OBGZ33
High Precision CC/CV Primary-Side Power Switch
FEATURES
OBGZ33 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.
OBGZ33
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.
OBGZ33 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
Meet CoC Tier 2 & DOE Level 6
Integrated 2A 620V 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
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
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APPLICATIONS
C
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
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Figure.1. Typical CC/CV Curve
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TYPICAL APPLICATION
©On-Bright Electronics
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Preliminary Datasheet
OB_DOC_DS_GZ3300
OBGZ33
High Precision CC/CV Primary-Side Power Switch
GENERAL INFORMATION
Pin Configuration
The pin map is shown as below for DIP8.
1
8
GND
NC
2
7
GND
6
CS
DRAIN
5
4
DRAIN
-20 to 85 ℃
-55 to 150 ℃
260 ℃
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.
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Ordering Information
Part Number
Description
OBGZ33AP
DIP8, Pb-free, Tube
Output Power Table
Part Number
90Vac~264Vac
OBGZ33AP
12W
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Package Dissipation Rating
Package
RθJA (℃/W)
DIP8
75
-40 to 150 ℃
佳
3
o
INV
Value
-0.3V to Bvdss
-0.3 to 28V
-0.3 to 7V
-0.3 to 7V
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VDD
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)
on
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Recommended Operating Condition
Symbol
Parameter
Range
VDD
VDD Supply Voltage
8 to 25V
X
X
C
OBGZ33
Package
A:DIP8
Green Package
P:Green
(Halogen-free)
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High Precision CC/CV Primary-Side PWM
Power Switch
©On-Bright Electronics
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Preliminary Datasheet
OB_DOC_DS_GZ3300
OBGZ33
High Precision CC/CV Primary-Side Power Switch
Marking Information
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YWWZZZ
OBGZ33AP
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Y:Year Code
WW:Week Code(01-52)
ZZZ:Lot Code
A:DIP8 Package
P:Green Package(Halogen-free)
s:Internal Code(Optional)
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TERMINAL ASSIGNMENTS
Pin Name
I/O
Description
1
VDD
P
Power Supply
2
NC
3
INV
I
The voltage feedback from auxiliary winding. Connected to resistor
divider from auxiliary winding reflecting output voltage.
4
CS
I
Power MOSFET source
5/6
Drain
7/8
GND
C
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Pin Num.
Drain of internal power MOSFET
P
Ground
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O
©On-Bright Electronics
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Preliminary Datasheet
OB_DOC_DS_GZ3300
OBGZ33
High Precision CC/CV Primary-Side Power Switch
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BLOCK DIAGRAM
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EA
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Preliminary Datasheet
OB_DOC_DS_GZ3300
OBGZ33
High Precision CC/CV Primary-Side Power Switch
ELECTRICAL CHARACTERISTICS
(TA = 25℃, VDD=15V, if not otherwise noted)
Symbol
Parameter
Supply Voltage (VDD) Section
I start-up
Start up current
I static
Test Conditions
Min
Typ.
VDD=UVLO_OFF-1V
5
1.0
mA
16.5
8.3
27.0
17.5
9.3
28.5
V
V
V
25
V
515
ns
mV
mV
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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
620
C
uA
0.85
佳
15.5
7.3
26.0
485
Unit
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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
MOSFET Section
Mosfet Drain-Source Breakdown
BVdss
Voltage
Static drain to source on
Rdson
resistance
Max
V
Ώ
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4.4
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Preliminary Datasheet
OB_DOC_DS_GZ3300
OBGZ33
High Precision CC/CV Primary-Side Power Switch
CHARACTERIZATION PLOTS
Ivdd_startup(uA) vs Tem perature
Vdd(V) vs Ivdd(uA)
Ivdd(uA)
800
600
400
200
0
7
9
11
13
15
17
10.00
8.00
6.00
4.00
2.00
0.00
-40
19
-10
50
80
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Temperature(℃)
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-40
20
50
80
50
80
110 140
0.600
0.560
0.520
0.480
0.440
0.400
-40
110 140
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-40 -10
20
Vocp(V) vs Tem perature
Vocp(V)
on
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Vref(V)
2.300
-10
Temperature(℃)
Vref(V) vs Tem perature
2.600
2.540
2.480
2.420
2.360
110 140
佳
110 140
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
20
80
UVLO(OFF)(V) vs Tem perature
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UVLO(ON)(V)
UVLO(ON)(V) vs Tem perature
-10
50
Temperature(℃)
VDD(V)
-40
20
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Ivdd_startup(uA)
1000
-10
20
50
80
110 140
Temperature(℃)
Br
Temperature(℃)
Icable(uA)
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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(℃)
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Preliminary Datasheet
OB_DOC_DS_GZ3300
OBGZ33
High Precision CC/CV Primary-Side Power Switch
output Diode.
OPERATION DESCRIPTION
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OBGZ33 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.
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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
OBGZ33 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, OBGZ33 will
regulate the output current constant regardless of
the output voltage drop.
Figure.2. Auxiliary voltage waveform
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Operating Current
The operating current of OBGZ33 is as low as
850uA (typical). Good efficiency and les than
75mW standby power is achieved with the low
operating current.
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Startup Current and Start up Control
Startup current of OBGZ33 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.
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Adjustable CC Point and Output Power
In OBGZ33 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 OBGZ33 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
IS
NP
IP
NS
(1)
Figure.3. Adjustable output power by changing Rs
The auxiliary voltage reflects the output voltage as
shown in Figure.2 and it is given by
V AUX
N AUX
(VO V )
NS
Operation Switching Frequency
The switching frequency of OBGZ33 is adaptively
controlled according to the load conditions and the
operation modes.
For flyback operating in DCM, the maximum
output power is given by
(2)
Where V indicates the voltage drop of the
©On-Bright Electronics
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-7-
Preliminary Datasheet
OB_DOC_DS_GZ3300
OBGZ33
High Precision CC/CV Primary-Side Power Switch
Po MAX
1
LP FSW I p2
2
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
(3)
1
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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
OBGZ33, a proprietary OCP compensation block
is integrated and no external components are
needed. The OCP threshold in OBGZ33 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.
45 6200 10 6
V
100% 11.16%
2.5
Vout
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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.
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(4)
2TDemag
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FSW
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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
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Current Sensing and Leading Edge Blanking
Cycle-by-Cycle current limiting is offered in
OBGZ33. 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.
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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.
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Protection Control
Good power supply system reliability is achieved
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 OBGZ33 is shut down when
VDD drops below UVLO (ON) and the power
converter enters power on start-up sequence
thereafter.
Figure.4. On time OCP compensation
Programmable Cable Drop Compensation
In OBGZ33, cable drop compensation is
implemented to achieve good load regulation. An
offset voltage is generated at INV pin by an
©On-Bright Electronics
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-8-
Preliminary Datasheet
OB_DOC_DS_GZ3300
OBGZ33
High Precision CC/CV Primary-Side Power Switch
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
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Symbol
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PACKAGE MECHANICAL DATA
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A1
A2
B
B1
C
D
E
E1
e
L
E2
©On-Bright Electronics
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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_GZ3300
OBGZ33
High Precision CC/CV Primary-Side Power Switch
Revision History
File name
Date
Update information
OB_DOC_DS_GZ3300
2016/08/31
First issue
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IMPORTANT NOTICE
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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.
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Preliminary Datasheet
OB_DOC_DS_GZ3300