AL9910/AL9910A/AL9910-5 通用高电压、高亮度 LED 驱动器 NEW PRODUCT 说明 管脚排布 AL9910/A高电压脉冲宽度调制 (PWM) LED驱动器控制器,为 离线高亮度LED灯提供高效率的解决方案,整流线性电压由 85VAC到高达277VAC。AL9910以最高300kHz的开关频率驱动 外部MOSFET,而开关频率由单一电阻来设定。AL9910拓扑 打造了流过多颗LED的恒定电流,带来恒定光线输出。输出电 流通过一个外部电阻进行编程,并最终由选定的外部MOSFET 来决定,因而可驱动多颗低电流LED及数颗高电流LED。 LED 的 亮 度 可 利 用 AL9910 的 LD 管 脚 做 线 性 调 光 , 或 通 过 PWM_D管脚进行PWM调光。PWM_D输入以0~100%的占空 比率工作,频率可达数 kHz。 AL9910能抵受高达500V的输入电压, 使它可以非常灵活面对 标准主线电压的瞬变。AL9910可以SO-8 和温度增强 SO-8EP 封装供货。 (Top View) CS 2 7 LD 6 VDD 5 PWM_D SO-8 (Top View) 8 ROSC VIN 1 CS 2 AL9910 7 LD 6 VDD 5 PWM_D GND 3 GATE 4 效率>90% 注: AL9910 GND 3 GATE 4 功能 通用整流85 到277VAC输入范围 输入电压高达500V 内部稳压器省掉启动电阻 o 7.5V MOSFET驱动 – AL9910 o 10V MOSFET驱动 – AL9910A 更严格电流感测容测:5% AL9910-5 驱动兼备高及低电流LED的LED灯具 以线性及PWM调光提供LED亮度控制 内部温度保护 (OTP) 采用“绿色”模塑合成材料的SO-8和SO-8EP封装 (无溴和锑 ) ,具有无铅涂料/ 符合RoHS (注1) 8 ROSC VIN 1 SO-8EP 应用 LED离线灯具 高电压直流-直流LED驱动器 标志和装饰LED照明 平板显示屏的背灯 通用恒定电源 1. EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) 。所有相关的 RoHS 豁免都适用。请访问我们的网页: http://www.diodes.com/products/lead_free.html. 典型应用电路 D1 VAC IN VDD C1 BR1 VIN L1 Q1 AL9910/A LD C3 GATE C2 PWM_D ROSC GND CS RSENSE ROSC AL9910/AL9910A/AL9910-5 文件编号: DS35103 Rev. 7 - 2 第 1 页 (共 16 页) www.diodes.com 2012 年 9 月 © Diodes Incorporated AL9910/AL9910A/AL9910-5 通用高电压、高亮度 LED 驱动器 管脚说明 NEW PRODUCT 管脚名称 SO-8 说明 SO-8EP VIN 1 1 输入电压 CS 2 2 检测LED灯串和外部MOSFET开关电流 GND 3 3 器件接地 Gate 4 4 驱动外部MOSFET开关的栅极 PWM_D 5 5 低频率PWM调光管脚 ,以及 Enable输入。内部 200kΩ下拉至GND VDD 6 6 内部稳压电源电压。 DAL9910和AL9910-5G为7.5V标识 AL9910A为10V标识 能够为外部电路供应高达1 mA 电流。当整流交流输入接近零交叉时,一个 充足的存储电容 会用来提供存储。 LD 7 7 线性调光输入。改变电流感测比较器的电流限制阈值,并更改平均 LED电流。 ROSC 8 8 振荡控制。连接这支管脚与地的电阻将设定PWM频率。 器件可通过将ROSC管脚连接到外 部MOSFET栅极与外部振荡电阻之间,切换至恒定关断时间 (PFM) 模式。 EP PAD N/A EP 外露焊垫 (底层)。 在封装之下直接连接到 GND。 功能性方块图 AL9910/AL9910A/AL9910-5 文件编号: DS35103 Rev. 7 - 2 第 2 页 (共 16 页) www.diodes.com 2012 年 9 月 © Diodes Incorporated AL9910/AL9910A/AL9910-5 通用高电压、高亮度 LED 驱动器 极限参数 (注 2) 符号 参数 单位 VIN(MAX) 最大输入电压, VIN, 到GND -0.5 to +520 V VCS 最大 CS输入管脚电压对GND -0.3 to +0.45 V VLD VPWM_D VGATE NEW PRODUCT 额定值 VDD(MAX) 最大LD 输入管脚电压对GND -0.3 to (VDD +0.3) V 最大PWM_D输入管脚电压对GND -0.3 to (VDD +0.3) V 最大GATE管脚电压对GND -0.3 to (VDD +0.3) V 12 V 最大VDD 管脚电压对GND 持续功率耗散 (TA = 25C) TJ SO-8 (在+25C以上,每度降低6.3mW) 630 mW SO-8EP (在+25C以上,每度降低22mW) 2200 mW 结温范围 +150 °C -65 to +150 °C 存储温度范围 TST ESD HBM 人体模型 ESD 保护(注 3) 1500 V ESD MM 机器模型 ESD 保护 (注 3) 300 V 注: 2. 超过以上列出的极限参数或会对器件造成永久损害。这些只是应力额定值,而在这些数据或其它超过这个规格说明的操作部分所刊载的条件下,并 不表示器件能够正常运作。若器件长时间暴露在极限参数,器件的可靠性将受到影响。 所有电压皆参考对地。电流为正输入特定的终端,并由该终端负输出。 3. 半导体器件对静电释放 (ESD) 敏感,并且可能因暴露在 ESD 下而受到损害。当处理和运送这些器作时应该进行适当的 ESD 防护。 建议工作条件 符号 VINDC TA VDD 参数 输入直流供应电压范围 环境温度范围 (注 4) 最小 最大 AL9910 AL9910-5 15.0 500 AL9910A 20.0 500 AL9910_S -40 +85 AL9910_SP -40 +105 AL9910 AL9910-5 加诸 VDD 管脚的最大建议电压 (注 5) V °C 10 AL9910A V 11 VEN(LO) 管脚 PWM_D 输入低电压 0 1 VEN(HI) 管脚 PWM_D 输入高电压 2.4 VDD 注: 单位 V 4. 最大环境温度范围受可允许功率耗散限制。外露焊垫 SO-8EP 凭藉其较低热阻抗,允许这些变数利用该封装来扩展可允许最大环境温度范围。 5. 若于隔离 LED 灯应用 AL9910,就必须使用一组辅助绕组。 AL9910/AL9910A/AL9910-5 文件编号: DS35103 Rev. 7 - 2 第 3 页 (共 16 页) www.diodes.com 2012 年 9 月 © Diodes Incorporated AL9910/AL9910A/AL9910-5 通用高电压、高亮度 LED 驱动器 电气特性 (除非另有说明,否则采用建议的工作环境- TA = 25°C) 除非另有说明,否则规格适用于 AL9910、 AL9910A 和 AL9910-5 符号 参数 关闭模式电源电流 NEW PRODUCT IINSD VDD IDD(ext) 条件 管脚 PWM_D 到 GND, VIN = VIN(MIN) (注 6) 典型 最大 AL9910 AL9910-5 0.50 1 AL9910A 0.65 1.2 AL9910 AL9910-5 7.0 7.5 8.0 AL9910A 9.5 10 10.5 内部稳压 VIN = VIN(MIN)~500V, (注 6) lDD(ext) = 0, Gate 管脚开路 供外部电路使用的 VDD 电流 VIN = VIN(Min) 到 100V (注 6 及 7) 在电压闭锁阈值下的 VDD VDD 上升 UVLO 在电压闭锁滞回下的 VDD ∆UVLO VDD 下降 RPWM_D PWM_D 下拉电阻 VCS(HI) 最小 电流感测阈值电压 AL9910 AL9910-5 6.4 6.7 7 AL9910A 8.4 9 9.6 AL9910 AL9910-5 500 AL9910A 750 VPWM_D = 5V 全环境温度范围 (注 8) 1.0 单位 mA V mA V mV 150 200 250 AL9910 AL9910A 225 250 275 AL9910-5 237.5 250 262.5 kΩ mV VGATE(HI) GATE 高输出电压 IOUT = 10mA VDD -0.3 VDD V VGATE(LO) GATE 低输出电压 IOUT = -10mA 0 0.3 V ROSC = 1MΩ 20 25 30 ROSC = 226kΩ 80 100 120 fOSC 震荡频率 DMAXhf 最大震荡 PWM 占空比 fPWMhf = 25kHz, 于 GATE, CS 到 GND。 线性调光管脚电压范围 全环境温度范围 (注 8), VIN = 20V tBLANK 电流感测消隐间隔 VCS = 0.45V, VLD = VDD tDELAY 由 CS trip 到 GATE lo 的延迟 VLD 注: kHz 100 % 0 - 250 mV 160 250 440 ns 300 ns VIN = 20V, VLD = 0.15, VCS = 0 到 0.22V,在 TBLANK 之后 tRISE GATE 输出上升时间 CGATE = 500pF 30 50 ns tFALL GATE 输出下降时间 CGATE = 500pF 30 50 ns TSD 温度关闭 150 TSDH 温度关闭滞回 50 JA 结至环境热阻 JC 结至外壳热阻 6. 7. 8. 9. 10. SO-8 (注 9) 110 SO-8EP (注 10) 66 SO-8 (注 9) 22 SO-8EP (注 10) 9 C C/W C/W AL9910 的 VIN(MIN)为 15V,AL9910A 的就为 20V。 同时受制予封装功率耗散界限,视乎哪个较低。 AL9910-5S、AL9910AS 和 AL9910S 的全环境温度范围为 -40 到+85°C;AL9910-5SP、AL9910ASP 与 AL9910SP 的则为 -40 到+105°C。 器件贴装在 FR-4 PCB (25 毫米 x 25 毫米 1 安士铜,最小建议焊热布局在上层。为达到较好热性能,散热器必须使用较大的铜垫。 器件贴装在 FR-4 PCB (51 毫米 x 51 毫米 2 安士铜,最小建议焊热布局在上层,热力穿过到底层地平面。为达到较好热性能,散热器必须使用较大 的铜垫。 AL9910/AL9910A/AL9910-5 文件编号: DS35103 Rev. 7 - 2 第 4 页 (共 16 页) www.diodes.com 2012 年 9 月 © Diodes Incorporated AL9910/AL9910A/AL9910-5 通用高电压、高亮度 LED 驱动器 460 2.5 440 2.0 420 INPUT CURRENT (µA) CURRENT SENSE THRESHOLD (mV) 3.0 1.5 1.0 0.5 0.0 V IN = 400V 400 V IN = 15V 380 360 340 -0.5 320 -1.0 300 -1.5 -40 280 -40 -15 10 35 60 85 AMBIENT TEMPERATURE (°C) Change in Current Sense Threshold vs. Ambient Temperature 85 Input Current vs. Ambient Temperature SHORT CIR CUIT OU TPUT CURRENT (mA) 1.0 CHANGE IN FREQUENCY (%) -15 10 35 60 AMBIENT TEMPERATURE (° C) 450 1.5 0.5 R OSC = 226k 0.0 -0.5 ROSC = 1M -1.0 -1.5 -2.0 -40 -15 10 35 60 85 AMBIENT TEMPERATURE (°C) Change in Oscillation Frequency vs. Ambient Temperature ILED(NOM) = 180mA 400 350 300 250 200 150 85 105 125 145 165 185 205 225 245 265 INPUT VOLTAGE (VRMS ) 180mA LED Driver Short Circuit Output Current vs. Input Voltage 100 ILED = 281mA 90 V IN = 264V TA = 23.5C 80 70 IOUT MAX (%) NEW PRODUCT 典型特性 60 50 40 30 20 10 0 0 100 150 200 250 V LD DIMMING CONTROL (mV) I OUT MAX vs. V LD Dimming Control 50 AL9910/AL9910A/AL9910-5 文件编号: DS35103 Rev. 7 - 2 300 第 5 页 (共 16 页) www.diodes.com 2012 年 9 月 © Diodes Incorporated AL9910/AL9910A/AL9910-5 通用高电压、高亮度 LED 驱动器 典型特性(續) ──使用 AL9910EV4 时进行测量 200 95 15 LEDs 14 LEDs 190 18 LEDs EFFICIENCY (%) IOUT MAX (mA) 16 LEDs 170 17 LEDs 160 90 17 LEDs 14 LEDs 16 LEDs 85 15 LEDs 150 18 LEDs 140 85 80 85 105 125 145 165 185 205 225 245 265 INPUT VOLTAGE (VRMS ) 180mA LED Driver Output Current vs. Input Voltage 0.95 105 125 145 165 185 205 225 245 265 INPUT VOLTAGE (VRMS ) 180mA LED Driver Efficiency vs. Input Voltage 12 17 LEDs 18 LEDs 18 LEDs 0.9 POWER (W) 10 POWER FACTOR NEW PRODUCT 180 16 LEDs 0.85 17 LEDs 0.8 16 LEDs 8 15 LEDs 14 LEDs 15 LEDs 6 0.75 14 LEDs 0.7 85 105 125 145 165 185 205 225 245 265 INPUT VOLTAGE (VRMS ) 180mA LED Driver Power Factor vs. Input Voltage AL9910/AL9910A/AL9910-5 文件编号: DS35103 Rev. 7 - 2 4 85 105 125 145 165 185 205 225 245 265 INPUT VOLTAGE (VRMS ) 180mA LED Driver Input Power Dissipation vs. Input Voltage 第 6 页 (共 16 页) www.diodes.com 2012 年 9 月 © Diodes Incorporated AL9910/AL9910A/AL9910-5 通用高电压、高亮度 LED 驱动器 应用信息 AL9910非常灵活,能够在隔离或非隔离拓朴中工作。它亦可以在持续或非持续导通模式下工作。 VIN VIN 7.5/10V LDO OSC VDD VDD 250mV NEW PRODUCT ROSC S R LD O GATE CS OTP PWM_D 100k AL9910/AL9910A RSENSE GND 图. 1 基础方块图 AL9910包含了一个高电压LDO (参见图1) 。该LDO的输出为包括栅极驱动器在內的内部电路提供導电轨。于LDO输出的 UVLO 防止在VIN 管脚的低输出电压下出现错误工作。 在非隔离降压LED驱动器中,当栅极管脚变为高电平,外部功率MOSFET Q1便会启动,使电流流过LED、电感器 (L1) 和电流 感测电阻 (RSENSE) 。如RSENSE的电压超过电流感测管脚阈值,外部MOSFET Q1就会关闭。存储在电感器里的电力将使电流 继续通过二极管D1流过LED。 AL9910的LDO为IC的其它部分提供全部功率,包括栅极驱动,所以不需要大型高功率启动电阻。这表示系统需要由高电压导电 轨提供大约0.5mA,方能正常工作。LDO也可以同时用来为外部电路供应高达1mA的电流。 AL9910通过限制外部MOSFET的尖峰电流来工作和调节。尖峰电流感测阈值一般设定为250mV。 相同的基本工作也适用于隔离式拓朴,只是在这种情况下,变压器存储的电力可于外部MOSFET处予关断周期时为LED提供能 源。 设计参数 设定LED电流 在非隔离降压转换器拓朴 (图1) ,平均LED电压并不等如把尖峰电流除以2。然而,电感器内尖峰电流与平电流之间的差异导致 一定的误差。下列方程式便说明了这个误差: 250mV R SENSE . ILED (0.5 * IRIPPLE )) AL9910/AL9910A/AL9910-5 文件编号: DS35103 Rev. 7 - 2 第 7 页 (共 16 页) www.diodes.com 2012 年 9 月 © Diodes Incorporated AL9910/AL9910A/AL9910-5 通用高电压、高亮度 LED 驱动器 应用信息(续) 设定工作频率 NEW PRODUCT AL9910能够于25~300kHz的频率范围内操作。开关频率可通过连接ROSC 管脚与地的外部电阻来进行编程。相关的震荡周期 是: 22 R tOSC = osc µs ROSC 以 k計算 25 开关频率为震荡周期的倒数。ROSC 的典型值可由 75k 到 1M 不等。 若要驱动较少数量的 LED,就必须小心确保 tON > tBLANK。最简单的方法莫如通过提高 ROSC 值来降低/限制开关频率。减少开 关频率亦能改善效率。 应用以降压模式操作时,设计师应紧记输入电压必须保持高于跨越LED的正向电压降的2倍。当AL9910以大于0.5的占空比运 作,输出电流便可能出现不稳定性,而上述限制则与这种不稳定性相关。该不稳定性将由处予开关频率的次谐波 (SBO) 的输 出电流震荡反映出来。 最好的解决方案就是采用所谓的恒定关断时间操作 (如图2) 。电阻 (ROSC) 既定为接地,以设定工作频率。为了迫使AL9910进 入恒定关断时间模式,ROSC与外部MOSFET的栅极连接。这将通过增加以tOFF + tON计算的总周期,从50%进一步减少占空 比。 VIN VDD LD VIN Q1 AL9910/A GATE PWM_D ROSC GND CS ROSC 图. 2 恒定关断时间配置 以上的震荡周期方程式现在决 定 AL9910 的关断时间 tOFF。 若使用这个模式,标识开关频率便已选定,所以关断时间也可凭藉标识输入和输出电压计算出来: VOUT(nom ) 1 t OFF 1 fOSC V IN ( nom ) 利用这个计时电阻可以计算出 ROSC: R OSC t OFF (µs) 25 22(k) AL9910/AL9910A/AL9910-5 文件编号: DS35103 Rev. 7 - 2 第 8 页 (共 16 页) www.diodes.com 2012 年 9 月 © Diodes Incorporated AL9910/AL9910A/AL9910-5 通用高电压、高亮度 LED 驱动器 应用信息 (续) 电感器选择 NEW PRODUCT 应用通常选用如图1所示的非融离式降压电路。它有2个操作模式:持续和非持续导通模式。降压功率级可将于负载电流超过某 个水平时 (通常为全负载的15%~30%) ,以持续模式运作为设计目标。一般来说,输入电压范围、输出电压和负载电流,都取 决于功率级的规格。这使电感值成为唯一用来维持持续导通模式的设计参数。下列的示例显示如何计算维持持续导通模式所需 的电感器最少值。 所需的电感值取决于电感器中理想的尖峰-尖峰LED纹波电流,通常约为标称LED电流的30%。 VIN VLEDs D 當中的D為占空比 L= 0.3 ILED fOSC 下一步便是决定于LED灯串两端的总电压降。例如,若灯串由10颗高亮度LED灯组成,同时每颗二极管在标识电流下的正向电 压降为3.0V,总LED电压VLEDS就会是30V。 调光 LED的亮度可以视乎应用,采用线性 (利用LD管脚) 、脉冲宽度调制 (使用PWM-D管脚) ,又或者是两者结合的方式来进行调 节。把PWM_D管脚连接到地将关闭AL9910。当AL9910被停用时,其静态电流一般为0.5mA (如是AL9910A,则为0.65mA)。 降低 LD电压将减少LED电流,但由于的有限消隐周期的关系,并不会完全关闭外部功率晶体管和LED电流。只有PWM_D管脚 可关闭功晶体管。 线性调光可通过为LD管脚提供一个45~250mV的模拟信号来完成。这将盖过CS管脚的缺省250mV阈值并减少输出电流。如果 提供给LD的输入电压超过250mV,输出电压就不会改变。 LD管脚也可以为软启动提供一个经济的解决方案。通过于LD管脚初始上电时利用一颗电容器将 LD管脚连接到地,LD管脚便会 维持在低水平,使感测阈值也偏低。随着电容器上电,电流感测阈值将提高,结果导致平均 LED电流增加。 PWM调光是通过给予PWM_D管脚一个外部PWM信号来实现。LED电流与PWM占空比成正比,同时光输出可在0与100%之间 进行调节。该PWM信号会启动和关闭AL9910,从而调制LED电流。调光的最终精度只受制予最小栅极脉冲宽度,也就是低频 率占空比的极少部分。LED灯的PWM调光,则可通过利用低频50Hz~1000Hz TTL逻辑水平信号开启或关闭转换器来完成。 采用这两种调光模式都无法使平均亮度高于由AL9910的电流感测阈值所设定的水平。若应用需要较大的LED电流,就应该采用 一颗较小的感测电阻。 输入开路保护 因为 LED 与电感器以串联方法连接在一起,所以非隔离降压 LED 驱动器拓朴能够提供针对 LED 灯串中的开路状况的固有保护 功能。如 LED 灯串变为开路,开关就不会发生,电路继而永远维持在这个状态,且对电路其它部分造成损害。 AL9910/AL9910A/AL9910-5 文件编号: DS35103 Rev. 7 - 2 第 9 页 (共 16 页) www.diodes.com 2012 年 9 月 © Diodes Incorporated AL9910/AL9910A/AL9910-5 通用高电压、高亮度 LED 驱动器 应用信息 (续) 交流/直流离线LED驱动器 AL9910是经济的离线降压LED驱动器控制器,特别为驱动LED灯串而设计。它适合于整流交流线或任何介乎15~500V之间的直 流电压中操作。参看图3 的典型电路。 LED + NEW PRODUCT D1 VAC IN VDD C1 BR1 C2 LD VIN C3 L1 LED - AL9910/A Q1 GATE PWM_D ROSC GND CS RSENSE ROSC 图. 3 典型应用电路 (无 PFC) 降压设计方程式: D VLEDs VIN t ON L D fosc ( VIN VLEDs ) t ON 0.3 ILED R SENSE 0.25 当中 ILED x 0.3 = IRIPPLE ILED (0.5 (ILED 0.3)) 设计示例 若交流线电压为120V,标称整流输入电压 VIN = 120V*1.41 = 169V。凭此及LED串电压,就可以决定占空比: D = VLEDs /VIN = 30/169 = 0.177 所需的外部MOSFET 导通时间可利用开关频率来计算,例如当fOSC = 50kHz: tON = D/fOSC = 3.5 µs 如果LED电流为350mA,相关电感值就会如下: L = (VIN - VLEDs) * tON /(0.3 * ILED) = 4.6mH AL9910/AL9910A/AL9910-5 文件编号: DS35103 Rev. 7 - 2 第 10 页 (共 16 页) www.diodes.com 2012 年 9 月 © Diodes Incorporated AL9910/AL9910A/AL9910-5 通用高电压、高亮度 LED 驱动器 应用信息(续) 输入储能电容 离线灯需要一个输入储能电容去确保整流交流电压于整个交流线周期中,都保持于LED串电压的2倍。 CIN PIN (1 D CH ) 2 VLINE _ MIN 2fL VDC _ MAX NEW PRODUCT 其中 Dch : Capacity charge work period,一般大約為 0.2~0.25 fL :全范围的输入频率 (85~265VRMS) VDC _ MAX 应该设定为 2 VLINE _ MIN 的10~15% 若电容器拥有一道15%的电压纹波,以下这条简化方程式便可用来大约计算储能输入电容器的最低值: I VLEDs 0.06 CMIN = LED VIN2 功率参数校正 如功率参数需要改善,同时输入功率低于25W,便可以把一个简单的无源功率参数校正电路加到典型的AL9910应用电路。图4 展示了无源 PFC电路 (3颗电流控制二极管和2颗相同的电容器) 没有对电路其余部分造成显著影响。简单的无源PFC改善了线 电流谐波失真,更达到高于0.85的功率参数。 Passive PFC LED + C4 C1 D1 VAC IN VDD BR1 LD C2 C3 VIN AL9910/A PWM_D ROSC GND Q1 LED L1 GATE CS RSENSE ROSC 图. 4 配备无源 PFC 典型应用电路 这2颗相同的电容器每一颗都必须额定为输入电压的一半,且拥有相等于从欠缺无源PFC之降压转换电路计算所得的CMIN 的2倍 电容量(参阅先前关于储能电容器计算的章节)。 欲知更多设计信息,请访问Diodes的网站,查看AN75。 AL9910/AL9910A/AL9910-5 文件编号: DS35103 Rev. 7 - 2 第 11 页 (共 16 页) www.diodes.com 2012 年 9 月 © Diodes Incorporated AL9910/AL9910A/AL9910-5 通用高电压、高亮度 LED 驱动器 应用信息(续) 直流-直流降压LED驱动器 于前一个章节所展示的交流输入降压 LED 驱动器设计程序,同样适用于直流输入 LED 驱动器。 当驱动 LED 长串时,必须注意不要引起 SBO,也就是最高 LED 串的电压应该减少 VIN 的一半。因此最大占空比必须保持低于 50%,或使用恒定关断时间以消除问题。 NEW PRODUCT 直流-直流升压LED驱动器 基于 AL9910 LED 驱动器控制的拓朴,器件可用于升压配置,只是精度会下调。相关设计只要利用运算放大器来测量 LED 电 流,并且以该运算放大器的输出去驱动 LD 管脚,便可改善精度。 假如LED灯串的正向电压降高于输入电源电压,就须采用一个升压LED驱动器。比方说,若输入电压由一个48V电源供电,而 且相关的LED灯串由20伙HB LED灯组成 (可见于街灯),升压拓朴便会适用。 L1 VDD C1 VIN VIN D1 Q1 AL9910/A PWM_D GATE C2 LD ROSC CS C3 GND ROSC RSENSE 图. 5 升压LED驱动器 在升压转换器中,外部MOSFET导通之后,电力便会存储于电感器,然后当该外部MOSFET关闭,电力则全供应至输出。如存 储在电感器中的电力并没有在下一个开关周期前完全耗尽 (持续导通模式) ,输入与输出电压之间的直流转换由下列方程式决 定: V VIN V VOUT IN D OUT VOUT 1 D MOSFET的导通时间可用开关频率 fOSC和下列方程式计算; D t ON fOSC 再进而决定所需电感值: V t L IN ON 0.3 ILED 升压拓朴LED驱动器需要一枚输出电容,在外部MOSFET导通时供应电流予LED串。 在升压LED驱动器拓朴内,如果 LED须要开路,便可能对功率开关造成损害,所以器件要备有侦测功能以提供过压侦测或保 护。 AL9910/AL9910A/AL9910-5 文件编号: DS35103 Rev. 7 - 2 第 12 页 (共 16 页) www.diodes.com 2012 年 9 月 © Diodes Incorporated AL9910/AL9910A/AL9910-5 通用高电压、高亮度 LED 驱动器 订购信息 AL9910 X XX XX - 13 Variant NEW PRODUCT Blank : 7.5V VDD A : 10V VDD 器件 AL9910-5S-13 AL9910-5SP-13 AL9910AS-13 AL9910ASP-13 AL9910S-13 AL9910SP-13 注: VCS Tolerance Blank : 10% -5 : 5% Package Packing S : SO-8 SP : SO-8EP VCS 容差 封装编码 封装 (注 10) ±5% ±5% ±10% ±10% ±10% ±10% S SP S SP S SP SO-8 SO-8EP SO-8 SO-8EP SO-8 SO-8EP 13 : 13” Tape & Reel 数量 2500/卷带 2500/卷带 2500/卷带 2500/卷带 2500/卷带 2500/卷带 13 寸卷带 封装编码后缀 -13 -13 -13 -13 -13 -13 10. 焊垫布局如 Diodes 公司的建议焊垫布局文件 AP02001,该文件刊载于我们的网站 http://www.diodes.com/datasheets/ap02001.pdf . 标识信息 (1) SO-8 (2) SO-8EP AL9910/AL9910A/AL9910-5 文件编号: DS35103 Rev. 7 - 2 第 13 页 (共 16 页) www.diodes.com 2012 年 9 月 © Diodes Incorporated AL9910/AL9910A/AL9910-5 通用高电压、高亮度 LED 驱动器 封装外型尺寸 (所有尺寸以毫米展示) 0.254 (1) 封装类别: SO-8 NEW PRODUCT E1 E Gauge Plane Seating Plane A1 L Detail ‘A’ 7°~9° h 45° Detail ‘A’ A2 A A3 SO-8 尺寸 最小 最大 A 1.75 A1 0.10 0.20 A2 1.30 1.50 A3 0.15 0.25 b 0.3 0.5 D 4.85 4.95 E 5.90 6.10 E1 3.85 3.95 e 1.27 Typ h 0.35 L 0.62 0.82 0 8 所有尺寸以毫米展示 b e D (2) 封装类别: SO-8EP Exposed Pad 8 5 E1 1 H 4 F b Bottom View E 9° (All sides) N 7° A e D A1 AL9910/AL9910A/AL9910-5 文件编号: DS35103 Rev. 7 - 2 45° Q C 4° ± 3° Gauge Plane Seating Plane E0 SO-8EP (SOP-8L-EP) 尺寸 最小 最大 典型 A 1.40 1.50 1.45 A1 0.00 0.13 b 0.30 0.50 0.40 C 0.15 0.25 0.20 D 4.85 4.95 4.90 E 3.80 3.90 3.85 E0 3.85 3.95 3.90 E1 5.90 6.10 6.00 e 1.27 F 2.75 3.35 3.05 H 2.11 2.71 2.41 L 0.62 0.82 0.72 N 0.35 Q 0.60 0.70 0.65 所有尺寸以毫米展示 L 第 14 页 (共 16 页) www.diodes.com 2012 年 9 月 © Diodes Incorporated AL9910/AL9910A/AL9910-5 通用高电压、高亮度 LED 驱动器 建议焊垫布局 (1) 封装类别: SO-8 NEW PRODUCT X C1 C2 尺寸 X Y C1 C2 数值 (毫米) 0.60 1.55 5.4 1.27 尺寸 X Y X1 Y1 C1 C2 数值 (毫米) 0.60 1.55 3.30 2.66 5.4 1.27 Y (2) 封装类别: SO-8EP X Exposed Pad X1 C1 Y1 Y C2 AL9910/AL9910A/AL9910-5 文件编号: DS35103 Rev. 7 - 2 第 15 页 (共 16 页) www.diodes.com 2012 年 9 月 © Diodes Incorporated AL9910/AL9910A/AL9910-5 通用高电压、高亮度 LED 驱动器 注意事项 美商達爾科技股份有限公司 (Diodes Incorporated)不对本文件做任何明确或隐含的保证,包括但不限于针对特定用途的适销性和适用性的隐 含保证 (及任何管辖法律下的等同事项) 。 NEW PRODUCT 美商達爾科技股份有限公司及其附属公司保留权利,对本文件及在此处描述的任何产品进行修改、完善、改进、修正或其他更改,恕不另行通 知。美商達爾科技股份有限公司不承担任何由应用或使用本文件或本文所描述的任何产品所引致的责任;美商達爾科技股份有限公司没有传达 任何其专利权或商标专用权和其它人的权利。任何客户,或本文件及其所述产品的用户必须承担这些应用中的所有使用风险,并同意使美商達 爾科技股份有限公司及所有其产品刊载于美商達爾科技股份有限公司网站的其它公司免于承担所有补偿金的责任。 美商達爾科技股份有限公司不会对任何通过未经授权的销售渠道购买的产品作出保证或承担任何责任。 如果客户购买或使用美商達爾科技股份有限公司产品,作为任何非设定的或未经授权的应用,而这些非设定的或未经权的应用造成人身伤害或 死亡,并直接或间接引致的索偿行动,客户必须使美商達爾科技股份有限公司及其代表免于承担当中的所有索偿、补偿金、支出和律师费 。 本文件所述产品可能由一个或多个正在申请中的美国、国际或外国专利所涵盖。文中提到的产品名称和标记,也可能由一个或多个美国,国际 或外国商标所涵盖。 本文件的中文版本仅供参考,只有本文件的英文版本是美商達爾科技股份有限公司发布的最终和决定性的格式。 生命维持 除非美商達爾科技股份有限公司首席执行官发出书面许可,否则美商達爾科技股份有限公司的产品明确不获允许用作生命维持设备或系统的关 键器件。这里所指的包括: A. 生命维持设备或系统是: 1.为植入体内而设,或 2.用来维持或支撑生命;并且若在按照标签提供的使用指示的正确使用情况下出现故障,可合理地预期将对用户构成显着伤害。 B. 关键器件是指生命维持设备或系统内的任何器件,若其出现故障,可合理地预期会导致生命维持设备故障,或影响设备的安全或能效。 客户表示对其生命维持设备或系统,拥有一切与安全及法规分支相关的必备专门知识;并且承认及同意就其产品或任何在这些安全关键的生命 维持设备或系统中使用之美商達爾科技股份有限公司产品,全权负责所有法律、监管及与安全相关的要求,不论由美商達爾科技股份有限公司 提供的与设备或系统相关的信息或支持。再者,若在这些安全关键的生命维持设备或系统使用美商達爾科技股份有限公司产品而导致任何赔偿 金,客户须全数赔偿美商達爾科技股份有限公司及其代表。 © 2012 美商達爾科技股份有限公司。版权所有。 www.diodes.com AL9910/AL9910A/AL9910-5 文件编号: DS35103 Rev. 7 - 2 第 16 页 (共 16 页) www.diodes.com 2012 年 9 月 © Diodes Incorporated AL9910/ AL9910A/ AL9910-5 UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED DRIVER Description Pin Assignments (Top View) The AL9910/A high voltage PWM LED driver-controller provides an efficient solution for offline high brightness LED lamps from rectified line voltages ranging from 85VAC up to 277VAC. The AL9910 drives 8 ROSC VIN 1 CS 2 GND 3 external MOSFETs at switching frequencies up to 300kHz, with the switching frequency determined by a single resistor. The AL9910 topology creates a constant current through the LEDs providing AL9910 GATE 4 constant light output. The output current is programmed by one external resistor and is ultimately determined by the external 7 LD 6 VDD 5 PWM_D SO-8 MOSFET chosen and therefore allows many low current LEDs to be driven as well as a few high current LEDs. (Top View) The LED brightness can be varied by both Linear and PWM dimming 8 ROSC VIN 1 using the AL9910’s LD and PWM_D pins respectively. The PWM_D CS 2 GND 3 GATE 4 input operates with duty ratio of 0-100% and frequency of up to several kHz. The AL9910 can withstand input voltages up to 500V which makes it AL9910 7 LD 6 VDD 5 PWM_D very resilient to transients at standard mains voltages. As well as SO-8EP standard SO-8 package the AL9910 is available in the thermally enhanced SO-8EP package. Applications Features • • >90% Efficiency Universal Rectified 85 to 277VAC Input Range • Input Voltage Up to 500V • Internal Voltage Regulator Removes Start-Up Resistor 7.5V MOSFET drive – AL9910 10V MOSFET drive – AL9910A • Tighter current sense tolerance: 5% AL9910-5 • Drives LED Lamps with Both High and Low Current LEDs • LED Brightness Control with Linear and PWM Dimming • Internal Thermal Protection (OTP) • Available in SO-8 and SO-8EP Packages • Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2) • Halogen and Antimony Free. “Green” Device (Note 3) Notes: • LED Offline Lamps • High Voltage DC-DC LED Driver • Signage and Decorative LED Lighting • Back Lighting of Flat Panel Displays • General Purpose Constant Current Source 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant. 2. See http://www.diodes.com for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green" and Lead-free. 3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and <1000ppm antimony compounds. AL9910/ AL9910A/ AL9910-5 Document number: DS35103 Rev. 8 - 2 1 of 15 www.diodes.com December 2012 © Diodes Incorporated AL9910/ AL9910A/ A A AL9910-5 Typical Ap pplications s Circuit D1 VAC IN N VDD C1 BR1 VIN L1 Q1 AL99 910/A LD C3 GATE C2 PWM_D ROSC ND GN CS RSENSE ROSC Pin Descriiptions Pin Name Pin Numberr SO-8 SO-8 8EP Function VIN CS GND Gate PWM_D 1 1 age Input Volta 2 3 4 5 2 3 4 5 VDD 6 6 LD 7 7 ROSC 8 8 EP PAD N/A EP Senses LE ED string and exxternal MOSFET switch current Device Grround Drives the e gate of the exte ernal MOSFET switch. Low Frequ uency PWM Dim mming pin, also Enable E input. Inte ernal 200kΩ pull-down to GND. Internally regulated supplyy voltage. 7.5V nominal for AL9910 and AL L9910-5 10V nominal forr AL9910A. Can supply up to 1 mA forr external circuitrry. A sufficient sto orage capacitor is i used to provide storage when the rectifie ed AC input is ne ear the zero crosssing. Linear Dim mming Input. Cha anges the curren nt limit threshold at current sense e comparator and d changes the average LED L current. Oscillator Control. A resisttor connected be etween this pin and ground sets the PWM frequen ncy. The devicess can be sw witched into constant off time (PFM) mode by connecting the exterrnal oscillator ressistor between ROSC pin and a the gate of the t external MOS SFET. Exposed Pad P (bottom). Connect C to GND directly d undernea ath the package. Functiona al Block Dia agram AL9910/ AL9 9910A/ AL9910-5 Document numberr: DS35103 Rev. 8 - 2 2 of 15 www.diodes.com w December 2012 2 © Diodes Incorporate ed AL9910/ AL9910A/ AL9910-5 Absolute Maximum Ratings (Note 4) (@TA = +25°C, unless otherwise specified.) Symbol VIN(MAX) Parameter Maximum input voltage, VIN, to GND Ratings Unit -0.5 to +520 V VCS Maximum CS input pin voltage relative to GND -0.3 to +0.45 V VLD Maximum LD input pin voltage relative to GND -0.3 to (VDD +0.3) V Maximum PWM_D input pin voltage relative to GND -0.3 to (VDD +0.3) V Maximum GATE pin voltage relative to GND -0.3 to (VDD +0.3) V 12 V VPWM_D VGATE VDD(MAX) Maximum VDD pin voltage relative to GND Continuous Power Dissipation (TA = +25°C) SO-8 (derate 6.3mW/°C above +25°C) SO-8EP (derate at 22mW/°C above 25°C) 630 mW 2200 mW TJ Junction Temperature Range +150 °C TST ESD HBM ESD MM Storage Temperature Range -65 to +150 °C 1500 300 V V Notes: Human Body Model ESD Protection (Note 5) Machine Model ESD Protection (Note 5) 4. Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those listed in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. All voltages are with respect to Ground. Currents are positive into, negative out of the specified terminal. 5. Semiconductor devices are ESD sensitive and may be damaged by exposure to ESD events. Suitable ESD precautions should be taken when handling and transporting these devices Recommended Operating Conditions (@TA = +25°C, unless otherwise specified.) Symbol VINDC TA VDD Parameter Input DC Supply Voltage Range Ambient Temperature Range (Note 6) Maximum Recommended Voltage Applied to VDD Pin (Note 7) AL9910 AL9910-5 AL9910A AL9910_S AL9910_SP AL9910 AL9910-5 AL9910A Min Max 15.0 500 20.0 -40 -40 500 +85 +105 10 9.5 11 VEN(LO) Pin PWM_D Input Low Voltage 0 1 VEN(HI) Pin PWM_D Input High Voltage 2.4 VDD Notes: Unit V °C V V 6. Maximum ambient temperature range is limited by allowable power dissipation. The Exposed pad SO-8EP with its lower thermal impedance allows the variants using this package to extend the allowable maximum ambient temperature range. 7. When using the AL9910 in isolated LED lamps an auxiliary winding might be used. AL9910/ AL9910A/ AL9910-5 Document number: DS35103 Rev. 8 - 2 3 of 15 www.diodes.com December 2012 © Diodes Incorporated AL9910/ AL9910A/ AL9910-5 Electrical Characteristics (@TA = +25°C, unless otherwise specified.) Symbol Parameter Shut-Down Mode Supply Current IINSD Internally Regulated Voltage VDD Conditions Pin PWM_D to GND, VIN = VIN(MIN) (Note 6) VIN = VIN(MIN) ~500V, (Note 8) lDD(ext) = 0, Gate pin open IDD(ext) VDD Current Available for External Circuitry UVLO VDD Under Voltage Lockout Threshold VDD rising ∆UVLO RPWM_D VCS(HI) VDD Under Voltage Lockout Hysteresis PWM_D Pull-Down Resistance Current Sense Threshold Voltage Typ Max AL9910 AL9910-5 Min 0.50 1 AL9910A 0.65 1.2 AL9910 AL9910-5 7.0 7.5 8.0 AL9910A 9.5 10 11 1.0 VIN = VIN(MIN) to 100V (Notes 8 & 9) VDD falling AL9910 AL9910-5 6.4 6.7 7 AL9910A 8.4 9 9.8 AL9910 AL9910-5 500 AL9910A 750 VPWM_D = 5V Full ambient temperature range (Note 10) AL9910 AL9910A AL9910-5 Unit mA V mA V mV 150 200 250 225 250 275 237.5 250 262.5 kΩ mV VGATE(HI) GATE High Output Voltage IOUT = 10mA VDD -0.3 VDD V VGATE(LO) GATE Low Output Voltage IOUT = -10mA 0 0.3 V ROSC = 1MΩ 20 25 30 ROSC = 226kΩ 80 100 120 Oscillator Frequency fOSC DMAXhf Maximum Oscillator PWM Duty Cycle VLD Linear Dimming Pin Voltage Range tBLANK tDELAY fPWMhf = 25kHz, at GATE, CS to GND. Full ambient temperature range (Note 10), VIN = 20V Current Sense Blanking Interval VCS = 0.45V, VLD = VDD Delay From CS Trip to GATE lo VIN = 20V, VLD = 0.15, VCS = 0 to 0.22V after TBLANK kHz 100 % 0 - 250 mV 160 250 440 ns 300 ns tRISE GATE Output Rise Time CGATE = 500pF 30 50 ns tFALL GATE Output Fall Time CGATE = 500pF 30 50 ns TSD Thermal Shut Down 150 TSDH Thermal Shut Down Hysteresis 50 SO-8 (Note 11) SO-8EP (Note 12) SO-8 (Note 11) Thermal Resistance Junction-to-Case SO-8EP (Note 12) 110 66 22 9 θJA θJC Notes: Thermal Resistance Junction-toAmbient °C °C/W °C/W 8. VIN(MIN) for the AL9910 is 15V and for the AL9910A it is 20V. 9. Also limited by package power dissipation limit, whichever is lower. 10. Full ambient temperature range for AL9910-5S, AL9910AS and AL9910S is -40 to +85°C; for AL9910-5SP, AL9910ASP and AL9910SP is -40°C to +105°C. 11. Device mounted on FR-4 PCB (25mm x 25mm 1oz copper, minimum recommended pad layout on top. For better thermal performance, larger copper pad for heat-sink is needed. 12. Device mounted on FR-4 PCB (51mm x 51mm 2oz copper, minimum recommended pad layout on top layer and thermal vias to bottom layer ground plane. For better thermal performance, larger copper pad for heat-sink is needed. AL9910/ AL9910A/ AL9910-5 Document number: DS35103 Rev. 8 - 2 4 of 15 www.diodes.com December 2012 © Diodes Incorporated AL9910/ AL9910A/ AL9910-5 3.0 460 2.5 440 2.0 420 INPUT CURRENT (µA) CURRENT SENSE THRESHOLD (mV) Typical Characteristics 1.5 1.0 0.5 0.0 V IN = 400V 400 V IN = 15V 380 360 340 -0.5 320 -1.0 300 -1.5 -40 280 -40 -15 10 35 60 85 AMBIENT TEMPERATURE (°C) Change in Current Sense Threshold vs. Ambient Temperature 450 SHORT CIRCUIT OUTPUT CURRENT (mA) ILED = 281mA V IN = 264V TA = 23.5C 80 IO UT MAX (%) 70 60 50 40 30 20 10 0 85 Input Current vs. Ambient Temperature 100 90 -15 10 35 60 AMBIENT TEMPERATURE (° C) 0 50 100 150 200 250 V LD DIMMING CONTROL (mV) I OUT MAX vs. V LD Dimming Control ILED(NOM) = 180mA 400 350 300 250 200 150 85 105 125 145 165 185 205 225 245 265 INPUT VOLTAGE (VRMS ) 180mA LED Driver Short Circuit Output Current vs. Input Voltage 300 1.5 CHANGE IN FREQUENCY (%) 1.0 0.5 0.0 R OSC = 226kΩ -0.5 ROSC = 1M Ω -1.0 -1.5 -2.0 -40 -15 10 35 60 85 AMBIENT TEMPERATURE (°C) Change in Oscillation Frequency vs. Ambient Temperature AL9910/ AL9910A/ AL9910-5 Document number: DS35103 Rev. 8 - 2 5 of 15 www.diodes.com December 2012 © Diodes Incorporated AL9910/ AL9910A/ AL9910-5 Typical Characteristics (cont.) measured using AL9910EV4 200 95 15 LEDs 14 LEDs 190 18 LEDs EFFICIENCY (%) IOUT MAX (mA) 180 16 LEDs 170 17 LEDs 160 90 17 LEDs 14 LEDs 16 LEDs 85 15 LEDs 150 18 LEDs 140 85 80 85 105 125 145 165 185 205 225 245 265 INPUT VOLTAGE (VRMS ) 180mA LED Driver Output Current vs. Input Voltage 0.95 105 125 145 165 185 205 225 245 265 INPUT VOLTAGE (VRMS ) 180mA LED Driver Efficiency vs. Input Voltage 12 17 LEDs 18 LEDs 18 LEDs 0.9 POWER (W) POWER FACTOR 10 16 LEDs 0.85 17 LEDs 0.8 16 LEDs 8 15 LEDs 14 LEDs 15 LEDs 6 0.75 14 LEDs 0.7 85 105 125 145 165 185 205 225 245 265 INPUT VOLTAGE (VRMS ) 180mA LED Driver Power Factor vs. Input Voltage AL9910/ AL9910A/ AL9910-5 Document number: DS35103 Rev. 8 - 2 4 85 105 125 145 165 185 205 225 245 265 INPUT VOLTAGE (VRMS ) 180mA LED Driver Input Power Dissipation vs. Input Voltage 6 of 15 www.diodes.com December 2012 © Diodes Incorporated AL9910/ AL9910A/ AL9910-5 Application Information The AL9910 is very versatile and is capable of operating in isolated or non-isolated topologies. It can also be made to operate in continuous as well as discontinuous conduction mode. VIN VIN 7.5/10V LDO OSC ROSC VDD VDD 250mV S R LD O GATE CS OTP PWM_D 100k AL9910/AL9910A RSENSE GND Figure 1. Functional Block Diagram The AL9910 contains a high voltage LDO (see Figure 1) the output of the LDO provides a power rail to the internal circuitry including the gate driver. A UVLO on the output of the LDO prevents incorrect operation at low input voltage to the VIN pin. In a non-isolated Buck LED driver when the gate pin goes high the external power MOSFET Q1 is turned on causing current to flow through the LEDs, inductor (L1) and current sense resistor (RSENSE). When the voltage across RSENSE exceeds the current sense pin threshold the external MOSFET Q1 is turned off. The stored energy in the inductor causes the current to continue to flow through the LEDs via diode D1. The AL9910’s LDO provides all power to the rest of the IC including Gate drive this removes the need for large high power start-up resistors. This means that operate correctly it requires around 0.5mA from the high voltage power rail. The LDO can also be used to supply up to 1mA to external circuits. The AL9910 operates and regulates by limiting the peak current of the external MOSFET; the peak current sense threshold is nominally set at 250mV. The same basic operation is true for isolated topologies, however in these the energy stored in the transformer delivers energy to LEDs during the off-cycle of the external MOSFET. Design Parameters Setting the LED Current In the non-isolated buck converter topology, figure 1, the average LED current is not the peak current divided by 2 - however, there is a certain error due to the difference between the peak and the average current in the inductor. The following equation accounts for this error: R SENSE = 250mV (ILED + (0.5 * IRIPPLE ))) AL9910/ AL9910A/ AL9910-5 Document number: DS35103 Rev. 8 - 2 . 7 of 15 www.diodes.com December 2012 © Diodes Incorporated AL9910/ AL9910A/ AL9910-5 Applications Information (cont.) Setting Operating Frequency The AL9910 is capable of operating over a 25 and 300 kHz switching frequency range. The switching frequency is programmed by connecting an external resistor between ROSC pin and ground. The corresponding oscillator period is: tOSC = R osc + 22 µs 25 with ROSC in kΩ The switching frequency is the reciprocal of the oscillator period. Typical values for ROSC vary from 75kΩ to 1MΩ When driving smaller numbers of LEDs, care should be taken to ensure that tON > tBLANK. The simplest way to do this is to reduce/limit the switching frequency by increasing the ROSC value. Reducing the switching frequency will also improve the efficiency. When operating in buck mode the designer must keep in mind that the input voltage must be maintained higher than 2 times the forward voltage drop across the LEDs. This limitation is related to the output current instability that may develop when the AL9910 operates at a duty cycle greater than 0.5. This instability reveals itself as an oscillation of the output current at a sub-harmonic (SBO) of the switching frequency. The best solution is to adopt the so-called constant off-time operation as shown in Figure 2. The resistor (ROSC) is, connected to ground by default, to set operating frequency. To force the AL9910 to enter constant OFF time mode ROSC is connected to the gate of the external MOSFET. This will decrease the duty cycle from 50% by increasing the total period, tOFF + tON. VIN VDD LD VIN Q1 AL9910/A GATE CS PWM_D ROSC GND ROSC Figure 2. Constant Off-Time Configuration The oscillator period equation above now defines the AL9910 off time, tOFF. When using this mode the nominal switching frequency is chosen and from the nominal input and output voltages the off-time can be calculated: ⎛ VOUT(nom ) ⎞ ⎟∗ 1 t OFF = ⎜1 − ⎟ ⎜ V IN(nom ) ⎠ fOSC ⎝ ( ) From this the timing resistor, ROSC, can be calculated: R OSC = t OFF (µs) ∗ 25 − 22(kΩ ) Inductor Selection The non-isolated buck circuit, Figure 1, is usually selected and it has two operation modes: continuous and discontinuous conduction modes. A buck power stage can be designed to operate in continuous mode for load current above a certain level usually 15% to 30% of full load. Usually, the input voltage range, the output voltage and load current are defined by the power stage specification. This leaves the inductor value as the only design parameter to maintain continuous conduction mode. The minimum value of inductor to maintain continuous conduction mode can be determined by the following example. The required inductor value is determined from the desired peak-to-peak LED ripple current in the inductor; typically around 30% of the nominal LED current. L= (VIN − VLEDs ) × D (0.3 × ILED ) × fOSC Where D is duty cycle The next step is determining the total voltage drop across the LED string. For example, when the string consists of 10 High-Brightness LEDs and each diode has a forward voltage drop of 3.0V at its nominal current; the total LED voltage VLEDS is 30V. AL9910/ AL9910A/ AL9910-5 Document number: DS35103 Rev. 8 - 2 8 of 15 www.diodes.com December 2012 © Diodes Incorporated AL9910/ AL9910A/ AL9910-5 Applications Information (cont.) Dimming The LED brightness can be dimmed either linearly (using the LD pin) or via pulse width modulation (using the PWM-D pin); or a combination of both - depending on the application. Pulling the PWM_D pin to ground will turn off the AL9910. When disabled, the AL9910’s quiescent current is typically 0.5mA (0.65 for AL9910A). Reducing the LD voltage will reduce the LED current but it will not entirely turn off the external power transistor and hence the LED current – this is due to the finite blanking period. Only the PWM_D pin will turn off the power transistor. Linear dimming is accomplished by applying a 45mV to 250mV analog signal to the LD pin. This overrides the default 250mV threshold level of the CS pin and reduces the output current. If an input voltage greater than 250mV is applied to the LD then the output current will not change. The LD pin also provides a simple cost effective solution to soft start; by connecting a capacitor to the LD pin down to ground at initial power up the LD pin will be held low causing the sense threshold to be low. As the capacitor charges up the current sense threshold will increase thereby causing the average LED current to increase. PWM dimming is achieved by applying an external PWM signal to the PWM_D pin. The LED current is proportional to the PWM duty cycle and the light output can be adjusted between zero and 100%. The PWM signal enables and disables the AL9910 - modulating the LED current. The ultimate accuracy of the PWM dimming method is limited only by the minimum gate pulse width, which is a fraction of a percentage of the low frequency duty cycle. PWM dimming of the LED light can be achieved by turning on and off the converter with low frequency 50Hz to 1000Hz TTL logic level signal. With both modes of dimming it is not possible to achieve average brightness levels higher than the one set by the current sense threshold level of the AL9910. If a greater LED current is required then a smaller sense resistor should be used Output Open Circuit Protection The non-isolated buck LED driver topology provides inherent protection against an open circuit condition in the LED string due to the LEDs being connected in series with the inductor. Should the LED string become open circuit then no switching occurs and the circuit can be permanently left in this state with damage to the rest of the circuit. AC/DC Off-Line LED Driver The AL9910 is a cost-effective off-line buck LED driver-controller specifically designed for driving LED strings. It is suitable for being used with either rectified AC line or any DC voltage between 15V to 500V. See Figure 3 for typical circuit. LED + D1 VAC IN VDD C1 BR1 VIN C2 LD C3 L1 LED - AL9910/A PWM_D ROSC GND Q1 GATE CS RSENSE ROSC Figure 3. Typical Application Circuit (without PFC) Buck Design Equations: D= VLEDs VIN t ON = L≥ D fosc ( VIN − VLEDs ) × t ON 0.3 × ILED R SENSE = 0.25 where ILED x 0.3 = IRIPPLE ILED + (0.5 × (ILED × 0.3)) AL9910/ AL9910A/ AL9910-5 Document number: DS35103 Rev. 8 - 2 9 of 15 www.diodes.com December 2012 © Diodes Incorporated AL9910/ AL9910A/ AL9910-5 Applications Information (cont.) Design Example For an AC line voltage of 120V the nominal rectified input voltage VIN = 120V*1.41 = 169V. From this and the LED chain voltage the duty cycle can be determined: D = VLEDs /VIN = 30/169 = 0.177 From the switching frequency, for example fOSC = 50kHz, the required on-time of the external MOSFET can be calculated: tON = D/fOSC = 3.5 µs The value of the inductor for an LED current of 350mA is determined as follows: L = (VIN - VLEDs) * tON /(0.3 * ILED) = 4.6mH Input Bulk Capacitor For Offline lamps an input bulk capacitor is required to ensure that the rectified AC voltage is held above twice the LED string voltage throughout the AC line cycle. The value can be calculated from: CIN ≥ PIN × (1 − D CH ) 2 × VLINE _ MIN × 2fL × ΔVDC _ MAX Where Dch : Capacity charge work period, generally about 0.2 to 0.25 fL : Input frequency for full range (85 to 265VRMS) ΔVDC _ MAX Should be set 10 to15% of 2 VLINE _ MIN If the capacitor has a 15% voltage ripple then a simplified formula for the minimum value of the bulk input capacitor approximates to: I × VLEDs × 0.06 CMIN = LED VIN 2 Power Factor Correction If power factor improvement is required then for the input power less than 25W, a simple passive power factor correction circuit can be added to the AL9910 typical application circuit. Figure 4 shows that passive PFC circuitry (3 current steering diodes and 2 identical capacitors) does not significantly affect the rest of the circuit. Simple passive PFC improves the line current harmonic distortion and achieves a power factor greater than 0.85. Passive PFC LED + C4 C1 D1 VAC IN VDD BR1 LD C2 C3 VIN AL9910/A PWM_D ROSC GND Q1 LED L1 GATE CS RSENSE ROSC Figure 4. Typical Application Circuit with Passive PFC Each of these identical capacitors should be rated for half of the input voltage and have twice as much capacitance as the calculated CMIN of the buck converter circuit without passive PFC (see above section on bulk capacitor calculation). For further design information please see AN75 from the Diodes website. AL9910/ AL9910A/ AL9910-5 Document number: DS35103 Rev. 8 - 2 10 of 15 www.diodes.com December 2012 © Diodes Incorporated AL9910/ AL9910A/ AL9910-5 Applications Information (cont.) DC-DC Buck LED Driver The design procedure for an ac input buck LED driver outlined in the previous chapters equally applies DC input LED drivers. When driving long LED chains care should be taken not to induce SBO – maximum LED chain voltage should be less half of VIN. So either maximum duty cycle should be kept below 50% or use of constant off-time removes this issue. DC-DC Boost LED Driver Due to the topology of the AL9910 LED driver-controller it is capable of being used in boost configurations – at reduced accuracy. The accuracy can be improved by measuring the LED current with an op amp and use the op amp’s output to drive the LD pin. A Boost LED driver is used when the forward voltage drop of the LED string is higher than the input supply voltage. For example, the Boost topology can be appropriate when input voltage is supplied by a 48V power supply and the LED string consists of twenty HB LEDs, as the case may be for a street light. L1 VDD C1 VIN VIN D1 Q1 AL9910/A PWM_D GATE C2 LD ROSC CS C3 GND ROSC RSENSE Figure 5. Boost LED Driver In a Boost converter, when the external MOSFET is ON the energy is stored in the inductor which is then delivered to the output when the external MOSFET switches OFF. If the energy stored in the inductor is not fully depleted by the next switching cycle (continuous conduction mode) the DC conversion between input and output voltage is given by: VOUT = V − VIN VIN Î D = OUT VOUT 1− D From the switching frequency, fOSC, the on-time of the MOSFET can be calculated: t ON = D fOSC From this the required inductor value can be determined by: L= VIN ∗ t ON 0.3 ∗ ILED The Boost topology LED driver requires an output capacitor to deliver current to the LED string during the time that the external MOSFET is on. In boost LED driver topologies if the LEDs should become open circuit damage may occur to the power switch and so some form of detection should be present to provide Over-voltage detection/protection. AL9910/ AL9910A/ AL9910-5 Document number: DS35103 Rev. 8 - 2 11 of 15 www.diodes.com December 2012 © Diodes Incorporated AL9910/ AL9910A/ A A AL9910-5 Ordering Information n A AL9910 X XX XX - 13 Variant Blank : 7.5V 7 VDD A : 10V VDD Part Numberr AL9910-5S-13 AL9910-5SP-13 AL9910AS-13 AL9910ASP-13 AL9910S-13 AL9910SP-13 VCS Toleranc ce Pac ckage Blank : 10% % -5 : 5% S : SO-8 SP : SO-8EP VCS Tolerrance ckage Pac C Code Packaging ±5% ±5% ±10% % ±10% % ±10% % ±10% % S SP S S S SP S S SP SO-8 SO-8EP SO-8 SO-8EP SO-8 SO-8EP Packing 1 : 13” Tape 13 e & Reel 13” Tap pe and Reel Qua antity Part Numbe er Suffix 2500/Tap pe & Reel -13 2500/Tap pe & Reel -13 2500/Tap pe & Reel -13 2500/Tap pe & Reel -13 2500/Tap pe & Reel -13 2500/Tap pe & Reel -13 Marking In nformation n (1) SO-8 (2) SO-8EP AL9910/ AL9 9910A/ AL9910-5 Document numberr: DS35103 Rev. 8 - 2 12 of 15 www.diodes.com w December 2012 2 © Diodes Incorporate ed AL9910/ AL9910A/ AL9910-5 Package Outline Dimensions (All dimensions in mm.) Please see AP02002 at http://www.diodes.com/datasheets/ap02002.pdf for latest version. SO-8 0.254 (1) E1 E Gauge Plane Seating Plane A1 L Detail ‘A’ 7°~9° h 45° Detail ‘A’ A2 A A3 b e SO-8 Dim Min Max A 1.75 A1 0.10 0.20 A2 1.30 1.50 A3 0.15 0.25 b 0.3 0.5 D 4.85 4.95 E 5.90 6.10 E1 3.85 3.95 e 1.27 Typ h 0.35 L 0.62 0.82 0° 8° θ All Dimensions in mm D (2) SO-8EP Exposed Pad 8 5 E1 1 H 4 F b Bottom View E 9° (All sides) N 7° A e D A1 AL9910/ AL9910A/ AL9910-5 Document number: DS35103 Rev. 8 - 2 45° Q C 4° ± 3° Gauge Plane Seating Plane E0 L 13 of 15 www.diodes.com SO-8EP (SOP-8L-EP) Dim Min Max Typ A 1.40 1.50 1.45 A1 0.00 0.13 b 0.30 0.50 0.40 C 0.15 0.25 0.20 D 4.85 4.95 4.90 E 3.80 3.90 3.85 E0 3.85 3.95 3.90 E1 5.90 6.10 6.00 e 1.27 F 2.75 3.35 3.05 H 2.11 2.71 2.41 L 0.62 0.82 0.72 N 0.35 Q 0.60 0.70 0.65 All Dimensions in mm December 2012 © Diodes Incorporated AL9910/ AL9910A/ AL9910-5 Suggested Pad Layout Please see AP02001 at http://www.diodes.com/datasheets/ap02001.pdf for the latest version. (1) SO-8 X Dimensions X Y C1 C2 C1 Value (in mm) 0.60 1.55 5.4 1.27 C2 Y (2) SO-8EP X2 Dimensions C X X1 X2 Y Y1 Y2 Y1 Y2 X1 Y C AL9910/ AL9910A/ AL9910-5 Document number: DS35103 Rev. 8 - 2 Value (in mm) 1.270 0.802 3.502 4.612 1.505 2.613 6.500 X 14 of 15 www.diodes.com December 2012 © Diodes Incorporated AL9910/ AL9910A/ AL9910-5 IMPORTANT NOTICE DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION). Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes without further notice to this document and any product described herein. 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LIFE SUPPORT Diodes Incorporated products are specifically not authorized for use as critical components in life support devices or systems without the express written approval of the Chief Executive Officer of Diodes Incorporated. As used herein: A. Life support devices or systems are devices or systems which: 1. are intended to implant into the body, or 2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in significant injury to the user. B. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or to affect its safety or effectiveness. Customers represent that they have all necessary expertise in the safety and regulatory ramifications of their life support devices or systems, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any use of Diodes Incorporated products in such safety-critical, life support devices or systems, notwithstanding any devices- or systems-related information or support that may be provided by Diodes Incorporated. Further, Customers must fully indemnify Diodes Incorporated and its representatives against any damages arising out of the use of Diodes Incorporated products in such safety-critical, life support devices or systems. Copyright © 2012, Diodes Incorporated www.diodes.com AL9910/ AL9910A/ AL9910-5 Document number: DS35103 Rev. 8 - 2 15 of 15 www.diodes.com December 2012 © Diodes Incorporated