LNK362低功耗单火线开关芯片：优化系统成本与高效能解决方案

需积分: 17 191 浏览量更新于2024-07-22 1 收藏 758KB PDF 举报

"LNK362是一款专为低功耗应用设计的单火线电源芯片，常用于LED驱动。这款芯片具有多种优化功能，旨在降低系统成本、减少组件数量并提高能效。" LNK362是LinkSwitch-XT系列的一部分，这是一个高效、低功耗的离线开关集成电路家族。其典型应用包括与LinkSwitch-XT配合使用的电路设计，如图1所示。该芯片的主要特性如下： 1. 创新设计：LNK362采用独特的IC修剪和变压器构造技术，实现了无需钳位（Clampless）设计，这有助于降低成本、减少组件数量，并提高整体效率。 2. 全面保护：集成的自动重启动功能可应对短路和开路保护，确保系统的安全运行。 3. 自我偏置供电：此功能省去了变压器辅助绕组及相关的偏置供电组件，简化了电路设计。 4. 频率抖动：通过频率抖动技术大大降低了电磁干扰（EMI），符合高压爬电距离要求，同时在PCB板上和封装的所有引脚之间保持安全距离。 5. 最少的组件数量：LNK362是市场上组件最少的开关解决方案之一，提高了可靠性并简化了一侧印刷电路板的设计。 6. 优越于线性/RCC的特性：准确的恒热式热关断保护提供自动恢复功能，增强了现场可靠性；全球通用输入范围使其可在世界各地使用；简单的ON/OFF控制，无需环路补偿；消除了偏置绕组，使得变压器设计更简单、成本更低；极低的组件数量进一步提高了可靠性和单面PCB布局的可行性。 7. 自动重启动：自动重启动功能能够减少输送功率的9%，从而进一步优化了能效。 LNK362芯片适用于对能效和成本有严格要求的LED驱动和低功耗电源应用。其设计上的创新和优化特性，使得它成为解决单火线电源和LED驱动问题的理想选择，特别是在需要高效率、低成本和高可靠性的场合。

LNK362-364

12/05

Applications Example

A 2 W CV Adapter

The schematic shown in Figure 5 is a typical implementation of

a universal input, 6.2 V ±7%, 322 mA adapter using LNK362.

This circuit makes use of the Clampless technique to eliminate the

primary clamp components and reduce the cost and complexity

of the circuit.

The EcoSmart features built into the LinkSwitch-XT family

allow this design to easily meet all current and proposed

energy efﬁ ciency standards, including the mandatory California

Energy Commission (CEC) requirement for average operating

efﬁ ciency.

The AC input is rectiﬁ ed by D1 to D4 and ﬁ ltered by the bulk

storage capacitors C1 and C2. Resistor RF1 is a ﬂ ameproof,

fusible, wire wound type and functions as a fuse, inrush current

limiter and, together with the π ﬁ lter formed by C1, C2, L1

and L2, differential mode noise attenuator. Resistor R1 damps

ringing caused by L1 and L2.

This simple input stage, together with the frequency jittering of

LinkSwitch-XT, a low value Y1 capacitor and PIʼs E-Shield™

windings within T1, allow the design to meet both conducted

and radiated EMI limits with >10 dBµV margin. The low value

of CY1 is important to meet the requirement for a very low

touch current (the line frequency current that ﬂ ows through

CY1) often speciﬁ ed for adapters, in this case <10 µA.

The rectiﬁ ed and ﬁ ltered input voltage is applied to the primary

winding of T1. The other side of the primary is driven by the

integrated MOSFET in U1. No primary clamp is required as the

low value and tight tolerance of the LNK362 internal current

limit allows the transformer primary winding capacitance to

provide adequate clamping of the leakage inductance drain

voltage spike.

The secondary of the ﬂ yback transformer T1 is rectiﬁ ed by D5,

a low cost, fast recovery diode, and ﬁ ltered by C4, a low ESR

capacitor. The combined voltage drop across VR1, R2 and the

LED of U2 determines the output voltage. When the output

voltage exceeds this level, current will ﬂ ow through the LED

of U2. As the LED current increases, the current fed into the

FEEDBACK pin of U1 increases until the turnoff threshold

current (~49 µA) is reached, disabling further switching cycles

of U1. At full load, almost all switching cycles will be enabled,

and at very light loads, almost all the switching cycles will be

disabled, giving a low effective frequency and providing high

light load efﬁ ciency and low no-load consumption.

Resistor R3 provides 1 mA through VR1 to bias the Zener

closer to its test current. Resistor R2 allows the output voltage

to be adjusted to compensate for designs where the value of the

Zener may not be ideal, as they are only available in discrete

voltage ratings. For higher output accuracy, the Zener may be

replaced with a reference IC such as the TL431.

Figure 5. 2 W Universal Input CV Adapter Using LNK362.

1N4005

1N4934

PI-4162-110205

1N4005

RF1

8.2 Ω

2.5 W

3.9 k

1/8 W

1 k

1/8 W

390 Ω

1/8 W

6.2 V,

322 mA

85-265

VRMS

1 mH

3.3 µF

400 V

3.3 µF

400 V

CY1

100 pF

250 VAC

330 µF

16 V

VR1

BZX79-

B5V1

5.1 V, 2%

EE16

NC NC

100 nF

50 V

PC817A

LNK362P

LinkSwitch-XT

剩余15页未读，继续阅读

wtoangel

粉丝: 2
资源: 7

LNK362低功耗单火线开关芯片：优化系统成本与高效能解决方案

简化外围电路的高耐压开关电源芯片LNK302/304/306详解

LNK304PN：低成本、高效能离线开关IC

高性能3Wled驱动电源LNK303P：集成保护与低成本解决方案

使用LinkSwitchTM-HP LNK6766E设计的30 W单路输出反激式转换器

MSP430系列芯片简要介绍

MSP430系列芯片简要介绍.pdf

基于功率测量芯片FC7759的智能断电节能插座设计

单片机电源模块设计：高效LNK500充电器详解

基于LNK500的2.5W单片机电源模块设计与应用

LNK302-306:高效离线开关IC，简化电源设计

最新资源