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OB2278 の電気的特性と機能

OB2278のメーカーはOn-Brightです、この部品の機能は「Current Mode PWM Controller」です。


製品の詳細 ( Datasheet PDF )

部品番号 OB2278
部品説明 Current Mode PWM Controller
メーカ On-Bright
ロゴ On-Bright ロゴ 




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OB2278 Datasheet, OB2278 PDF,ピン配置, 機能
GENERAL DESCRIPTION
OB2278 is a highly integrated current mode PWM
control IC optimized for high performance, low
standby power and cost effective offline flyback
converter applications.
PWM switching frequency at normal operation is
externally programmable and trimmed to tight
range. At no load or light load condition, the IC
operates in extended ‘burst mode’ to minimize
switching loss. Lower standby power and higher
conversion efficiency is thus achieved.
VDD low startup current and low operating current
contribute to a reliable power on startup design
with OB2278. A large value resistor could thus be
used in the startup circuit for reduced power loss.
The internal slope compensation improves system
large signal stability and reduces the possible
sub-harmonic oscillation at high PWM duty cycle
output. Leading-edge blanking on current sense
input removes the signal glitch due to snubber
circuit diode reverse recovery and greatly reduces
the external component count and system cost in
the design.
OB2278 offers comprehensive protection
coverage including Cycle-by-Cycle current
limiting(OCP),
VDD
Under
Voltage
Lockout(UVLO),
VDD
Over
Voltage
Protection(OVP), VDD Clamp, Gate Clamp, Over
Load protection(OLP) and Over Temperature
protection (OTP), etc.
Different latch shutdown options are offered on
OB2278 in different device version. T version
supports both OVP and OTP latch shutdown. L
version provides all OVP, OTP and OLP latch
shutdown control.
Excellent EMI performance is achieved with soft
switching control at the totem pole gate drive
output.
OB2278 is offered in SOP-8 and DIP-8 packages.
TYPICAL APPLICATION
OB2278
Current Mode PWM ControllerLatch Shutdown
Product Specification
FEATURES
Power On Soft Start
Extended Burst Mode Control For Improved
Efficiency and Minimum Standby Power
Design
Audio Noise Free Operation
External Programmable PWM Switching
Frequency
Internal Synchronized Slope Compensation
Low VIN/VDD Startup Current(3uA) and Low
Operating Current (2.3mA)
Leading Edge Blanking on Current Sense
Input
Complete Protection Coverage with selective
protections for Latch Shutdown
o VDD Over Voltage Protection(OVP) – Latch
Shutdown
o Over Temperature Protection(OTP) – Latch
Shutdown
o Over Load Protection. (OLP) – Auto
recovery or Latch Shutdown
o VDD Under Voltage Lockout with Hysteresis
(UVLO)
o Gate Output Voltage Clamp (16.5V)
o Built-in OCP Compensation 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
©On-Bright Electronics
Confidential
-1-
Datasheet
OB_DOC_DS_2278A2

1 Page





OB2278 pdf, ピン配列
Marking Information
OB2278
Current Mode PWM ControllerLatch Shutdown
TERMINAL ASSIGNMENTS
Pin Num
1
2
Pin Name
GND
FB
3 VIN
4 RI
5 RT
6 SENSE
7 VDD
8 GATE
I/O Description
P Ground
I
Feedback input pin. PWM duty cycle is determined by voltage level into
this pin and current-sense signal level at Pin 6.
I
Connected through a large value resistor to rectified line input for startup
and line voltage sensing.
I
Internal oscillator frequency setting pin. A resistor connected between RI
and GND sets the PWM frequency.
Dual function pin. Either connected through a NTC resistor to GND for
I over temperature shutdown control or used as latch shutdown control
input.
I
Current sense input pin. Connected to MOSFET current sensing resistor
node.
P DC power supply pin.
O Totem-pole gate drive output for power MOSFET.
©On-Bright Electronics
Confidential
-3-
Datasheet
OB_DOC_DS_2278A2


3Pages


OB2278 電子部品, 半導体
OB2278
Current Mode PWM ControllerLatch Shutdown
RI_range
V_RI_open
F_BM
Operating RI Range
RI open voltage
Burst Mode Base
Frequency
Gate Drive Output
VOL
Output Low Level
VOH
Output High Level
VG_Clamp
T_r
T_f
Output Clamp Voltage
Level
Output Rising Time
Output Falling Time
Over Temperature Protection
I_RT
Output Current of RT pin
VTH_OTP
OTP Threshold Voltage
TD_OTP
OTP De-bounce Time
V_RT_Open
RT Pin Open Voltage
Io = 20 mA
Io = 20 mA
CL = 1nf
CL = 1nf
50 100 250 Kohm
2.0 V
20 KHZ
0.3 V
11 V
16.5 V
120 nSec
50 nSec
1.015
70
1.065
100
3.7
1.115
uA
V
uSec
V
©On-Bright Electronics
Confidential
-6-
Datasheet
OB_DOC_DS_2278A2

6 Page



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共有リンク

Link :


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