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PDF OB2279 Data sheet ( Hoja de datos )
| Número de pieza | OB2279 | |
| Descripción | Current Mode PWM Controller | |
| Fabricantes | On-Bright | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de OB2279 (archivo pdf) en la parte inferior de esta página. Total 13 Páginas | ||
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OB2279
Current Mode PWM ControllerFreq Shuffling with Latch Shutdown
GENERAL DESCRIPTION
OB2279 is a highl y integ rated current mode PWM
control IC optimized fo r high performance, low
standby pow er and cost effe ctive offline fly back
converter applications.
PWM switching frequenc y at norm al operation is
externally programmable and trimmed to tigh t range.
At no load or light load condition, t he IC operates in
extended ‘bu rst mode’ to minimize switching loss.
Lower stan dby p ower and high er conversion
efficiency is thus achieved.
VDD low startup current and low operating curre nt
contribute to a reliable po wer on startu p design with
OB2279. A large value resistor could t hus be used i n
the startup circuit for reduced power loss.
The internal slope com pensation im proves sy stem
large signal stability and reduces the possible sub-
harmonic oscillation at high PWM dut y cycle output.
Leading-edge blankin g on current sense input
removes the signal glitch du e to snubber circuit diode
reverse r ecovery and greatly reduces the external
component count and system cost in the design.
OB2279 offers co mprehensive protection coverage
including Cy cle-by-Cycle current li miting(OCP),
VDD Under Voltage Lockout(UVLO), VDD Over
Voltage Protection(OVP), VDD Cl amp, Gate Cla mp,
Over Load protection(OLP) and Over Tem perature
protection (OTP), etc.
Different latch shutdown optio ns are offered on
OB2279 in d ifferent device version. V version has
OVP Latch shutdown . T v ersion supp orts both OVP
and OTP latch shutdown. L version provides all OVP,
OTP and OLP latch shutdown control.
Excellent EMI perform ance is achieved with On-
Bright pr oprietary freq uency shuffli ng techni que
together with soft switching control at the totem pole
gate drive output.
Tone energ y at below 20KHZ is minim ized in
operation. C onsequently, audio no ise is elim inated
during operation.
OB2279 is offered in SOP-8 and DIP-8 packages.
FEATURES
■ On-Bright Proprietary Frequency Shuffling
Technology for Improved EMI Performance
■ Power On Soft Start
■ Extended Burst Mode Control For Im proved
Efficiency and Minimum Standby Power Design
■ Audio Noise Free Operation
■ External P rogrammable PWM
Switching
Frequency
■ Internal Synchronized Slope Compensation
■ Low VIN/V DD Startup Current(3uA) and Low
Operating Current (2.3mA)
■ Leading Edge Blanking on Current Sense Input
■ Complete Protection Coverage with selectiv e
protections for Latch Shutdown
o VDD Ov er Voltage Protection(OVP) – Latch
Shutdown
o Over Tem perature Protection(OTP) – Auto
recovery or Latch Shutdown
o Over Load P rotection. (O LP) – Aut o r ecovery
or Latch Shutdown
o VDD Under Voltage Lockout with Hysteresis
(UVLO)
o Gate Output Voltage Clamp (16.5V)
o Built-in OCP Com pensation to Achieve
Minimum OPP Variation over Universal AC
Input Range.
APPLICATIONS
Offline AC/DC flyback converter for
■ Adaptor
■ Notebook Adaptor
■ LCD Monitor/TV/PC/Set-Top Box Power
Supplies
■ Open-frame SMPS
■ Printer Power
TYPICAL APPLICATION
©On-Bright Electronics
-1-
Confidential
OB_DOC_DS_79A0
http://www.Datasheet4U.com
1 page  
OB2279
Current Mode PWM ControllerFreq Shuffling with Latch Shutdown
ELECTRICAL CHARACTERISTICS
(TA = 25OC if not otherwise noted)
Symbol Parameter
Supply Voltage (VDD)
I_VDD_Startup VDD Start up Current
I_VDD_Ops Operation
Current
UVLO(Enter) VDD
Under Voltage
Lockout Enter
UVLO(Exit) VDD
Under Voltage
Lockout Exit
(Startup)
OVP(Latch)
VDD Over Voltage
Latch Trigger
OVP(De-Latch) VDD Latch Release
Voltage Threshold
I(Vdd)_latch
VDD bleeding current
at latch shutdown
when VDD = 9V
TD_OVP
VDD OVP Debounce
time
VDD_Clamp V
DD Zener Clamp
Voltage
T_Softstart
Soft Start Time
Feedback Input Section(FB Pin)
AVCS
PWM Input Gain
VFB_Open V
FB Open Voltage
Test Conditions
VDD =15V, RI=100K
Measure current into
VDD
VDD=16V,
RI=100Kohm, VFB=3V
26.5
RI = 100Kohm
RI = 100 Kohm, I(VDD ) =
5 mA
ΔVFB /ΔVcs
VDD = 16V
IFB_Short
FB pin short circuit
current
VTH_0D
Zero Duty Cycle FB
Threshold Voltage
VTH_BM
Burst Mode FB
Threshold Voltage
VTH_PL
Power Limiting FB
Threshold Voltage
TD_PL Power
limiting
Debounce Time
ZFB_IN Input
Impedance
Current Sense Input(Sense Pin)
T_blanking
Sense Input Leading
Edge Blanking Time
ZSENSE_IN Sense
Input
Impedance
TD_OC Over
Current
Detection and Control
Delay
VTH_OC_0 Current
Limiting
Threshold at No
Compensation
Short FB pin to GND,
measure current
VDD = 16V,
RI=100Kohm
VDD = 16V,
RI=100Kohm
RI = 100Kohm
CL=1nf at GATE,
RI=100Kohm
VDD = 16V, I(VIN) =
0uA, RI=100Kohm
Min Typ Max
3 20
2.3
8.8 9.8 10.8
15.5 16.5 17.5
28 29.5
7.5
45
80
35
3
2.8
6.2
0.75
0.95
1.6
4.4
80
9.0
300
30
70
V
0.85 0.90 0.95
Unit
uA
mA
V
V
V
V
uA
uSec
V
mSec
V/V
mA
V
V
V
mSec
Kohm
nSec
Kohm
nSec
V
©On-Bright Electronics
-5-
Confidential
OB_DOC_DS_79A0
5 Page 
OB2279
Current Mode PWM ControllerFreq Shuffling with Latch Shutdown
PACKAGE MECHANICAL DATA
8-Pin Plastic DIP
©On-Bright Electronics
- 11 -
Confidential
OB_DOC_DS_79A0
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet OB2279.PDF ] | |
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