High Performance QR mode Primary-Side Power Switch
OB2571x
GENERAL DESCRIPTION
OB2571x is an excellent primary side regulation
controller with CC/CV operation for medium level
power AC/DC charger and adapter applications.
The device integrates an internal power MOSFET
and operates in QR mode to provide high
efficiency along with several functions of built-in
protections. It removes the need for secondary
feedback circuitry to lower the total bill of material
cost. Proprietary Constant Voltage (CV) and
Constant Current (CC) control is integrated as
shown in the figure below.
In CV control, the controller changes the mode of
operation according to load condition. At full
loading, the controller operates in quasi-resonant
(QR) mode in the universal line voltage. The
primary side regulation power supplies up to high
power without the efficiency limitation of DCM or
audible noise.
In CC control, OB2571x samples the Vcs peak
current and the demagnetization pulse to
regulation the output current. The current and
output power setting can be adjusted externally by
the sense resistor Rs at CS pin.
OB2571x offers comprehensive protection
coverage with auto-recovery feature including
Cycle-by-Cycle current limiting, VDD OVP, OLP,
SCP, OTP etc.
OB2571x consumes less than 75mW input power
at no- load condition with high line voltage.
OB2571x is offered in SOP8 package.
FEATURES
Primary-side sensing and regulation operates
in QR mode without TL431 and opto-coupler
High precision constant voltage and current
regulation at universal AC input
Programmable CV and CC regulation
Integrated power MOSFET
Good dynamic response
Programmable Brownout Protection and Line
OVP Protection(For 2571Lx only)
Built-in line compensation for tight CC
regulation
Built-in fixed cable compensation
Built-in primary winding inductance
compensation
Built-in control loop compensation
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 OVP)
VDD under voltage lockout with
hysteresis (UVLO)
Cycle-by-cycle current limiting
Feedback open loop protection (OLP)
Output short circuit protection (SCP)
APPLICATIONS
Medium level Power AC/DC offline SMPS for
Cell phone charger
Tablet PC
AC/DC adapter
Set-top box power supplies
Figure.1. Typical CC/CV Curve
TYPICAL APPLICATION
©On-Bright Electronics
Confidential
-1-
Datasheet
OB_DOC_DS_2571xA0
High Performance QR mode Primary-Side Power Switch
OB2571x
GENERAL INFORMATION
Pin Configuration
The pin map is shown as below for SOP8.
Absolute Maximum Ratings
Parameter
VDD Voltage
FB Input Voltage
Drain Voltage (off state)
CS Input Voltage
Min/Max Operating Junction
Temperature T
J
Operating
Ambient
Temperature T
A
Min/Max
Storage
Temperature T
stg
Lead
Temperature
(Soldering, 10secs)
Value
-0.3 to 30V
-0.3 to 7V
-0.3 to Bvdss
-0.3 to 7V
-40 to 150
℃
-20 to 85
℃
-55 to 150
℃
260
℃
VDD
FB
GND
CS
1
2
3
4
8
7
6
5
DRAIN
DRAIN
DRAIN
DRAIN
Ordering Information
Part Number
Description
OB2571TCP
SOP8, Halogen-free in Tube
OB2571TCPA
SOP8, Halogen-free in T&R
OB2571ATCP-H
SOP8, Halogen-free in Tube
OB2571ATCPA-H
SOP8, Halogen-free in T&R
OB2571LTCP-H
SOP8, Halogen-free in Tube
OB2571LTCPA-H
SOP8, Halogen-free in T&R
OB2571ALTCP
SOP8, Halogen-free in Tube
OB2571ALTCPA
SOP8, Halogen-free in T&R
Package Dissipation Rating
Package
RθJA (℃/W)
SOP8
85
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.
Recommended Operating Condition
Symbol
Parameter
Range
VDD
VDD Supply Voltage
9 to 25V
OB2571x
X
X
X
- X
High Performance QR mode
Primary-Side Power Switch
Package
C:SOP8
Package Green
P:Halogen-free
Packing
BVdss
Blank:Tube
H:650V
A: Tape/Reel
©On-Bright Electronics
Confidential
-2-
Datasheet
OB_DOC_DS_2571xA0
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