欢迎访问ic37.com |
会员登录 免费注册
发布采购

LNK302DG 参数 Datasheet PDF下载

LNK302DG图片预览
型号: LNK302DG
PDF下载: 下载PDF文件 查看货源
内容描述: 使用LinkSwitch -TN系列元件数最少,节能艾菲cient离线式开关IC [LinkSwitch-TN Family Lowest Component Count, Energy-Effi cient Off-Line Switcher IC]
分类和应用: 开关
文件页数/大小: 20 页 / 712 K
品牌: POWERINT [ Power Integrations ]
 浏览型号LNK302DG的Datasheet PDF文件第1页浏览型号LNK302DG的Datasheet PDF文件第2页浏览型号LNK302DG的Datasheet PDF文件第4页浏览型号LNK302DG的Datasheet PDF文件第5页浏览型号LNK302DG的Datasheet PDF文件第6页浏览型号LNK302DG的Datasheet PDF文件第7页浏览型号LNK302DG的Datasheet PDF文件第8页浏览型号LNK302DG的Datasheet PDF文件第9页  
LNK302/304-306  
The LinkSwitch-TN oscillator incorporates circuitry that  
introduces a small amount of frequency jitter, typically 4 kHz  
peak-to-peak, to minimize EMI emission. The modulation rate  
of the frequency jitter is set to 1 kHz to optimize EMI reduction  
for both average and quasi-peak emissions. The frequency  
jitter should be measured with the oscilloscope triggered at  
the falling edge of the DRAIN waveform. The waveform in  
Figure 4 illustrates the frequency jitter of the LinkSwitch-TN.  
Pin Functional Description  
DRAIN (D) Pin:  
Power MOSFET drain connection. Provides internal operating  
current for both start-up and steady-state operation.  
BYPASS (BP) Pin:  
Connection point for a 0.1 μF external bypass capacitor for the  
internally generated 5.8 V supply.  
Feedback Input Circuit  
FEEDBACK (FB) Pin:  
The feedback input circuit at the FB pin consists of a low  
impedancesourcefolloweroutputsetat1.65V.Whenthecurrent  
deliveredintothispinexceeds49μA,alowlogiclevel(disable)  
is generated at the output of the feedback circuit. This output  
is sampled at the beginning of each cycle on the rising edge of  
the clock signal. If high, the power MOSFET is turned on for  
thatcycle(enabled), otherwisethepowerMOSFETremainsoff  
(disabled). Since the sampling is done only at the beginning of  
each cycle, subsequent changes in the FB pin voltage or current  
during the remainder of the cycle are ignored.  
During normal operation, switching of the power MOSFET is  
controlled by this pin. MOSFET switching is terminated when  
a current greater than 49 μA is delivered into this pin.  
SOURCE (S) Pin:  
This pin is the power MOSFET source connection. It is also the  
ground reference for the BYPASS and FEEDBACK pins.  
P Package (DIP-8B)  
G Package (SMD-8B)  
5.8 V Regulator and 6.3 V Shunt Voltage Clamp  
D Package (SO-8C)  
The 5.8 V regulator charges the bypass capacitor connected to  
the BYPASS pin to 5.8 V by drawing a current from the voltage  
on the DRAIN, whenever the MOSFET is off. The BYPASS  
pin is the internal supply voltage node for the LinkSwitch-TN.  
When the MOSFET is on, the LinkSwitch-TN runs off of the  
energy stored in the bypass capacitor. Extremely low power  
consumption of the internal circuitry allows the LinkSwitch-TN  
tooperatecontinuouslyfromthecurrentdrawnfromtheDRAIN  
pin. A bypass capacitor value of 0.1 μF is sufcient for both  
high frequency decoupling and energy storage.  
S
S
S
S
1
2
8
7
1
2
8
7
BP  
FB  
S
S
S
S
6
5
BP  
FB  
3
4
4
D
5
D
3a  
3b  
PI-3491-120706  
In addition, there is a 6.3 V shunt regulator clamping the  
BYPASS pin at 6.3 V when current is provided to the BYPASS  
pin through an external resistor. This facilitates powering of  
LinkSwitch-TN externally through a bias winding to decrease  
the no-load consumption to about 50 mW.  
Figure 3. Pin Conguration.  
LinkSwitch-TN Functional  
Description  
BYPASS Pin Under-Voltage  
LinkSwitch-TNcombinesahighvoltagepowerMOSFETswitch  
withapowersupplycontrollerinonedevice.Unlikeconventional  
PWM(pulsewidthmodulator)controllers,LinkSwitch-TNuses  
a simple ON/OFF control to regulate the output voltage. The  
LinkSwitch-TN controller consists of an oscillator, feedback  
(sense and logic) circuit, 5.8 V regulator, BYPASS pin under-  
voltagecircuit,over-temperatureprotection,frequencyjittering,  
current limit circuit, leading edge blanking and a 700 V power  
MOSFET.TheLinkSwitch-TNincorporatesadditionalcircuitry  
for auto-restart.  
The BYPASS pin under-voltage circuitry disables the power  
MOSFET when the BYPASS pin voltage drops below 4.85 V.  
Once the BYPASS pin voltage drops below 4.85 V, it must rise  
back to 5.8 V to enable (turn-on) the power MOSFET.  
Over-Temperature Protection  
The thermal shutdown circuitry senses the die temperature.  
The threshold is set at 142 °C typical with a 75 °C hysteresis.  
Whenthedietemperaturerisesabovethisthreshold(142°C)the  
power MOSFET is disabled and remains disabled until the die  
temperature falls by 75 °C, at which point it is re-enabled.  
Oscillator  
The typical oscillator frequency is internally set to an average  
of 66 kHz. Two signals are generated from the oscillator: the  
maximum duty cycle signal (DCMAX) and the clock signal that  
indicates the beginning of each cycle.  
Current Limit  
ThecurrentlimitcircuitsensesthecurrentinthepowerMOSFET.  
When this current exceeds the internal threshold (ILIMIT), the  
3
Rev. I 11/08  
 复制成功!