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| 主题：可攜式產品的燈光管理 | ||
| 在线问答： | ||
| [主持人：ChinaECNet] | 各位聽眾（網友），上午好！歡迎參加中電網線上座談。今天，我們有幸邀請到美國國家半導體公司的專家就“可攜式產品的燈光管理”舉行線上座談。在座談中，您可就您關心的問題與美國國家半導體公司的專家線上進行直接、即時的對話交流。中電網衷心希望通過大家的共同努力，不僅能夠增進各位聽眾（網友）對“可攜式產品的燈光管理”的瞭解和掌握，而且能夠為大家事業的發展帶來裨益。 | [2007-6-27 10:39:07] |
| [问：sduboy] | 美國國家半導體開發的發光二極體驅動晶片其電流匹配精度达到多少？ | |
| [答：rickzhong] | National Semiconductor has best technology on current matching control in industry. Our latest product can guarantee 0.3% current matching. | [2007-6-27 10:40:44] |
| [问：vicliang] | 如果以LM3405作為可攜式產品的燈光管理，有方法控制閃或50%亮度 | |
| [答：samting] | LM3405 has a EN pin, Enable control input. Logic high enables operation. Toggling this pin with a periodic logic square wave of varying duty cycle at different frequencies controls the brightness of LEDs. | [2007-6-27 10:41:47] |
| [主持人：ChinaECNet] | 各位聽眾（網友），上午好！歡迎參加中電網線上座談。今天，我們有幸邀請到美國國家半導體公司的專家就“可攜式產品的燈光管理”舉行線上座談。在座談中，您可就您關心的問題與美國國家半導體公司的專家線上進行直接、即時的對話交流。中電網衷心希望通過大家的共同努力，不僅能夠增進各位聽眾（網友）對“可攜式產品的燈光管理”的瞭解和掌握，而且能夠為大家事業的發展帶來裨益。 | [2007-6-27 10:43:46] |
| [主持人：ChinaECNet] | 我們已經進入問答階段如果聽眾想重溫演講或內容可以點擊下面“回顧演示”重看演講。 | [2007-6-27 10:44:47] |
| [主持人：ChinaECNet] | 在此回答問題的專家是美國國家半導體公司的：Henry Law、David Shaw、Alan Chang、Rick Zhong、Robert Shen、Janet Wu、Sam Ting和Stella Wong。 | [2007-6-27 10:45:21] |
| [问：vicliang] | 以LM3405作為可攜式產品的燈光管理，當使用AA電池5顆是否適用DC5V或需採DC12電路，還是有更好的電路。 | |
| [答：alanchang] | LM3405 Vin is 3~15V. In case 5 cells of AA battery, Vin = 1.5V*5 = 7.5V typical, but at min. Vin = 1.0*5 =5V. So, your input voltage is in range of LM3405. You don"t care which 12V or 5V circuit. Be aware of the voltage between Boost to SW pin less than 5V. | [2007-6-27 10:45:50] |
| [问：xl_cumt] | 1.不同LED使用不同的电压及电流驱动，驱动芯片如何做到良好的兼容性？ 2.受到体积的限制，便携产品往往不易加较大容量的电解电容，使用钽电容又比较贵，驱动芯片如何做到良好的驱动曲线，减少对LED的电压冲击，延长LED的使用寿命？ 3.驱动芯片的功效可达多少，效率高可延长电池的使用时间？ | |
| [答：rickzhong] | 1：我们的LED驱动芯片提供比较宽的电流电压输出范围，并且提供很多产品型号，支持不同的LED组合应用； 2：我们的大部分产品可以配合陶瓷电容工作； 3：不同的驱动芯片的效率表现不同。通常我们的电感式驱动芯片可以达到80%以上的效率，开关电容式驱动芯片可以达到75%的平均效率； | [2007-6-27 10:47:37] |
| [问：sduboy] | 如何实现大電流應用的電流安全控制？ | |
| [答：samting] | In general, would suggest using switching regulator instead of current regulator for efficiency / thermal concerns. For 1W HB LED app, NS has LM3402. For 3W HB LED app, NS has LM3404 and LM3405. | [2007-6-27 10:50:57] |
| [问：divaashiu] | LED和OLED亮度控制上有什麽差別?NS有那些産品特別適合於OLED? | |
| [答：rickzhong] | 我们的驱动芯片提供LED驱动和OLED的偏压。LED的亮度由驱动芯片的输出电流决定。而oled的亮度由oled控制电路决定。 | [2007-6-27 10:51:28] |
| [问：divaashiu] | 爲了降低PWM控制時的音頻噪音,PWM的頻率最低要多高?這種音頻噪音和那些因素有關? | |
| [答：janetwu] | Thanks for your interest in National"s product. With regard to your question, we would suggest you to specify the part number you"re interested in as well as your application. We will recommend our design solution base on information you provided. If you have more question in the future, you can also go to our website and submit feedback to our Technical Support. | [2007-6-27 10:51:31] |
| [问：simao310] | 用來控制數碼相機閃光燈的電源,和普通LED背光電源相比,有些什麽特色?NS有那些型號? | |
| [答：alanchang] | Flash LED needs big current (>500mA) than generic backlight LED (20mA per LED). And flash LED ON time is very small (<0.5S). National Semiductor has many parts such as:LM2754, LP5527/26, LP3936, LP3933 etc. | [2007-6-27 10:51:58] |
| [问：wangbfa] | 1.有没有驱动RGB背光LED的驱动芯片，要求大电流(350MA以上)，多数量(大于50个) 2.RGB背光LED的颜色如何保证和调整 | |
| [答：robertshen] | 1.50个以上的要用串联，或并联。要看具体组合。 2.RGB的颜色调节是通过分别调节R,G和B | [2007-6-27 10:56:52] |
| [问：wangbfa] | 1.如何选择适合RGB背光的LED，请介绍有关公司。 2.RGB背光与白光背光的光导板有差别否？请介绍有关公司。 | |
| [答：davidshaw] | 1. Taiwan Everlight 2. Yes, they are different. You could choose 3M | [2007-6-27 10:57:11] |
| [问：lulu2890] | 请问为了实现并行和串行解决方案，应选择不同型号的的LED驱动器吗？ | |
| [答：henrylaw] | Yes, like LM27966 and LM3508 from National Semiconductor. | [2007-6-27 10:59:20] |
| [问：wooda] | 请问便携产品中背光如果是10个白光二极管会有大约38V左右的背光电压, 这个电压在升压处理里面要注意什么问题? 对周边元件的干扰是不是很大? | |
| [答：rickzhong] | 如果是10个LED的串联方式，那么LED的回路的电压有机会高达30V以上，在设计中需要选择能提供相应电压的升压器件。在外围器件的选择是也要注意器件的耐压范围。通常电感式的驱动电路的EMI比开关电容式的驱动电路更难控制。 | [2007-6-27 10:59:22] |
| [问：zhm1977] | 請專家解釋一下LP5527中的Audio Syn是如何實現的? | |
| [答：henrylaw] | Taking the input signal from audio system like LM49370 and fit into our audio input pin in LP5527, then you can program the LP5527 to synchronize with the audio signal"s ampitude or frequency. | [2007-6-27 11:00:58] |
| [问：vicliang] | LM3405以EN PIN控制亮貴司有沒建議頻率或振幅 | |
| [答：samting] | Amplitude: The operating rating of EN/DIM pin is -0.5V to (VIN + 0.3V). Frequency: The applicable frequency range to drive LM3405 for PWM dimming is from 100Hz to 5kHz. | [2007-6-27 11:01:49] |
| [问：孫槿] | 請問1% current matching是指什麼意思呢? 能不能進一步說明, 或舉例, 謝謝. | |
| [答：rickzhong] | current matching 是指并联的led回路之间的电流一致程度。1%就是电路差异在1%以内。current matching 的值越低，led的亮度均匀度越好。 | [2007-6-27 11:02:05] |
| [问：lulu2890] | 什么是电感式升压转换器，有什么作用？ | |
| [答：janetwu] | There"re different configuration for LED driver and inductor based white LED driver is one type. It offers the highest efficiency, lowest noise, and the smallest footprints. | [2007-6-27 11:03:02] |
| [问：Guanjunren] | 不同颜色的LED在相同条件下驱动亮度并不相同，这个问题有没有好的方法？ | |
| [答：robertshen] | 只有靠程序补偿调整LED的差异性 | [2007-6-27 11:03:24] |
| [问：xcsunsz] | 请简介一下电流吸入式LED驱动器，谢谢！ | |
| [答：henrylaw] | LM27952 and LM27953 from National Semiconductor. | [2007-6-27 11:03:49] |
| [问：ivy8982] | 想请教一下,如何测量发光二极管的电流 | |
| [答：janetwu] | 发光二极管的特性是非线性的,特性曲线可以参考器件手册. 实验中,可以使用数字电压表连接二极管,串联1K可调电阻和电流表后接0-5V直流电源.调整电压或者电阻可以找出电流电压关系曲线. 交流电路中,使用万用表测量是不行的.可以使用示波器按测量直流电路中的方法进行测量,读数要从示波器上进行. | [2007-6-27 11:04:23] |
| [问：zirconsdu] | LED的短路和开路会对电路造成损害,请问专家:NS的LED驱动芯片有什么保护措施吗? | |
| [答：rickzhong] | LED的短路有可能引起输出多流，开路有可能引起输出过压。NS 的很多产品都具备过流过压保护功能。 | [2007-6-27 11:04:24] |
| [主持人：ChinaECNet] | 各位觀眾，現在用戶提問很踴躍，專家正在逐一回答。請耐心等待您問題的答案，同一問題請不要多次提交。 | [2007-6-27 11:05:40] |
| [问：sszzjj] | 驱动芯片如何才能做到良好的兼容性？ | |
| [答：rickzhong] | 驱动芯片的应该具备比较宽的输出电压，电流范围，以配合不同的LED。 | [2007-6-27 11:05:41] |
| [问：zirconsdu] | PWM做亮度控制会产生调制噪声，请问专家有什么有效措施降低音频噪声？ | |
| [答：henrylaw] | Higher PWM frequency to 20KHz, higher than audiable frequency. | [2007-6-27 11:07:48] |
| [问：yuyhbeijing2] | 閃光燈升壓電路可以長時間的連續工作嗎？ | |
| [答：henrylaw] | No, all our flash LED driver have time out protection. | [2007-6-27 11:08:57] |
| [问：xsj19810419] | 多路LED電流的匹配誤差主要有那些因素確定? | |
| [答：alanchang] | If parallel LED is used, current regulator is built in controller IC at low output voltage. So current regulator accuracy is an error source. But if you use multi-series then parallel LEDs (example: 8S6P), LM3432 is a good current regulator for current matching. In this case, how LED is put and wire route are another error source. Finally, your layout is important to keep away noise at FB signal. | [2007-6-27 11:12:19] |
| [问：sd2620] | LM2796的价格是多少？ | |
| [答：henrylaw] | Our 1K unit price is listed on our internet www.national.com | [2007-6-27 11:12:57] |
| [问：liqiyong] | 如何最有效解決DC-DC的效率問題? | |
| [答：samting] | For DC/DC converter efficiency concern, we have to choose the right topology first, then fine tune the exteral components to optimize the design. By the way, the PCB layout is important, too. | [2007-6-27 11:14:03] |
| [问：anfeng01] | 1.在设计给白光LED供电时，要保持各路发光一致，亮度一致，需要重点关注那些问题？ 2.要提高驱动电源的效率，主要应该从那些方面着手考虑？ 3.由于驱动是较高频率的信号，在EMI上面我们要考虑那些设计问题，Layout方面呢？ | |
| [答：rickzhong] | 1：串联的LED的亮度一致性是有保证的。而并联的LED的亮度一致性是有驱动芯片的输出电流的“Current matching"保证的。客户应该选择“current matching"特性比较好的驱动芯片； 2：驱动芯片的选择决定的电路的效率。芯片的datasheet中一般都提供芯片的效率信息； 3：电感式电路电压，频率都比较高，在emi方面应该更加注意。在NS 产品的DATASHEET中，都有相关的layout注意事项说明； | [2007-6-27 11:14:48] |
| [问：劉聚成] | 亮度控制的方法有四種，各自的優缺點，在具體的應用中怎樣選擇？ | |
| [答：henrylaw] | PWM is still the best for the whiteness of the LED as the current flow through the LED is in the best condition, but it has to be avoid audioable frequency, National Semiconductor is also using micro PWM controller through I2C control, it can also lower the interference and EMI; analog dimming is less noisy but just the whiteness of the LED is scarified! | [2007-6-27 11:15:55] |
| [问：Seal Lee] | NS的閃光燈電源能保證照相手機的連續拍照或者說是攝像嗎?升壓達到額定值的時間有多快? | |
| [答：rickzhong] | The turn on time of flash led diver is much faster than camera sensor. | [2007-6-27 11:17:34] |
| [问：sszzjj] | NS是如何靠程序补偿调整LED的差异性的？ | |
| [答：janetwu] | In the lighting management unit, we include I2C interface to allow easy control of the chip. | [2007-6-27 11:17:40] |
| [问：laoyi] | 请问：LM27965、LM27966支持的最大屏幕尺寸是？ | |
| [答：henrylaw] | Usually 3.5", but it depends how you arrange the layout of LED and disfuser. | [2007-6-27 11:20:13] |
| [问：sd2620] | 请问：贵公司的产品具有抗干扰能力吗？若用于一般的场合，是否还需要采取额外的抗干扰措施？ | |
| [答：robertshen] | 取决于干扰源。一般场合不必加入额外的抗干扰措施。 | [2007-6-27 11:20:15] |
| [问：qinchuren] | 请问如果手机使用闪光灯，瞬间会抽取很大电流>1A,这时候贵司产品是否有预防大电流拉底Vbat导致手机瞬间掉电的设计机制？？ 万一闪光灯瞬间恰巧是RF page网络时候，岂不更危险了？？ | |
| [答：rickzhong] | 我们的Flash led 驱动电路提供很多电流安全控制功能：如软启动，以及和RF PA 同步的功能，以保证系统的用电安全。 | [2007-6-27 11:20:25] |
| [问：Seal Lee] | LP5527是否採用了多個LDO?採用電感負載在佈局(Layout)時如何考慮? | |
| [答：alanchang] | LP5527 uses an inductive boost regulator for LED power. In all boost regulator, inductor, MOSFET and input,output capacitor are put together to reduce noise. All GND vias are put close to capacitor then go to inner GND layer. Compensation network and feedback are away from inductor. | [2007-6-27 11:21:40] |
| [问：翰斯倍麗] | 高功率LED驅動電路是否需要外接MOS器件或必須要用專用的驅動電路嗎？ | |
| [答：henrylaw] | Not necessary, LM3509 is a very high efficiency LED driver. | [2007-6-27 11:22:36] |
| [问：zxyryf37] | 你好: 请问你们的技术能否应用于普通的照明电路中呢? 谢谢 | |
| [答：robertshen] | 用LED可以用于普通的照明，节能、环保。我们的产品和技术可以用于这类应用。 | [2007-6-27 11:22:55] |
| [问：laoyi] | NS是否提供评价电路板以供测试？ | |
| [答：henrylaw] | Yes, please try with our webbench or contact our distributors or sales offices. | [2007-6-27 11:23:15] |
| [问：tonghua] | 採用Audio Syn後是否不會出現音頻噪音?爲什麽? | |
| [答：rickzhong] | The audio signal is input signal for LED driver, LED driver has very high input impendance, has no any impact on audio source. | [2007-6-27 11:23:15] |
| [问：yuyhbeijing2] | 閃光燈升壓電路是否可以用於其他DC-DC電路中？ | |
| [答：samting] | In flash app, the output only needs to discharge for a short time. However, the DC/DC converter can support a continuous output, such as LM2733, LM2731, LM27313.... | [2007-6-27 11:24:04] |
| [问：zirconsdu] | NS的电荷泵的效率有多高?请专家解释一下电荷泵升压原理 谢谢 | |
| [答：henrylaw] | Up to 93%. The multigain charge pump will switch to the optimized gain depends on the Vin and Vout situation. | [2007-6-27 11:24:15] |
| [问：jimlee0924] | LED驅動中怎樣使器件不受浪湧電流的衝擊？ | |
| [答：janetwu] | In the LED driver involves internal soft-start to limits Inrush Current | [2007-6-27 11:24:21] |
| [问：xing628] | 請介紹NS的電荷泵升壓電源的效率和升壓倍數.所需的升壓電容最低爲多少? | |
| [答：alanchang] | For Gain, NSC has -1, +1, 1.5,2 etc depending on different parts. Efficiency is difficult to say how much high, since it depends on conditions, but normally, 70~85%. Every part has boost cap. requirement. You can find them in data sheet. | [2007-6-27 11:25:06] |
| [问：sd2620] | 与其他厂家类似产品相比，贵方产品有什么特点？ | |
| [答：robertshen] | 集成度高，效率高，产品全，设计方便，技术支持强 | [2007-6-27 11:25:49] |
| [问：simao310] | NS目前的電源管理晶片能控制多少個顯示器?請舉些型號,並簡單介紹它們的性能.謝謝! | |
| [答：henrylaw] | FPD95120 is our flag ship product for LTPS driver with Mobile Pixel link interface to speed up the tranmissed time. | [2007-6-27 11:27:06] |
| [问：liqiyong] | 對LED的Time-out的保護時間是否可編程?不同的LED,它的Time-out保護時間是否會有所不同? | |
| [答：rickzhong] | Usually we put Timer-out feature in Flash led driver, because Flash needs very high current in short time. The timer is long enough for a reasonable Flash. | [2007-6-27 11:27:53] |
| [问：xsj19810419] | DC/DC設計中哪些指標比較難達成?NS的産品在哪些方面比較有優勢? | |
| [答：henrylaw] | Like higher efficiency with very small size inductor, like our LM3677 using 1uH inductor and can deliver over 90% efficiency. | [2007-6-27 11:28:09] |
| [问：zhm1977] | 什麽是軟開關技術?NS有這方面的産品嗎? | |
| [答：henrylaw] | Softstart is maintain a suitable ramp up rate to prevent over shot, most of NS newer products got this features like LM3677, LM3508. | [2007-6-27 11:29:46] |
| [问：woshijinmi] | LM27965和LM27966有什么区别？ | |
| [答：henrylaw] | LM27965 can driver more LEDs than LM27966. | [2007-6-27 11:30:05] |
| [问：楊順發] | dear all 1.燈火如何管理 2.如何省電 | |
| [答：samting] | For efficiency concern, we have to choose the right topology first, then fine tune the external components to optimize the design. By the way, the PCB layout is important, too. | [2007-6-27 11:30:27] |
| [问：Seal Lee] | 貴公司的DC-DC晶片的最小輸出電壓是多少？我想用0.6V的電壓，不知道有沒有這樣的晶片? | |
| [答：alanchang] | NSC has 0.6V output LDO, switcher and controller as shown below. LDO: LP38841-ADJ Switcher: LM2831/2/3 Controller: LM2743/4/5/8, LM2728, LM27241 | [2007-6-27 11:30:43] |
| [问：sd2620] | LM27966能用于无线局域网络吗？ | |
| [答：henrylaw] | Yes, if you need a LED display, or you want to drive the RF or core chips? | [2007-6-27 11:31:20] |
| [问：laoyi] | 背光亮度可以调节吗？如何实行此功能？ | |
| [答：janetwu] | Please refer to our RGB backlight LED driver LP5520 for instance. It can be used to control backlight intensity in white LED backlight applications. | [2007-6-27 11:31:38] |
| [问：woshijinmi] | 请问：LM27966最大驱动电流是多大？ | |
| [答：rickzhong] | LM27966 can drive 6 LED with up to 30mA per LED. | [2007-6-27 11:31:39] |
| [问：liqiyong] | 貴公司的DC/DC電源轉換器的紋波能夠做到多小？ | |
| [答：samting] | Under 10mV, depends on application and external components selection. | [2007-6-27 11:32:20] |
| [问：tonghua] | 如何避免DC/DC轉換器的暫態過載的出現?如何進行保護?有何措施? | |
| [答：davidshaw] | 1. In general DC/DC have over current limit protection, it is cycle by cycle limit. If you choose 3A (peak) is your set point, when the peak current over 3A, the output will shutdown. When the curent go down, the device will operate again. So just set the OCP CKT. | [2007-6-27 11:32:31] |
| [问：sszzjj] | 驱动芯片的功率主要由什么来决定的？ | |
| [答：rickzhong] | The outpur power is decided by LED current and forward voltage. | [2007-6-27 11:32:52] |
| [问：woshijinmi] | 在LM2796系列产品中，背光亮度如何调整？ | |
| [答：henrylaw] | It has current sources enables for PWM dimming. However it is a older part, please use LM27966. | [2007-6-27 11:35:17] |
| [问：劉聚成] | LED驅動如何有效的降低EMI？ | |
| [答：samting] | By proper PCB layout and using snubbers. | [2007-6-27 11:35:31] |
| [主持人：ChinaECNet] | 各位觀眾，現在用戶提問很踴躍，專家正在逐一回答。請耐心等待您問題的答案，同一問題請不要多次提交。 | [2007-6-27 11:35:44] |
| [问：zhm1977] | 開關電源的輸出波紋一般有點高,在後處理中有那些方法可得到滿意的波紋如小於1mV? | |
| [答：janetwu] | To reduce the output ripple, you can increase the value of the inductor above the minimum recommended value. Once the ripple current is less than 20% of the average current in the inductor, the benefit to output ripple becomes minimal. Also capacitor with low ESR and ESL help to control the ripple. | [2007-6-27 11:36:01] |
| [问：gumulaoyi] | 请问: LM27965和LM27966采用什么封装方式？ | |
| [答：henrylaw] | LLP 24 like QFN 4mm x 4mm. | [2007-6-27 11:36:38] |
| [问：woshijinmi] | LM27965最多可驱动几个并联的LED？ | |
| [答：henrylaw] | 9, but can be more if you use smaller current LED , like those for keypad lighting. | [2007-6-27 11:39:08] |
| [问：lulu2890] | 您好请问LM27965最优供电方式是锂离子电池供电吗？ | |
| [答：henrylaw] | Yes. | [2007-6-27 11:39:26] |
| [问：zxyryf37] | 你好, 请问这些新技术对于功耗是否有所改善呢? 谢谢 | |
| [答：janetwu] | Yes, definitely. | [2007-6-27 11:39:36] |
| [问：sszzjj] | 請問1% current matching是指什麼意思呢? | |
| [答：henrylaw] | Between any two LED, the current difference is less than 1%. | [2007-6-27 11:39:57] |
| [问：sszzjj] | 如何选择适合RGB背光的LED？ | |
| [答：henrylaw] | Look at the rise and fall time, and try with our LP5520 driver. | [2007-6-27 11:41:11] |
| [问：xcsunsz] | 贵方在河南有经销商吗？ | |
| [答：stellawong] | You can find our distributors" detailed information at S.Chinese version: www.national.com/CHS/contacts/ T.Chinese verions: www.national.com/CHT/contacts/ English version: www.national.com/contacts/ | [2007-6-27 11:41:24] |
| [问：xcsunsz] | 需要极高驱动效率的应用方案，那个型号最适用，请专家推荐一下。 | |
| [答：henrylaw] | LM3508, LM3509. | [2007-6-27 11:41:38] |
| [问：woshijinmi] | 请问贵方产品是否已经通过国际和国内相关认证和法规标准？ | |
| [答：robertshen] | 是的 | [2007-6-27 11:42:05] |
| [问：yuyhbeijing2] | NS的閃光燈電源能對多大的電容進行充電?充電速度有多快?那款産品的充電速度快? | |
| [答：rickzhong] | LM2754 is our latest switched cap based Flash LED driver. With high working frequency, LM2754 can support very small fly capacitor(2.2uF), which support very fast charging and discharging time. | [2007-6-27 11:42:50] |
| [问：gumulaoyi] | 电荷泵是什么意思？ | |
| [答：janetwu] | 电荷泵是电压转换的一种拓扑结构，英文名叫charge pump。您可以通过搜索得到详细的信息。谢谢。 | [2007-6-27 11:43:27] |
| [问：gumulaoyi] | 请问专家：哪里可以下载到详细技术参考资料？ | |
| [答：stellawong] | You can visit our website at www.national.com | [2007-6-27 11:43:53] |
| [问：laoyi] | 什么是恒流驱动器,和固定电压驱动器有什么不同？ | |
| [答：robertshen] | 是指电流恒定。固定电压是指电压恒定 | [2007-6-27 11:43:59] |
| [问：zzyjg] | LM2795中，Boost Voltage是固定的吗？ | |
| [答：henrylaw] | No, it depends on the input and Vf voltage of the LED. However, it is an old part, please use LM27951. | [2007-6-27 11:44:18] |
| [问：sd2620] | LM27965外形尺寸有多大？ | |
| [答：alanchang] | LM27965 is a LLP-24 package, 4x4x0.8 mm | [2007-6-27 11:46:44] |
| [问：zzyjg] | 白色LED驱动器在哪个领域应用最广泛？ | |
| [答：henrylaw] | Backlighting for LIQUID crystal display | [2007-6-27 11:47:20] |
| [问：xcsunsz] | 贵公司的技术支持电话是多少？ | |
| [答：stellawong] | If you need any technical support, you can send e-mail to us at ap.support@nsc.com or visit http://www.national.com/CHS/support/ and submit the online request form. | [2007-6-27 11:47:57] |
| [问：sszzjj] | LED的应用领域和发展前景是什么？ | |
| [答：robertshen] | 是照明的地方都可使用，发展前景非常广阔 | [2007-6-27 11:48:02] |
| [问：zzyjg] | LM27966发热量大吗？如何散热？ | |
| [答：janetwu] | LM27966 is in LLP package which is a leadframe based Chip Scale Package with very good thermal properties. The main advantage is to offer lower thermal resistance when it is soldered to the thermal land on the PCB. Please see its datasheet for detail information. Thanks. | [2007-6-27 11:48:32] |
| [问：zzyjg] | 能否实现此功能：在户外日光下，背光会自动调节。 | |
| [答：rickzhong] | Yes. Lots of our products support analog dimming control. Designer can connect output from lighting senor to LED driver"s dimming control pin. In this way, the brightness of LED can be adjusted by enviromental lighting. | [2007-6-27 11:49:12] |
| [问：sduboy] | 哪些領域的可攜式產品涉及到發光二極體的應用？ | |
| [答：samting] | Such as mobile phone, PDA, samrt phone, PMP.... The apps are backlight, funny light, flash, keypad lighting... | [2007-6-27 11:51:00] |
| [问：xcsunsz] | 有没有相关的网上设计、建模工具？ | |
| [答：rickzhong] | Yes, we have lighting design tools available in our website. Customer can find it in our home page. | [2007-6-27 11:51:34] |
| [问：hexcdan] | 我在使用的时候遇到问题，能直接与贵公司国外技术人员联系吗？ | |
| [答：stellawong] | You can send e-mail to us at ap.support@nsc.com or go to www.national.com/CHS/support/ | [2007-6-27 11:53:22] |
| [问：hexcdan] | 哪有相关的设计软件可供下载？ | |
| [答：robertshen] | 我们有网上设计工具： 电源：http://www.national.com/appinfo/power/webench.html LED: http://www.national.com/appinfo/power/webench.html | [2007-6-27 11:53:46] |
| [主持人：ChinaECNet] | 所有問題均已提交給美國國家半導體公司的專家。座談期間未回答的問題，美國國家半導體公司專家也會逐一回答，並在中電網上公佈，請大家注意收看。 | [2007-6-27 11:53:57] |
| [问：gumulaoyi] | 请教：LM27965的分辨率有哪几种？ | |
| [答：alanchang] | For LED brightness, there are 32 non-linear brightness steps, and 1% current matching at any two LEDs. | [2007-6-27 11:55:15] |
| [问：hexcdan] | LM27965LM27965能使用锂电池以外的其它电源吗？ | |
| [答：rickzhong] | The Vin range of LM27965 is 2.7V to 5.5V, as long as the power source is in this range, LM27965 can work without any problem. | [2007-6-27 11:55:44] |
| [主持人：ChinaECNet] | 由於時間關係，本次中電網“線上座談”馬上就要結束了。雖然各位聽眾（網友）已與美國國家半導體公司的專家討論了許多問題，但是還有許多提問沒有來得及進行交流。本次線上座談結束後，中電網將請美國國家半導體公司的專家繼續答復所有的來自各位聽眾（網友）的提問，然後整理上載到中電網網站上，以便大家查閱。 | [2007-6-27 11:57:04] |
| [主持人：ChinaECNet] | 在此，中電網特別感謝給予本次中電網線上座談巨大支持的美國國家半導體公司，特別感謝專門線上回答各位聽眾（網友）提問的美國國家半導體公司的各位專家們，特別感謝各位聽眾（網友）積極熱情的參與。 | [2007-6-27 12:01:13] |
| [主持人：ChinaECNet] | 祝大家事業有成、生活愉快！歡迎多提寶貴意見，歡迎關注中電網，下次再見。 | [2007-6-27 12:01:26] |
| 非在线问答： | ||
| [问：sd2620] | 请问：贵公司产品功耗如何？ | |
| [答：] | Our LED drivers have best efficiency in industry | |
| [问：gumulaoyi ] | 请教：白色LED应用前景如何？ | |
| [答：] | LED has been widely used in portable applications. | |
| [问：lijun0524 ] | 可攜式產品的燈光可以节能吗 | |
| [答：] | Our LED drivers have best efficiency in industry | |
| [问：zzyjg ] | 现在LM27967货源充足吗？ | |
| [答：] | drop this question because no this part number | |
| [问：xcsunsz ] | LM2795如何实现与输入电压联动？ | |
| [答：] | drop this question | |
| [问：xcsunsz ] | 请问专家：这些产品主要应用在哪些领域？ | |
| [答：] | Portable application with LCD display | |
| [问：laoyi ] | LM2796系列国内供货吗？ | |
| [答：] | Yes. | |
| [问：cyberhnxx ] | 贵方产品有断电保护措施吗？ | |
| [答：] | drop this question | |
| [问：cyberhnxx ] | 贵公司产品有有输入/输出电压监控功能吗？ | |
| [答：] | Yes. Our switched cap based LED driver can automatically adjust the gain setting based on inout output voltage to maintain best efficiency. | |
| [问：cyberhnxx ] | 请告知贵公司本地经销商的联系方式，谢谢！ | |
| [答：] | "You can visit our website at English: www.national.com/contacts S. Chinese: www.national.com/CHS/contacts T. Chiense: www.national.com/CHT/contacts" | |
| [问：cyberhnxx ] | 贵公司产品支持大屏幕手机吗？ | |
| [答：] | We have product can drive up to 10 LEDs for portable application. | |
| [问：hengdonghui ] | LED驅動電路採用哪種拓撲結構？ | |
| [答：] | There are two kinds of topology: series and parallel. | |
| [问：翰斯倍麗 ] | 目前LED驅動的優缺點以及其發展趨勢？ | |
| [答：] | "Advantage: - Few wires in/out of display Disadvantage: - Requires high voltage booster Future trend: - More integration for light sensor interface and low voltage digital interface" | |
| [问：jimlee0924 ] | LED驅動需要更先進的亮度控制，NS採用了哪些方式來實現？ | |
| [答：] | "NS advanced technology: - high frequency PWM brightness control to avoid audio band noise - Lighting fade in and fade out - High current matching < 1% for switched cap. LED driver - Integrated lighting solution - Synchronous boost - Advanced current safety control for flash LED driver" | |
美国国家半导体致力开发各种高能源效率的模拟及混合信号半导体产品。该公司的PowerWise®系列产品旨在降低系统功耗，延长电池寿命，以及减少散热需求。美国国家半导体总部位于美国加州圣塔克拉拉(Santa Clara)，截至2008年5月25日为止的2008年财政年度的营业额达18.9亿美元。欲查询美国国家半导体的公司资料及产品信息，欢迎浏览该公司的网页，网址：www.national.com。
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