
OVP
OVP

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AVDD Diode
UVLO short
Diode

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short
Internal
blocks OSC Slope LEB
Vref& OCP compensation
Iref Comparator Vocp

Diode
short OLP
AVDD
GND
open PWM
PK/Green/ Comparator
Burst
Temp
sense Timer OLP

OTP
EX OTP OVP
Latch

EX OVP

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ELECTRICAL CHARACTERISTICS
(TA = 25℃, VCC=18V, unless otherwise noted)
Symbol Parameter Test Conditions Min Typ Max Unit
Supply Voltage (VDD)
VCC=UVLO(OFF)-1V,
Istartup VCC Start up Current measure leakage 3 10 uA
current into VCC
VDD=18V,CS=4V,
I_VCC_Operation Operation Current FB=3.5V,measure 2.5 3 mA

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I(VCC)
CS=0V,FB=0.5V,
I_VCC_Burst Burst Current 0.55 0.65 mA
measure I(VCC)

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VCC Under Voltage Lockout
UVLO(ON) 7 8 9 V
Enter
VCC Under Voltage Lockout
UVLO(OFF) 19 21 23 V
Exit (Recovery)
Vpull-up Pull-up PMOS active 10 V
FB=3V,CS=0V. Slowly
VCC Over Voltage Protection
OVP ramp VCC, until no 29 30 31 V
threshold voltage
gate switching.
Vlatch_release Latch release voltage 5 V
Feedback Input Section(FB Pin)
VFB_Open VFB Open Loop Voltage 5.1 V
Avcs PWM input gain ∆VFB/∆VCS 3.5 V/V
Maximum duty Max duty cycle @
75 78 81 %
cycle VCC=18V,VFB=3V,VCS=0V
Vref_green The threshold enter green mode 1.85 V
Vref_burst_H The threshold exits burst mode 1.33 V
The threshold enters burst
Vref_burst_L 1.23 V
mode
Short FB pin to GND
IFB_Short FB pin short circuit current 0.3 mA
and measure current
Open loop protection, FB
VTH_OLP 4.4 V
Threshold Voltage
Open loop protection,
Td_OLP 15 ms
Debounce Time
ZFB_IN Input Impedance 16 Kohm
Current Sense Input(CS Pin)
SST_CS Soft start time for CS peak 4 ms
T_blanking Leading edge blanking time 250 ns
From Over Current
Over Current Detection and Occurs till the Gate
Td_OC 90 ns
Control Delay driver output start to
turn off
Internal Current Limiting
VTH_OC Threshold Voltage with zero 0.43 0.45 0.47 V
duty cycle
VTH_OC_Clamp OCP CS voltage clamper 0.69 V
Vdiode_scp Diode short protection voltage 1.4 V
Td_dio Diode short debounce time 8 Cycles

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High Performance Current Mode PWM Controller

GND open protection voltage

Vgnd_open difference between GND and 0.3 V
CS
GND open protection
Td_gnd_open 20 us
debounce time
Over Current protection
Td_OCP 60 ms
debounce Time
PRT pin
Output current for external OTP
IRT 95 100 105 uA
detection

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Threshold voltage for external
VOTP 0.95 1 1.05 V
OTP

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Td_OTP External OTP debounce time 5 Cycles
Current threshold for adjustable
Ioutput_ovp 70 uA
output OVP
Td_output_ovp Output OVP debounce time 5 Cycles
In-chip OTP
OTP enter 150 ℃
OTP exit 120 ℃
Oscillator
VDD=18V,FB=3V,
FOSC Normal Oscillation Frequency 60 65 70 KHz
CS=0V
VDD=18V,FB=4.5V,
Fosc_PK Peak frequency 142 KHz
CS=0V
SST_freq Soft start time of frequency 30 ms
△f_OSC Frequency jittering +/-6 %
F_shuffling Shuffling frequency 32 Hz
Frequency Temperature
△f_Temp 1 %
Stability
△f_VCC Frequency Voltage Stability 1 %
F_Burst Burst Mode Switch Frequency 25 KHz
Gate driver
Output low level @ VDD=18V,
VOL 1 V
Io=5mA
Output high level @ VCC=18V,
VOH 6 V
Io=20mA
V_clamping Output clamp voltage 12 V
Output rising time 1.2V ~ 10.8V
T_r 160 ns
@ CL=1000pF
Output falling time 10.8V ~ 1.2V
T_f 50 ns
@ CL=1000pF

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High Performance Current Mode PWM Controller

CHARACTERIZATION PLOTS
VDD = 18V, TA = 25℃ condition applies if not otherwise noted.

UVLO_ON vs Temperature UVLO_OFF vs Temperature

8 21

7.8 20.8

UVLO_OFF(V)
UVLO_ON(V)

7.6 20.6

7.4 20.4

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7.2 20.2

7 20

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-40 -10 20 50 80 110 140 -40 -10 20 50 80 110 140
Tem perature(℃) Tem perature(℃)

Fosc vs Tem perature Ton_com p vs Tem perature

70 8

68 7.8
Ton_comp (us)
Fosc(KHz)

66 7.6

64 7.4

62 7.2

60 7
-40 -10 20 50 80 110 140 -40 -10 20 50 80 110 140

Temperature( ℃) Temperature( ℃)

VOTP vs Tem perature V TH_OC vs Tem perature

1.05 0.6

1.03 0.54
VTH _OC(V)
VOTP(V)

1.01 0.48

0.99 0.42

0.97 0.36

0.95 0.3
-40 -10 20 50 80 110 140 -40 -10 20 50 80 110 140
Temperature( ℃) Temperature( ℃)

OVP vs Tem perature IRT vs Tem perature

120
30

29.6 110
IRT (V)

29.2
OVP (V)

100
28.8

28.4 90

28 80
-40 -10 20 50 80 110 140 -40 -10 20 50 80 110 140
Temperature( ℃) Temperature( ℃)

©On-Bright Electronics Confidential Preliminary Datasheet

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High Performance Current Mode PWM Controller

OPERATION DESCRIPTION
OB2283 is a highly integrated current mode PWM snubber circuit. The magnitude of power loss is in
control IC optimized for high performance, low proportion to the switching frequency. Lower
standby power and cost effective offline flyback switching frequency leads to the reduction on the
converter applications. The ‘extended burst mode’ power loss and thus conserves the energy.
control greatly reduces the standby power The switching frequency is internally adjusted at
consumption and helps the design easier to meet no load or light load condition. The switch
the international power conservation requirements. frequency reduces at light/no load condition to
improve the conversion efficiency. At light load or
 Startup Current and Start up Control no load condition, the FB input drops below

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Startup current of OB2283 is designed to be very Vref_burst_L (the threshold enter burst mode) and
low so that VCC could be charged up above device enters Burst Mode control. The Gate drive
UVLO threshold level and device starts up quickly. output switches when FB input rises back to

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A large value startup resistor can therefore be Vref_burst_H (the threshold exit burst mode).
used to minimize the power loss yet achieve a Otherwise the gate drive remains at off state to
reliable startup in application. minimize the switching loss and reduces the
standby power consumption to the greatest
 Operating Current extend.
The Operating current of OB2283 is low at 2.5mA
(typical). Good efficiency is achieved with OB2283  Oscillator Operation
low operation current together with the ‘extended During the full load power operation, OB2283
burst mode’ control features. operates at a 65KHz (typical) fixed frequency. The
efficiency and system cost is controlled at an
 Soft Start optimal level. A peak power mode is implemented
OB2283 features an internal 4ms (typical) soft to supply a peak current output requirement. In
start to soften the electrical stress occurring in the peak power mode, frequency is increased from
power supply during startup. It is activated during 65KHz (typical) to 142KHz (typical).
the power on sequence. As soon as VCC reaches At light load levels, OB2283 enters the light load
UVLO(OFF), the CS peak voltage is gradually mode, where the output current is reduced. The
increased from 0.05V to the maximum level. switching losses are reduced by lowering the
Every restart up is followed by a soft start. switching frequency.

 Frequency shuffling for EMI improvement

The frequency shuffling (switching frequency
modulation) is implemented in OB2283. The
oscillation frequency is modulated so that the tone
energy is spread out. The spread spectrum
minimizes the conduction band EMI and therefore
eases the system design.

 Current Sensing and Leading Edge

Blanking
Cycle-by-Cycle current limiting is offered in
OB2283 current mode PWM control. The switch
current is detected by a sense resistor into the CS
pin. An internal leading edge blanking circuit
chops off the sensed voltage spike at initial
internal power MOSFET on state due to snubber
 Extended Burst Mode Operation diode reverse recovery and surge gate current of
At light load or no load condition, most of the power MOSFET. The current limiting comparator
power dissipation in a switching mode power is disabled and cannot turn off the internal power
supply is from switching loss of the MOSFET, the MOSFET during the blanking period. The PWM
core loss of the transformer and the loss of the

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High Performance Current Mode PWM Controller

duty cycle is determined by the current sense realized through time-division technology as
input voltage and the FB input voltage. shown in the figure.
For external OTP detecttion, when switch control
 Internal Synchronized Slope Compensation signal S1= “1”, about 20uA (typical) current flows
Built-in slope compensation circuit adds voltage out from PRT pin. When switch control signal S0=
ramp into the current sense input voltage for PWM “1”,about 120uA (typical) current flows out from
generation. This greatly improves the close loop PRT pin. The PRT pin voltage difference △Votp
stability at CCM and prevents the sub-harmonic at phase S0 and S1 phase is equal to RT*Iotp.
oscillation and thus reduces the output ripple When △Votp<1V , external OTP latch protection
voltage. is triggered after 5 Gate cycles debounce.

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 Driver For output OVP detection, when Sovp= “1”, Iovp is
The power MOSFET is driven by a dedicated gate equal to Vo/ROVP. If Iovp is larger than 70uA
driver for power switch control. Too weak the gate

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(typical), OVP latch protection is triggered after 5
driver strength results in higher conduction and Gate cycles debounce. By selecting proper Rovp
switch loss of MOSFET while too strong gate resistance, output OVP level can be programmed.
driver strength results the compromise of EMI.
A good tradeoff is achieved through the built-in  Protection Controls
totem pole gate design with right output strength Good power supply system reliability is achieved
and dead time control. The low idle loss and good with auto-recovery protection features including
EMI system design is easier to achieve with this Cycle-by-Cycle current limiting (OCP), and Under
dedicated control scheme. Voltage Lockout on VDD (UVLO), and latched
shutdown features including Over Temperature
 Dual Function of External OTP and Output Protection (OTP), VCC and output Over Voltage
OVP Protection (OVP).
With On-Bright proprietary technology, the OCP is
line voltage compensated to achieve constant
output power limit over the universal input voltage
range.

At overload condition when FB input voltage

exceeds power limit threshold value for more than
Td_OLP, control circuit reacts to shut down the
converter. It restarts when VDD voltage drops
below UVLO limit. For protection with latched shut
down mode, control circuit shuts down (latch) the
power MOSFET when an over temperature
condition or over voltage condition is detected
until VDD drops below 5V (typical) (Latch release
voltage), and the device enters power on restart-
up sequence thereafter.

At output diode short condition, CS can ramp

higher than 1.4V (typical). After 8 cycles debounce
time for CS higher than 1.4V (typical), auto-
recover protection is triggered.

At GND open condition, the voltage of GND is

higher than CS. If GND is greater than CS+0.3V
(typical) for more than 20us (typical), auto-recover
protection is triggered.

On-Bright proprietary dual function of external  Pin Floating and Short Protection
OTP and output OVP provides feasible and OB2283 provides PIN floating protection for all the
accurate detection of external OTP through NTC pins and pin short protection for adjacent pins. In
resistor and output OVP. The dual function is the cases when a pin is floating or two adjacent
pins are shorted, Gate switching is disabled.

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High Performance Current Mode PWM Controller

PACKAGE MECHANICAL DATA

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Dimensions In Millimeters Dimensions In Inches
Symbol
Min Max Min Max
A 1.000 1.450 0.039 0.057
A1 0.000 0.150 0.000 0.006
A2 0.900 1.300 0.035 0.051
b 0.300 0.500 0.012 0.020
c 0.080 0.220 0.003 0.009
D 2.800 3.020 0.110 0.119
E 1.500 1.726 0.059 0.068
E1 2.600 3.000 0.102 0.118
e 0.950 (BSC) 0.037 (BSC)
e1 1.800 2.000 0.071 0.079
L 0.300 0.600 0.012 0.024
θ 0º 8º 0º 8º

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High Performance 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

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techniques are used to the extent it deems necessary to support this warranty. Except where mandated
by government requirements, testing of all parameters of each product is not necessarily performed.

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On-Bright Electronics Corp. assumes no liability for application 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. will not be held liable for any damages or claims resulting from the use of its products in
military applications.

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