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| 型号： | FSDL321 |
| 厂商： | Fairchild Semiconductor |
| 文件页数： | 10/20页 |
| 文件大小： | 0K |
| 描述： | IC SWIT PWM GREEN CM OVP HV 8DIP |
| 产品变化通告： | Passivation Layer Change 07/Dec/2007 |
| 标准包装： | 50 |
| 输出隔离： | 隔离 |
| 频率范围： | 45kHz ~ 55kHz |
| 输入电压： | 8 V ~ 20 V |
| 输出电压： | 650V |
| 功率（瓦特）： | 17W |
| 工作温度： | 25°C ~ 140°C |
| 封装/外壳： | 8-DIP（0.300"，7.62mm） |
| 供应商设备封装： | 8-DIP |
| 其它名称： | FSDL321_NL FSDL321_NL-ND |
FSDH321, FSDL321
Functional Description
1. Startup : In previous generations of Fairchild Power
Switches (FPS TM ) the Vstr pin had an external resistor to the
DC input voltage line. In this generation the startup resistor
is replaced by an internal high voltage current source and a
switch that shuts off when 15mS goes by after the supply
voltage, Vcc, gets above 12V. The source turns back on if
Vcc drops below 8V.
Vo
431
Vfb
FB
3
Cfb
Vcc
5uA
D1
Vref
0.9mA
D2
Vfb*
2.5R
R
OSC
Gate
driver
Vin,dc
V SD
OLP
Istr
Vstr
Figure 5. Pulse width modulation (PWM) circuit
Vcc
UVLO <8V
on
15m S After UVLO
start(>12V)
off
J-FET
4. Protection Circuit : The FPS TM has several protective
functions such as over load protection (OLP), over voltage
protection (OVP), abnormal over current protection
(AOCP), under voltage lock out (UVLO) and thermal shut-
down (TSD). Because these protection circuits are fully inte-
grated inside the IC without external components, the
reliability is improved without increasing cost. Once the
fault condition occurs, switching is terminated and the Sense
Figure 4. High voltage current source
2. Feedback Control : The FSDx321 employs current mode
control, shown in figure 5. An opto-coupler (such as the
H11A817A) and shunt regulator (such as the KA431) are
typically used to implement the feedback network. Compar-
ing the feedback voltage with the voltage across the Rsense
resistor plus an offset voltage makes it possible to control the
switching duty cycle. When the reference pin voltage of the
KA431 exceeds the internal reference voltage of 2.5V, the
H11A817A LED current increases, thus pulling down the
feedback voltage and reducing the duty cycle. This event
typically happens when the input voltage is increased or the
output load is decreased.
3. Leading edge blanking (LEB) : At the instant the inter-
nal Sense FET is turned on, there usually exists a high cur-
rent spike through the Sense FET, caused by the primary side
capacitance and secondary side rectifier diode reverse recov-
ery. Excessive voltage across the Rsense resistor would lead
to incorrect feedback operation in the current mode PWM
control. To counter this effect, the FPS TM employs a leading
edge blanking (LEB) circuit. This circuit inhibits the PWM
comparator for a short time (T LEB ) after the Sense FET is
turned on.
FET remains off. This causes Vcc to fall. When Vcc reaches
the UVLO stop voltage, 8V, the protection is reset and the
internal high voltage current source charges the Vcc capaci-
tor via the Vstr pin. When Vcc reaches the UVLO start volt-
age,12V, the FPS TM resumes its normal operation. In this
manner, the auto-restart can alternately enable and disable
the switching of the power Sense FET until the fault condi-
tion is eliminated.
4.1 Over Load Protection (OLP) : Overload is defined as
the load current exceeding a pre-set level due to an unex-
pected event. In this situation, the protection circuit should
be activated in order to protect the SMPS. However, even
when the SMPS is in the normal operation, the over load
protection circuit can be activated during the load transition.
In order to avoid this undesired operation, the over load pro-
tection circuit is designed to be activated after a specified
time to determine whether it is a transient situation or an
overload situation. In conjunction with the Ipk current limit
pin (if used) the current mode feedback path would limit the
current in the Sense FET when the maximum PWM duty
cycle is attained. If the output consumes more than this max-
imum power, the output voltage (Vo) decreases below the set
voltage. This reduces the current through the opto-coupler
LED, which also reduces the opto-coupler transistor current,
thus increasing the feedback voltage (Vfb). If Vfb exceeds
3V, the feedback input diode is blocked and the 5uA Idelay
current source starts to charge Cfb slowly up to Vcc. In this
condition, Vfb continues increasing until it reaches 6V, when
the switching operation is terminated as shown in figure 6.
The delay time for shutdown is the time required to charge
10
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相关代理商/技术参数 |
参数描述 |
|---|---|
| FSDL321L | 功能描述:电源开关 IC - 配电 FPS for DVDP/STB RoHS:否 制造商:Exar 输出端数量:1 开启电阻（最大值）:85 mOhms 开启时间（最大值）:400 us 关闭时间（最大值）:20 us 工作电源电压:3.2 V to 6.5 V 电源电流（最大值）: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOT-23-5 |
| FSDL321L_Q | 功能描述:电源开关 IC - 配电 FPS for DVDP/STB RoHS:否 制造商:Exar 输出端数量:1 开启电阻（最大值）:85 mOhms 开启时间（最大值）:400 us 关闭时间（最大值）:20 us 工作电源电压:3.2 V to 6.5 V 电源电流（最大值）: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOT-23-5 |
| FSDLC01G-S | 制造商:AXIOMTEK 制造商全称:AXIOMTEK 功能描述:Capacity: 128MB to 32GB |
| FSDLC128-S | 制造商:AXIOMTEK 制造商全称:AXIOMTEK 功能描述:Capacity: 128MB to 32GB |
| FSDLC16G-S | 制造商:AXIOMTEK 制造商全称:AXIOMTEK 功能描述:Capacity: 128MB to 32GB |
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