PowerInt LCS700HG 100W高效LCD TV电源(DER282)方案

发布时间：2011-9-26 14:12 发布者：1046235000

关键词： DER282 , LCD , LCS700-708 , Powerint , TV电源

PowerInt公司的LCS700-708是集成了LLC控制器,高压功率MOSFET和驱动器的HiperLCS 系列产品,能节省30%的外接元件,最高工作频率达1MHz,正常稳定工作高达500kHz,大大降低了磁性元件SMD电容元件尺寸,满负载的效率大于94%,50%负载时大于93%,主要用在高效电源,LCD TV电源,LED街灯和区域照明,打印机电源和音频放大器.本文介绍了LCS700-708主要特性,方框图, LCD TV和PC主电源应用电路, 150W激光打印机电源电路以及采用HiperLCSTM LCS700HG 的100W小型LLC DC/DC转换器的主要特性和指标,电路图和材料清单,PCB布局图.

LCS700-708 :HiperLCS Family Integrated LLC Controller, High-Voltage Power MOSFETs and Drivers

The HiperLCS is an integrated LLC power stage incorporating a multi-function controller, high-side and low-side gate drivers, plus two power MOSFETs in a half-bridge configuration. Figure 1 shows a simplified schematic of a HiperLCS based power stage where the LLC resonant inductor is integrated into the transformer.

The variable frequency controller provides high efficiency by switching the power MOSFETs at zero voltage (ZVS), eliminating switching losses.

LCS700-708主要特性:

• LLC half-bridge power stage incorporating controller, high and low-side gate drives, and high-voltage power MOSFETs

• Eliminates up to 30 external components

• High maximum operating frequency of 1 MHz

• Nominal steady-state operation up to 500 kHz

• Dramatically reduces magnetics size and allows use of SMD ceramic output capacitors

• Precise duty symmetry balances output rectifier current, improving efficiency

• 50% ±0.3% typical at 300 kHz

• Comprehensive fault handling and current limiting

• Programmable brown-in/out thresholds and hysteresis

• Undervoltage (UV) and overvoltage (OV) protection

• Programmable over-current protection (OCP)

• Short-circuit protection (SCP)

• Over-temperature protection (OTP)

• Programmable dead-time for optimized design

• Programmable burst mode maintains regulation at no-load and improves light load efficiency

• Programmable soft-start time and delay before soft-start

• Accurate programmable minimum and maximum frequency limits

• Single package designed for high-power and high-frequency

• Reduces assembly cost and reduces PCB layout loop areas

• Simple single clip attachment to heat sink

• Exposed thermal pad connected to ground potential – no insulators required between package and heat sink

• Staggered pin arrangement for simple PC board routing and high-voltage creepage requirements

• Paired with HiperPFS PFC product gives complete, high efficiency, low part count PSU solutions

LCS700-708应用:

• High-efficiency power supplies (80 PLUS Silver, Gold and Platinum)

• LCD TV power supplies

• LED street and area lighting

• Printer power supplies

• Audio amplifier

图1. LCS700-708方框图

图2. LCS700-708应用电路图LCD TV和PC主电源

图3. LCS700-708应用电路图:150W激光打印机电源

设计案例(DER282):采用HiperLCSTM LCS700HG 的100W小型LLC DC/DC转换器

主要特性:

 Very low parts count

 Highly integrated solution for low parts count and small size

 Low cost SMD (D-PAK) output diodes eliminates cost of heat sink and mounting

 High operating frequency (270 kHz) reduces size and cost

 Enables use of ceramic output capacitors

 Reduces size of transformer, low profile EFD30 transformer used

 Burst Mode ensures no-load regulation

 High efficiency

 >94% at 100% load, >93% at 50% load

 Capacitive current sense for low power dissipation

For proper operation, the board must be used with a bulk capacitor of at least 10uF between the +380 V input and the input return placed directly across the terminals.

The board required an external bias supply of 12 V for operation. Do not apply a voltage greater than 15 V or IC damage will result.

This power supply has short-circuit protection, but no output overvoltage protection. Performing an overvoltage test by disabling the TL431 (U3) or optocoupler (U2) will cause the output voltage to rise sufficiently to break down the output Schottky rectifiers(D2-D3) and destroy them. Therefore this test should not be performed without adding overvoltage protection circuitry.

The burst mode feature may cause slightly higher ripple voltage at output typically under light load and high input voltage conditions. Burst mode -21 of the LCS700HG is selected for this design.Soft-start performance can be optimized by selecting appropriate value of capacitanceC3 depending on applicable specification.

This design uses surface mount Schottky diode rectifiers. Voltage de-rating requirements must be carefully evaluated for use of this design. Components with higher ratings should be substituted depending on de-rating requirements

This document is an engineering report describing a 12 V / 24 V, 100 W LLC DC-DC resonant converter utilizing a LCS700HG integrated LLC control/power stage IC. This power supply is intended for use in an LCD TV with LED back light. The board requires +12 VDC and +380 VDC inputs.