OB2530Ax
High Precision CC/CV Primary-Side Power Switch
FEATURES
OB2530Ax is a high performance offline PSR
power switch for low power AC/DC charger and
adapter applications. It operates in primary-side
sensing
and
regulation.
Consequently,
opto-coupler and TL431 could be eliminated.
Proprietary Constant Voltage (CV) and Constant
Current (CC) control is integrated as shown in the
figure below.
In CC control, the current and output power setting
can be adjusted externally by the sense resistor
Rs at CS pin. In CV control, multi-mode operations
are utilized to achieve high performance and high
efficiency. In addition, good load regulation is
achieved by the built-in cable drop compensation.
Device operates in PFM in CC mode at large load
condition and it operates in PWM with frequency
reduction at light/medium load. The chip
consumes very low operation current. It achieves
less than 75mW standby power to meet strict
standby power standard.
OB2530Ax offers comprehensive protection
coverage with auto-recovery feature including
Cycle-by-Cycle current limiting, VDD over voltage
protection, feedback loop open protection, short
circuit protection, built-in leading edge blanking,
VDD under voltage lockout (UVLO), OTP etc.
OB2530Ax is offered in DIP8 packages.
Primary-side sensing and regulation without
TL431 and opto-coupler
High precision constant voltage and current
regulation at universal AC input
Multi-mode PWM/PFM operation for efficiency
improving
Integrated 2A 650V MOSFET
Good dynamic response
Programmable CV and CC regulation
Built-in primary winding inductance
compensation
Programmable cable drop compensation
No need for control loop compensation
Audio noise free operation
Built-in leading edge blanking (LEB)
Ultra low start-up current and low operating
current
Support capacitance loading
Comprehensive protection coverage with
auto-recovery
VDD over voltage protection
VDD under voltage lockout with
hysteresis (UVLO)
Cycle-by-Cycle current limiting
Feedback loop open protection
Output short circuit protection
On-chip OTP
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GENERAL DESCRIPTION
APPLICATIONS
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Low Power AC/DC offline SMPS for
Cell Phone Charger
Digital Cameras Charger
Small Power Adapter
Auxiliary Power for PC, TV etc.
Linear Regulator/RCC Replacement
Figure.1. Typical CC/CV Curve
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TYPICAL APPLICATION
©On-Bright Electronics
Confidential
-1-
Preliminary Datasheet
OB_DOC_DS_2530Ax02
OB2530Ax
High Precision CC/CV Primary-Side Power Switch
GENERAL INFORMATION
Absolute Maximum Ratings
Parameter
Drain Voltage (off state)
VDD Voltage
INV Input Voltage
CS Input Voltage
Min/Max Operating Junction
Temperature TJ
Operating
Ambient
Temperature TA
Min/Max
Storage
Temperature Tstg
Lead
Temperature
(Soldering, 10secs)
1
8
GND
NC
2
7
GND
6
3
DRAIN
o
INV
-40 to 150 ℃
-20 to 85 ℃
吉
VDD
Value
-0.3V to Bvdss
-0.3 to 28V
-0.3 to 7V
-0.3 to 7V
密
Pin Configuration
The pin map is shown as below for DIP8.
-55 to 150 ℃
260 ℃
Package Dissipation Rating
Package
RθJA (℃/W)
DIP8
75
Output Power Table
Part Number
90Vac~264Vac
OB2530APAP
12W
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DRAIN
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Ordering Information
Part Number
Description
OB2530APAP-H
DIP8, Haloger-free, Tube
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.
CS
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Recommended Operating Condition
Symbol
Parameter
Range
VDD
VDD Supply Voltage
8 to 25V
©On-Bright Electronics
Confidential
-2-
Preliminary Datasheet
OB_DOC_DS_2530Ax02
OB2530Ax
High Precision CC/CV Primary-Side Power Switch
TERMINAL ASSIGNMENTS
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Marking Information
Pin Num.
Pin Name
I/O
1
VDD
P
2
NC
3
INV
4
CS
I
Power MOSFET source
5/6
Drain
O
Drain of internal power MOSFET
GND
P
Ground
on
f
Power Supply
The voltage feedback from auxiliary winding. Connected to resistor
divider from auxiliary winding reflecting output voltage.
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7/8
Description
©On-Bright Electronics
Confidential
-3-
Preliminary Datasheet
OB_DOC_DS_2530Ax02
OB2530Ax
High Precision CC/CV Primary-Side Power Switch
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BLOCK DIAGRAM
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EA
©On-Bright Electronics
Confidential
-4-
Preliminary Datasheet
OB_DOC_DS_2530Ax02
OB2530Ax
High Precision CC/CV Primary-Side Power Switch
ELECTRICAL CHARACTERISTICS
I static
Test Conditions
Min
VDD=UVLO_OFF-1V
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485
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uA
1.0
mA
16.5
8.3
27.0
17.5
9.3
28.5
V
V
V
25
V
515
ns
mV
mV
300
500
590
2.475 2.500 2.525 V
2.0
445
490
us
Hz
KHz
40
45
50
uA
2.85
3.0
3.15
V
400
72
Rds,on(Ω)
On resistance
Min
Typ.
4.4
Max
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Unit
0.85
吉
15.5
7.3
26.0
Power MOSFET Section
BVdss(V)
Parameter
MOSFET Drain-Source Breakdown Voltage
Product
Min
Typ.
Max
OB2530APAP
650
Max
5
Static current
UVLO(OFF)
VDD under voltage lockout exit
UVLO(ON)
VDD under voltage lockout enter
VDD_OVP
VDD over voltage protection
Max. Operating
Voltage
Current Sense Input Section
TLEB
LEB time
Vth_ocp_min
Minimum over current threshold
Vth_ocp_max Maximum over current threshold
INV Input Section
Reference voltage for feedback
Vref_INV
threshold
Tpause_min
Minimum Toff
F_min
Minimum frequency
F_max
Maximum frequency
Maximum cable compensation
Icomp_cable
current
Output Over Voltage Protection
V_OVP
Output Over voltage threshold
Typ.
密
(TA = 25℃, VDD=15V, if not otherwise noted)
Symbol
Parameter
Supply Voltage (VDD) Section
I start-up
Start up current
©On-Bright Electronics
Confidential
-5-
Preliminary Datasheet
OB_DOC_DS_2530Ax02
OB2530Ax
High Precision CC/CV Primary-Side Power Switch
CHARACTERIZATION PLOTS
Ivdd_startup(uA) vs Tem perature
Ivdd(uA)
800
600
400
200
10.00
8.00
6.00
4.00
2.00
0.00
0
7
9
11
13
15
17
密
Ivdd_startup(uA)
1000
吉
Vdd(V) vs Ivdd(uA)
-40
19
-10
110 140
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19.00
18.20
17.40
16.60
15.80
15.00
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UVLO(OFF)(V)
9.00
8.80
8.60
8.40
8.20
8.00
-40
-10
20
50
80
110 140
-40
on
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Temperature(℃)
Vref(V) vs Tem perature
Vocp(V)
2.300
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Br
-40 -10
20
50
80
-10
20
50
80
110 140
Temperature(℃)
Vocp(V) vs Tem perature
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2.600
2.540
2.480
2.420
2.360
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Vref(V)
80
UVLO(OFF)(V) vs Tem perature
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UVLO(ON)(V)
UVLO(ON)(V) vs Tem perature
Icable(uA)
50
Temperature(℃)
VDD(V)
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20
0.600
0.560
0.520
0.480
0.440
0.400
-40
110 140
-10
20
50
80
110 140
Temperature(℃)
Temperature(℃)
Icable(uA) vs Tem perature
46.00
44.80
43.60
42.40
41.20
40.00
-40 -10
20
50
80
110 140
Temperature(℃)
©On-Bright Electronics
Confidential
-6-
Preliminary Datasheet
OB_DOC_DS_2530Ax02
OB2530Ax
High Precision CC/CV Primary-Side Power Switch
OPERATION DESCRIPTION
IS
OB2530Ax is a cost effective PSR power switch
optimized for off-line low power AC/DC
applications including battery chargers. It operates
in primary side sensing and regulation, thus
opto-coupler and TL431 are not required.
Proprietary built-in CV and CC control can achieve
high precision CC/CV control meeting most
charger application requirements.
NP
IP
NS
The auxiliary voltage reflects the output voltage as
shown in Figure.2 and it is given by
V AUX
N AUX
(VO V )
NS
(2)
密
Where V indicates the voltage drop of the
output Diode.
Startup Current and Start up Control
Startup current of OB2530Ax is designed to be
very low so that VDD could be charged up above
UVLO threshold level and device starts up quickly.
A large value startup resistor can therefore be
used to minimize the power loss yet achieve a
reliable startup in application.
VAUX
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Sampling Instance
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PWM Off
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Operating Current and Capacitance Loading
Startup
The operating current of OB2530Ax is as low as
850uA (typical). Good efficiency and les than
75mW standby power is achieved with the low
operating current. OB2530Ax increase the
minimum frequency up to 10KHz at startup to
support system capacitance loading startup, when
FB sampled voltage is higher than 1.55V or
system enter CV operation mode, the minimum
frequency resume the normal F_min(typical
445Hz).
TDemag
TON
PWM On
Figure.2. Auxiliary voltage waveform
on
f
Via a resistor divider connected between the
auxiliary winding and INV (pin 2), the auxiliary
voltage is sampled at the middle of the
de-magnetization and it is hold until the next
sampling. The sampled voltage is compared with
reference voltage Vref (typical 2.5V) and the
difference is amplified. The error amplifier output
reflects the load condition and controls the
switching off time to regulate the output voltage,
thus constant output voltage can be achieved.
When the sampled voltage is below Vref and the
error amplifier output reaches its minimum, the
switching frequency is controlled by the sampled
voltage to regulate the output current, thus the
constant output current can be achieved.
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CC/CV Operation
OB2530Ax is designed to produce good CC/CV
control characteristic as shown in the Figure. 1.
In charger applications, a discharged battery
charging starts in the CC portion of the curve until
it is nearly full charged and smoothly switches to
operate in CV portion of the curve. The CC portion
provides output current limiting. In CV operation,
the output voltage is regulated through the primary
side control. In CC operation mode, OB2530Ax will
regulate the output current constant regardless of
the output voltage drop.
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Adjustable CC Point and Output Power
In OB2530Ax series, the CC point and maximum
output power can be externally adjusted by
external current sense resistor Rs at CS pin as
illustrated in the typical application diagram. The
larger Rs, the smaller CC point is, and the smaller
output power becomes, and vice versa as shown
in Figure.3.
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Principle of Operation
To support OB2530Ax series proprietary CC/CV
control, system needs to be designed in DCM
mode for flyback system (Refer to Typical
Application Diagram in page1).
In the DCM flyback converter, the output voltage
can be sensed via the auxiliary winding. During
MOSFET turn-on time, the load current is supplied
from the output filter capacitor, Co, and the current
in the primary winding ramps up. When MOSFET
turns off, the energy stored in the primary winding
is transferred to the secondary side and the
current in the secondary winding is
©On-Bright Electronics
(1)
Confidential
-7-
Preliminary Datasheet
OB_DOC_DS_2530Ax02
OB2530Ax
密
High Precision CC/CV Primary-Side Power Switch
吉
Figure.3. Adjustable output power by changing Rs
Operation Switching Frequency
The switching frequency of OB2530Ax is
adaptively controlled according to the load
conditions and the operation modes.
For flyback operating in DCM, the maximum
output power is given by
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LP FSW I p2
2
Programmable Cable Drop Compensation
In OB2530Ax, cable drop compensation is
implemented to achieve good load regulation. An
offset voltage is generated at INV pin by an
internal current flowing into the resister divider.
The current is proportional to the switching off time,
as a result, it is inversely proportional to the output
load current, and the drop due to the cable loss
can be compensated. As the load current
decreases from full-load to no-load, the offset
voltage at INV will increase. It can also be
programmed by adjusting the resistance of the
divider to compensate the drop for various cable
lines used.
The percentage of maximum compensation is
Icomp _ cable ( R1 // R 2) 10 6
V
100%
2.5
Vout
V is load compensation voltage and Vout is
output voltage;
For example: R1//R2=6.2Kohm, the percentage of
maximum compensation is
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Figure.4. On time OCP compensation
(3)
1
2TDemag
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Where Lp indicate the inductance of primary
winding and Ip is the peak current of primary
winding.
Refer to the equation 3, the change of the primary
winding inductance results in the change of the
maximum output power and the constant output
current in CC mode. To compensate the change
from variations of primary winding inductance, the
switching frequency is locked by an internal loop
and the switching frequency is
(4)
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Since TDemag is inversely proportional to the
inductance, as a result, the product Lp and fsw is
constant, thus the maximum output power and
constant current in CC mode will not change as
primary winding inductance changes. Up to ±7%
variation of the primary winding inductance can be
compensated.
Br
V
45 6200 10 6
100% 11.16%
Vout
2.5
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On Time OCP Compensation
The variation of max output current in CC mode
can be rather large if no compensation is provided.
The OCP threshold value is self adjusted higher at
higher AC voltage. This OCP threshold slope
adjustment helps to compensate the increased
output current limit at higher AC voltage. In
OB2530Ax, a proprietary OCP compensation
block is integrated and no external components
are needed. The OCP threshold in OB2530Ax
series is a function of the switching ON time. For
the ON time between 1.6us to 6.4us (typical), the
OCP threshold changes linearly from 500mV to
590mV. For the ON time larger than 6.4us, the
OCP threshold is clamped to 590mV, as shown in
Figure 4.
©On-Bright Electronics
Current Sensing and Leading Edge Blanking
Cycle-by-Cycle current limiting is offered in
OB2530Ax. 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 power MOSFET on state so that the
external RC filtering on sense input is no longer
needed.
Confidential
-8-
Preliminary Datasheet
OB_DOC_DS_2530Ax02
OB2530Ax
High Precision CC/CV Primary-Side Power Switch
Gate Driver
The GATE pin is connected to the gate of an
external power switch. An internal 11V (typical)
clamp is added for MOSFET gate protection at
high VCC voltage. When VCC voltage drops below
UVLO(ON), the GATE pin is internally pull low to
maintain the off state.
with its rich protection features including precise
on-chip OTP, cycle-by-cycle current limiting (OCP),
output over voltage protection, VDD over voltage
protection, short circuit protection, under voltage
lockout on VDD (UVLO).
VDD is supplied by transformer auxiliary winding
output. The output of OB2530Ax is shut down
when VDD drops below UVLO (ON) and the power
converter enters power on start-up sequence
thereafter.
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Protection Control
Good power supply system reliability is achieved
©On-Bright Electronics
Confidential
-9-
Preliminary Datasheet
OB_DOC_DS_2530Ax02
OB2530Ax
High Precision CC/CV Primary-Side Power Switch
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PACKAGE MECHANICAL DATA
Symbol
O
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A
A1
A2
B
B1
C
D
E
E1
e
L
E2
Dimensions In Millimeters
Min
Max
3.710
5.334
0.381
2.921
4.953
0.350
0.650
1.524 (BSC)
0.200
0.360
9.000
10.160
6.096
7.112
7.320
8.255
2.540 (BSC)
2.921
3.810
7.620
10.920
©On-Bright Electronics
Confidential
- 10 -
Dimensions In Inches
Min
Max
0.146
0.210
0.015
0.115
0.195
0.014
0.026
0.06 (BSC)
0.008
0.014
0.354
0.400
0.240
0.280
0.288
0.325
0.1 (BSC)
0.115
0.150
0.300
0.430
Preliminary Datasheet
OB_DOC_DS_2530Ax02
OB2530Ax
High Precision CC/CV Primary-Side Power Switch
IMPORTANT NOTICE
密
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.
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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 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.
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.
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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.
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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.
©On-Bright Electronics
Confidential
- 11 -
Preliminary Datasheet
OB_DOC_DS_2530Ax02