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LNK6775K 参数 Datasheet PDF下载

LNK6775K图片预览
型号: LNK6775K
PDF下载: 下载PDF文件 查看货源
内容描述: [IC OFFLINE SW PSR 12ESOP]
分类和应用: 光电二极管
文件页数/大小: 24 页 / 2266 K
品牌: POWERINT [ Power Integrations ]
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LinkSwitch-HP  
Remote On/Off and Fast AC Reset  
At power-up the current out of the FEEDBACK pin has to  
exceed the line undervoltage turn-on threshold (brown-in)  
current IFB(UVREF) = -250 mA (typ.) before switching is enabled.  
During normal operation switching is disabled if the FEEDBACK  
pin current falls below the line undervoltage turn-off threshold  
(brown-out) current IFB(UVOFF) = -100 mA (typ.) for at least 8  
consecutive switching cycles. After switching has ended, the  
device enters auto-restart. The applicable auto-restart off-  
period tAR(OFF)1 = 150 ms (typ.).  
The PROGRAM pin can be used to turn on/off the device  
remotely. If the voltage on the pin is set to 1.35 V externally, the  
device stops switching. After releasing the PROGRAM pin the  
PROGRAM pin device commences switching when the voltage  
drops below 0.535 V.  
500  
PROGRAM Pin Resistor Value  
450  
124 k  
78.7 kΩ  
400  
52.3 kΩ  
34.8 kΩ  
D
350  
VSEC  
NS  
VBUS  
23.2 kΩ  
15.0 kΩ  
10.0 kΩ  
300  
CO  
VO  
NP  
250  
200  
150  
100  
50  
VAUX  
NA  
RFB1  
D
S
BP  
T1  
CONTROL  
FB  
0
U1  
1
10  
100  
PD CP  
PROGRAM Pin Capacitor Value (nF)  
RFB2  
VFB  
Figure 6. Optional Shutdown Time Extension Programming.  
The PROGRAM pin can also be used to reset the device latch  
after a latching OVP or OTP event. If the voltage on the pin is  
set to 3.4 V externally, the device latch is reset. Once the  
voltage drops below 0.535 V, device will start switching.  
PI-6837-120312  
Figure 8. Indirect High-Voltage Bus Sensing.  
Switching is also stopped if the FEEDBACK pin current exceeds  
the line overvoltage threshold current IFB(OV) = -1.15 mA (typ.) for  
at least 2 consecutive switching cycles.  
110  
100  
90  
Current Limit Compensation Over Line  
The high-voltage bus is sensed by means of measuring the  
current out of the FEEDBACK pin during the MOSFET on-time.  
To limit available overload power over line the set current limit is  
compensated as shown in Figure 7. The compensation is  
disabled at peak currents below 50% of the set current limit,  
and is re-enabled at 62.5% of the set current limit.  
80  
70  
Soft-Start  
A digital soft-start is implemented to reduce component stress  
at power supply start-up. The internal reference voltage will ramp  
up to 2 V during tSOFT (typ. 15 ms) at start-up. The loop will  
typically close (output reaches regulation) during this time to  
ensure smooth output voltage rise.  
-150  
-300  
-450  
-600  
-750  
-900  
-1050 -1200  
FEEDBACK Pin Current During MOSFET On-Time  
Figure 7. Current Limit Compensation Over Line.  
Fault Filter  
This is the digital filter to handle all the fault conditions including  
line overvoltage, line undervoltage, output overvoltage, and  
output undervoltage, thermal shutdown as well as package  
level fault (pin open-circuit or pin-to-pin short-circuit).  
High-Voltage Bus Sensing  
LinkSwitch-HP senses indirectly the HV voltage bus VBUS during  
the power MOSFET on-time by monitoring the current flowing  
out of the FEEDBACK pin. During the MOSFET on-time the  
voltage across the auxiliary winding is proportional to the voltage  
across the input winding. The current flowing through resistor  
RFB1 (see Figure 8) is therefore representing VBUS. Indirect line  
sensing minimizes power dissipation and is used for line UV or  
line OV protection and current limit compensation over line.  
Transconductance Amplifier  
The controller uses a high gain (typ. 70 dB) transconductance  
amplifier to ensure exceptional output regulation.  
5
Rev. E 06/15  
www.power.com  
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