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OB2535
High Precision CC/CV Primary-Side PWM Power Switch
GENERAL DESCRIPTION
OB2535 is a high performance offline PWM Power
switch for low power AC/DC charger and adaptor
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 as well at large
load condition and it operates in PWM with
frequency reduction at light/medium load.
OB2535 offers power on soft start control and
protection coverage with auto-recovery features
including Cycle-by-Cycle current limiting, VDD
OVP, VDD clamp and UVLO. Excellent EMI
performance is achieved with On-Bright proprietary
frequency shuffling technique.
High precision constant voltage (CV) and constant
current (CC) can be achieved by OB2535.
.
FEATURES
„ 5% Constant Voltage Regulation, 5% Constant
Current Regulation at Universal AC input
„ Primary-side Sensing and Regulation Without
TL431 and Opto-coupler
„ Programmable CV and CC Regulation
„ Adjustable Constant Current and Output Power
Setting
„ Built-in Secondary Constant Current Control
with Primary Side Feedback
„ Built-in Adaptive Current Peak Regulation
„ Built-in Primary winding inductance
compensation
„ Programmable Cable drop Compensation
„ Power on Soft-start
„ Built-in Leading Edge Blanking (LEB)
„ Cycle-by-Cycle Current Limiting
„ VDD Under Voltage Lockout with Hysteresis
(UVLO)
„ VDD OVP
„ VDD Clamp
APPLICATIONS
Low Power AC/DC offline SMPS for
„ Cell Phone Charger
„ Digital Cameras Charger
„ Small Power Adaptor
„ Auxiliary Power for PC, TV etc.
„ Linear Regulator/RCC Replacement
OB2535 is offered in SOP8 package.
Fig.1. Typical CC/CV Curve
TYPICAL APPLICATION
©On-Bright Electronics
-1-
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OB2535
High Precision CC/CV Primary-Side PWM Power Switch
GENERAL INFORMATION
Pin Configuration
The pin map is shown as below for SOP8
Package Dissipation Rating
Package
RθJA (/W)
SOP8
90
Note: Drain Pin Connected 100mm2 PCB copper
clad.
VDD 1
8 GND
COMP 2
7 GND
INV 3
6 DRAIN
CS 4
5 DRAIN
Ordering Information
Part Number
Description
OB2535CP
SOP8, Pb-free, Tube
OB2535CPA
SOP8, Pb-free, T&R
Absolute Maximum Ratings
Parameter
Value
Drain Voltage (off state) -0.3V to Bvdss
VDD Voltage
-0.3 to VDD_clamp
VDD Zener Clamp
10 mA
Continuous Current
COMP Voltage
-0.3 to 7V
CS Input Voltage
-0.3 to 7V
INV Input Voltage
-0.3 to 7V
Min/Max Operating
-20 to 150 oC
Junction Temperature TJ
Min/Max Storage
-55 to 150 oC
Temperature Tstg
Lead Temperature
260 oC
(Soldering, 10secs)
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.
©On-Bright Electronics
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Marking Information
OB2535
High Precision CC/CV Primary-Side PWM Power Switch
OB2535CP
YWW
S
C:SOP8 Package
P:Pb-free Package
Y:Year Code(0-9)
WW:Week Code(01-52)
S:Internal Code(Optional)
TERMINAL ASSIGNMENTS
Pin Num Pin Name
1 VDD
2 COMP
3 INV
4 CS
5/6 DRAIN
7/8 GND
I/O Description
P Power Supply
I Loop Compensation for CV Stability
The voltage feedback from auxiliary winding. Connected to resistor divider
I from auxiliary winding reflecting output voltage. PWM duty cycle is
determined by EA output and current sense signal at pin 4.
I Current sense input
O
HV MOSFET Drain Pin. The Drain pin is connected to the primary lead of
the transformer
P Ground
OUTPUT POWER TABLE
Product
OB2535
230VAC±15%
Adapter1
6W
85-264VAC
Adapter1
5W
Notes:
1. Maximum practical continuous power in an Adapter design with sufficient drain pattern as a heat sink, at 50ambient.
©On-Bright Electronics
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OB2535
High Precision CC/CV Primary-Side PWM Power Switch
BLOCK DIAGRAM
VDD 1
POR
UVLO
Internal
5V Supply
Gate
Driver
DRAIN
5/6
Power
MOSFET
CC
Controller
Drop
Comp
2V
INV
3 Sampler
EA
PWM
Generator
CLK
Genterator
Sampling
Controller
Frequency
Shuffling
2 COMP
Soft start
OCP
LEB
CS
4
GND
7/8
©On-Bright Electronics
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OB2535
High Precision CC/CV Primary-Side PWM Power Switch
ELECTRICAL CHARACTERISTICS
(TA = 25OC, VDD=VDDG=16V, if not otherwise noted)
Symbol
Parameter
Test Conditions
Min Typ Max Unit
Supply Voltage (VDD) Section
I DD ST
Standby Current
VDD=13V
5 20 uA
I DD op
Operation Current
Operation supply current
INV=2V, CS=0V,
-
VDD=VDDG=20V
2.5 3.5
mA
UVLO(ON)
VDD Under Voltage
Lockout Enter
VDD falling
7.5 8.5 10
V
UVLO(OFF)
VDD Under Voltage
Lockout Exit
VDD rsing
13.5 14.5 16.0 V
VDD_clamp
Maximum VDD operation
voltage
IDD=10mA
30.5 32.5 345 V
OVP
Over voltage protection
Threshold
Ramp VDD until gate
shut down
27.5 29.5 31.5 V
Current Sense Input Section
TLEB
LEB time
540 ns
Vth_oc
Over current threshold
870 900 930 mV
Td_oc
OCP Propagation delay
150 ns
ZSENSE_IN
T_ss
Input Impedance
Soft start time
50 Kohm
10 ms
Frequency Section
Freq_MaxNote 1
IC Maximum frequency
66 72 78
KHz
Freq_Nom
System Nominal switch
frequency
60 KHz
Freq_startup
INV=0V, Comp=5V 14 KHz
f/Freq
Frequency shuffling range
+/-4 %
Error Amplifier section
Vref_EA
Reference voltage for EA
1.97 2
2.03 V
Gain DC gain of EA
60 dB
I_COMP_MAX
Max. Cable compensation
current
INV=2V, Comp=0V
42
uA
Power MOSFET Section
BVdss
MOSFET Drain-Source
Breakdown Voltage
600 V
Rdson
On Resistance
Static, Id=0.4A
12 15
Ώ
Note:
1. Freq_Max indicates IC internal maximum clock frequency. In system application, the maximum operation
frequency of 60Khz nominal occurs at maximum output power or the transition point from CV to CC.
©On-Bright Electronics
-5-
Confidential
OB_DOC_DS_253502