参数资料
| 型号： | LNK501P |
| 厂商： | Power Integrations |
| 文件页数： | 6/20页 |
| 文件大小： | 0K |
| 描述： | IC SWIT OCP CV/CC HV 8DIP |
| 标准包装： | 3,000 |
| 系列： | LinkSwitch® |
| 输出隔离： | 隔离 |
| 频率范围： | 26kHz ~ 46kHz |
| 输出电压： | 700V |
| 功率（瓦特）： | 4W |
| 工作温度： | -40°C ~ 150°C |
| 封装/外壳： | 8-DIP（0.300"，7.62mm），7 引线 |
| 供应商设备封装： | DIP-8B |
| 包装： | 管件 |
| 配用： | 596-1001-ND - KIT DESIGN ACCELERATOR ADAPTER |
LNK501
However, in laboratory bench tests, it is often more convenient
to test the power supply output characteristic starting from a
low output current and gradually increasing the load. In this
case, the optocoupler feedback regulates the output voltage until
the peak output power curve is reached as shown in Figure 8.
Under these conditions, the output current will continue to rise
until the peak power point is reached and the optocoupler turns
off. Once the optocoupler is off, the CONTROL pin feedback
current is determined only by R1 and R3 and the output current
therefore folds back to the inherent CC characteristic as shown.
Since this type of load transition does not normally occur in a
battery charger, the output current never overshoots the inherent
constant current value in the actual application.
In some applications it may be necessary to avoid any output
current overshoot, independent of the direction of load variation.
To achieve this goal, the minimum voltage feedback threshold
should be set at V O(MAX) . This will ensure that the voltage at the
CC to CV transition point of the inherent characteristic will
always occur below the voltage feedback threshold. However, the
output voltage tolerance is then increased, since the inherent CV
characteristic tolerance below V O(MAX) is added to the tolerance
of the optocoupler feedback circuit.
Applications Example
The circuit shown in Figure 9 shows a typical implementation
of an approximate constant voltage / constant current (CV/CC)
charger using LinkSwitch . This design delivers 2.75 W with
a nominal peak power point voltage of 5.5 V and a current of
500 mA. Ef?ciency is greater than 70% over an input range
of 85 VAC to 265 VAC.
The bridge recti?er, BR1, recti?es the AC input. Resistor RF1
is a fusible type providing protection from primary side short
circuits. The recti?ed AC is smoothed by C1 and C2 with
inductor L1 forming a pi-?lter in conjunction with C1 and C2
to ?lter conducted EMI. The switching frequency of 42 kHz
allows such a simple EMI ?lter to be used without the need for
a Y capacitor while still meeting international EMI standards.
When power is applied, high voltage DC appears at the DRAIN
pin of LinkSwitch (U1). The CONTROL pin capacitor C3 is
then charged through a switched high voltage current source
connected internally between the DRAIN and CONTROL pins.
When the CONTROL pin reaches approximately 5.6 V relative
to the SOURCE pin, the internal current source is turned off. The
internal control circuitry is activated and the high voltage MOSFET
starts to switch, using the energy in C3 to power the IC.
When the MOSFET is on, the high voltage DC bus is connected
to one end of the transformer primary, the other end being
connected to primary return. As the current ramps in the
primary of ?yback transformer T1, energy is stored. This
energy is delivered to the output when the MOSFET turns off
each switching cycle.
The secondary of the transformer is recti?ed and ?ltered by D6
and C5 to provide the DC output to the load.
LinkSwitch dramatically simpli?es the secondary side by
controlling both the constant voltage and constant current regions
entirely from the primary side. This is achieved by monitoring
the primary-side V OR (voltage output re?ected).
Diode D5 and capacitor C4 form the primary clamp network.
This both limits the peak drain voltage due to leakage inductance
and provides a voltage across C4, which is equal to the V OR plus
an error due to the parasitic leakage inductance. Resistor R2
?lters the leakage inductance spike and reduces the error in the
value of the V OR . Resistor R1 converts this voltage into a current
that is fed into the CONTROL pin to regulate the output.
During CV operation the output is regulated through control of
the duty cycle. As the current into the CONTROL pin exceeds
approximately 2 mA, the duty cycle begins to reduce, reaching
30% at a CONTROL pin current of 2.3 mA.
Under light or no-load conditions, when the duty cycle reaches
approximately 4%, the switching frequency is reduced to lower
energy consumption.
If the output load is increased beyond the peak power point
(de?ned by 0.5·L P ·I LIM2 ·f), the output voltage and V OR falls.
The reduced CONTROL pin current will lower the internal
LinkSwitch current limit (current limit control) providing an
approximately constant current output characteristic. If the
load is increased and the CONTROL pin current falls below
approximately 1 mA, the CONTROL pin capacitor C3 will
discharge and the supply enters auto-restart.
Current limit control removes the need for any secondary side
current sensing components (sense resistor, transistor, opto
coupler and associated components). Removing the secondary
sense circuit dramatically improves ef?ciency, giving the
associated bene?t of reduced enclosure size.
Key Application Considerations
Design Output Power
Table 1 (front page) shows the maximum continuous output
power that can be obtained under the following conditions:
1. The minimum DC input bus voltage is 90 V or higher.
This corresponds to a ?lter capacitor of 3 μ F/W for
universal input and 1 μ F/W for 230 VAC or 115 VAC
input with doubler input stage.
2. Design is a discontinuous mode ?yback converter, with
nominal primary inductance value and a V OR in the range
40 V to 60 V. Continuous mode designs can result in loop
instability and are therefore not recommended.
6
I
2/05
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LNK501P_1 | 制造商:POWERINT 制造商全称:Power Integrations, Inc. 功能描述:2.2W Cell Phone Charger |
| LNK501PN | 功能描述:交流/直流开关转换器 3W 85-265 VAC 4W 230 VAC RoHS:否 制造商:STMicroelectronics 输出电压:800 V 输入/电源电压（最大值）:23.5 V 输入/电源电压（最小值）:11.5 V 开关频率:115 kHz 电源电流:1.6 mA 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:SSO-10 封装:Reel |
| LNK520 | 制造商:POWERINT 制造商全称:Power Integrations, Inc. 功能描述:Energy Efficient, CV or CV/CC Switcher for Very Low Cost Adapters and Chargers |
| LNK520G | 功能描述:IC SWIT OCP CV/CC HV 8SMD RoHS:否 类别:集成电路 (IC) >> PMIC - AC-DC 转换器，离线开关 系列:LinkSwitch® 标准包装:1 系列:FPS™ 输出隔离:隔离 频率范围:61kHz ~ 73kHz 输入电压:8 V ~ 26 V 输出电压:650V 功率（瓦特）:12W 工作温度:-40°C ~ 115°C 封装/外壳:8-DIP（0.300"，7.62mm） 供应商设备封装:8-MDIP 包装:Digi-Reel® 其它名称:FSL206MRBNFSDKR |
| LNK520GN | 功能描述:交流/直流开关转换器 3W 85-265 VAC 4W 230 VAC RoHS:否 制造商:STMicroelectronics 输出电压:800 V 输入/电源电压（最大值）:23.5 V 输入/电源电压（最小值）:11.5 V 开关频率:115 kHz 电源电流:1.6 mA 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:SSO-10 封装:Reel |
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