AP2972,2A,16V同步降压转换器
AN032_CN 降压转换器架构之比较(CM、CM_COT、ACOT)
Roland van RoyAN032 – Jan 20151. 简介 (2)2. 电流模式降压转换器 (2)3. 立锜之电流模式- COT（CMCOT）降压转换器 (4)4. 立锜之ADVANCED-COT (ACOT TM) 降压转换器 (5)5. 测量结果比较 (7)6. 总结 (10)降压转换器架构之比较1. 简介降压转换器被广泛应用于各种消费性和工业上的应用之中，其中常需转换器将较高的输入电压转换成一较低的输出电压。
现有的降压转换器效率非常好，并能在变化范围很大的输入电压和输出负载的条件下，仍产生调节良好的输出电压。
降压转换器有很多不同的回路控制方式：在过去，被广泛使用的是电压模式和电流模式，然而近来恒定导通时间（COT）架构也常被使用，而有些降压转换器则是同时由电流模式和恒定导通时间来控制的。
立锜的DC-DC 产品组合包含了多种降压转换器，包括电流模式（CM），电流模式-恒定导通时间（CMCOT）和先进恒定导通时间（ACOT™）等架构。
每种架构都有其优点和缺点，因此在实际应用中要选择降压转换器时，最好能先了解每种架构的特点。
2. 电流模式降压转换器电流模式降压转换器之内部功能框图显示于图一。
图一、电流模式转换器之内部功能框图在典型的电流模式控制中，会有一个恒定频率来启动高侧MOSFET，并有一误差放大器将反饋信号与参考电压作比较。
然后，电感电流的上升斜率再与误差放大器的输出作比较；当电感电流超过误差放大器的输出电压时，高侧MOSFET 即被关断(OFF)，而电感电流则流经低侧MOSFET，直等到下一个时钟来到。
电流斜坡再加上斜率补偿之斜坡是为要避免在高占空比时的次谐波振荡，并提高抗噪声性能。
电流模式转换器之回路带宽（F BW）是由误差放大器输出端的补偿元件来设定，通常设在远低于转换器的开关频率。
电流模式转换器之稳态和负载瞬态变化操作之波形显示于图二。
降压转换器架构之比较图二、电流模式转换器之稳态与负载瞬态的波形降压转换器架构之比较3. 立锜之电流模式- COT（CMCOT）降压转换器立锜之电流模式-COT 降压转换器之内部功能框图显示于图三。
常用替换运放型号对比
常⽤替换运放型号对⽐常⽤替换运放型号对⽐CA3130 ⾼输⼊阻抗运算放⼤器 Intersil[DATA] CA3140 ⾼输⼊阻抗运算放⼤器 CD4573 四可编程运算放⼤器 MC14573ICL7650 斩波稳零放⼤器 LF347(NS[DATA]) 带宽四运算放⼤器 KA347 LF351 BI-FET单运算放⼤器 NS[DATA] LF353 BI-FET双运算放⼤器 NS[DATA] LF356 BI-FET单运算放⼤器 NS[DATA] LF357 BI-FET单运算放⼤器 NS[DATA] LF398 采样保持放⼤器 NS[DATA] LF411 BI-FET单运算放⼤器 NS[DATA] LF412 BI-FET双运放⼤器 NS[DATA] LM124 低功耗四运算放⼤器(军⽤档) NS[DATA]/TI[DATA] LM1458 双运算放⼤器 NS[DATA] LM148 四运算放⼤器 NS[DATA] LM224J 低功耗四运算放⼤器(⼯业档)NS[DATA]/TI[DATA] LM2902 四运算放⼤器 NS[DATA]/TI[DATA] LM2904 双运放⼤器 NS[DATA]/TI[DATA] LM301 运算放⼤器 NS[DATA] LM308 运算放⼤器 NS[DATA] LM308H 运算放⼤器（⾦属封装） NS[DATA] LM318 ⾼速运算放⼤器NS[DATA] LM324(NS[DATA]) 四运算放⼤器 HA17324,/LM324N(TI) LM348 四运算放⼤器 NS[DATA] LM358 NS[DATA] 通⽤型双运算放⼤器 HA17358/LM358P(TI) LM380 ⾳频功率放⼤器NS[DATA] LM386-1 NS[DATA] ⾳频放⼤器NJM386D,UTC386 LM386-3 ⾳频放⼤器 NS[DATA] LM386-4 ⾳频放⼤器 NS[DATA] LM3886 ⾳频⼤功率放⼤器 NS[DATA] LM3900 四运算放⼤器 LM725 ⾼精度运算放⼤器NS[DATA] LM733 带宽运算放⼤器 LM741 NS[DATA] 通⽤型运算放⼤器HA17741 MC34119 ⼩功率⾳频放⼤器 NE5532 ⾼速低噪声双运算放⼤器 TI[DATA] NE5534 ⾼速低噪声单运算放⼤器TI[DATA] NE592 视频放⼤器 OP07-CP 精密运算放⼤器 TI[DATA] OP07-DP 精密运算放⼤器 TI[DATA] TBA820M ⼩功率⾳频放⼤器 ST[DATA] TL061 BI-FET单运算放⼤器 TI[DATA] TL062 BI-FET双运算放⼤器 TI[DATA] TL064 BI-FET 四运算放⼤器 TI[DATA] TL072 BI-FET双运算放⼤器 TI[DATA] TL074 BI-FET四运算放⼤器 TI[DATA] TL081 BI-FET单运算放⼤器TI[DATA] TL082 BI-FET双运算放⼤器 TI[DATA] TL084 BI-FET四运算放⼤器 TI[DATA] AD824 JFET输⼊,单电源,低电压,低功耗,精密四运算放⼤器 MC33171 单电源,低电压,低功耗运算放⼤器 AD826 低功耗,宽带,⾼速双运算放⼤器 MC33172 单电源,低电压,低功耗双运算放⼤器AD827 低功耗,⾼速双运算放⼤器 MC33174 单电源,低电压,低功耗四运算放⼤器 AD828 低功耗,宽带,⾼速双运算放⼤器 MC33178 ⼤电流,低功耗,低噪⾳双运算放⼤器 AD844 电流反馈型,宽带,⾼速运算放⼤器 MC33179 ⼤电流,低功耗,低噪⾳四运算放⼤器 AD846 电流反馈型,⾼速,精密运算放⼤器 MC33181 JFET输⼊,低功耗运算放⼤器 AD847 低功耗,⾼速运算放⼤器 MC33182 JFET输⼊,低功耗双运算放⼤器AD8531 COMS单电源,低功耗,⾼速运算放⼤器 MC33184 JFET 输⼊,低功耗四运算放⼤器 AD8532 COMS单电源,低功耗,⾼速双运算放⼤器 MC33201 单电源,⼤电流,低电压运算放⼤器AD8534 COMS单电源,低功耗,⾼速四运算放⼤器 MC33202 单电源,⼤电流,低电压双运算放⼤器 AD9617 低失真，电流反馈型,宽带,⾼速,精密运算放⼤器 MC33204 单电源,⼤电流,低电压四运算放⼤器 AD9631 低失真，宽带,⾼速运算放⼤器MC33272 单电源,低电压,⾼速双运算放⼤器 AD9632 低失真，宽带,⾼速运算放⼤器 MC33274 单电源,低电压,⾼速四运算放⼤器 AN6550 低电压双运算放⼤器 MC33282 JFET输⼊,宽带,⾼速双运算放⼤器AN6567 ⼤电流,单电源双运算放⼤器 MC33284 JFET输⼊,宽带,⾼速四运算放⼤器 AN6568 ⼤电流,单电源双运算放⼤器 MC33502 BIMOS,单电源,⼤电流,低电压,双运算放⼤器 BA718 单电源,低功耗双运算放⼤器MC34071A 单电源,⾼速运算放⼤器 BA728 单电源,低功耗双运算放⼤器 MC34072A 单电源,⾼速双运算放⼤器 CA5160 BIMOS,单电源,低功耗运算放⼤器 MC34074A 单电源,⾼速四运算放⼤器 CA5260 BIMOS,单电源双运算放⼤器 MC34081 JFET输⼊,宽带,⾼速运算放⼤器 CA5420 BIMOS,单电源,低电压,低功耗运算放⼤器 MC34082 JFET输⼊,宽带,⾼速双运算放⼤器 CA5470 BIMOS单电源四运算放⼤器 MC34084 JFET输⼊,宽带,⾼速四运算放⼤器CLC400 电流反馈型,宽带,⾼速运算放⼤器 MC34181 JFET输⼊,低功耗运算放⼤器 CLC406 电流反馈型,低功耗,宽带,⾼速运算放⼤器 MC34182 JFET输⼊,低功耗双运算放⼤器 CLC410 电流反馈型,⾼速运算放⼤器 MC34184 JFET输⼊,低功耗四运算放⼤器 CLC415 电流反馈型,宽带,⾼速四运算放⼤器 MC35071A 单电源,⾼速运算放⼤器 CLC449 电流反馈型,宽带,⾼速运算放⼤器 MC35072A 单电源,⾼速双运算放⼤器 CLC450 电流反馈型,单电源,低功耗,宽带,⾼速运算放⼤器 MC35074A 单电源,⾼速四运算放⼤器 CLC452 单电源,电流反馈型,⼤电流,低功耗,宽带,⾼速运算放⼤器 MC35081 JFET输⼊,宽带,⾼速运算放⼤器CLC505 电流反馈型,⾼速运算放⼤器 MC35082 JFET输⼊,宽带,⾼速双运算放⼤器 EL2030 电流反馈型,宽带,⾼速运算放⼤器 MC35084 JFET输⼊,宽带,⾼速四运算放⼤器 EL2030C 电流反馈型,宽带,⾼速运算放⼤器 MC35171 单电源,低电压,低功耗运算放⼤器 EL2044C 单电源,低功耗,⾼速运算放⼤器 MC35172 单电源,低电压,低功耗双运算放⼤器 EL2070 电流反馈型,宽带,⾼速运算放⼤器 MC35174 单电源,低电压,低功耗四运算放⼤器 EL2070C 电流反馈型,宽带,⾼速运算放⼤器 MC35181 JFET输⼊,低功耗运算放⼤器 EL2071C 电流反馈型,宽带,⾼速运算放⼤器 MC35182 JFET输⼊,低功耗双运算放⼤器 EL2073 宽带,⾼速运算放⼤器 MC35184 JFET输⼊,低功耗四运算放⼤器 EL2073C 宽带,⾼速运算放⼤器 MM6558 低电压,低失调电压,精密双运算放⼤器 EL2130C 电流反馈型,宽带,⾼速运算放⼤器MM6559 低电压,低失调电压,精密双运算放⼤器 EL2150C 单电源,宽带,⾼速运算放⼤器 MM6560 低电压,低失调电压,精密双运算放⼤器 EL2160C电流反馈型,宽带,⾼速运算放⼤器 MM6561 低功耗,低电压,低失调电压,精密双运算放⼤器 EL2165C 电流反馈型,宽带,⾼速,精密运算放⼤器 MM6564 单电源,低电压,低功耗,低失调电压,精密双运算放⼤器 EL2170C 单电源,电流反馈型,低功耗,宽带,⾼速运算放⼤器MM6572 低噪⾳,低电压,低失调电压,精密双运算放⼤器 EL2175C 电流反馈型,宽带,⾼速,精密运算放⼤器 NE5230单电源,低电压运算放⼤器 EL2180C 单电源,电流反馈型,低功耗,宽带,⾼速运算放⼤器NE5512 通⽤双运算放⼤器 EL2224 宽带,⾼速双运算放⼤器 NE5514 通⽤四运算放⼤器 EL2224C 宽带,⾼速双运算放⼤器NE5532 低噪⾳,⾼速双运算放⼤器 EL2232 电流反馈型,宽带,⾼速双运算放⼤器NE5534 低噪⾳,⾼速运算放⼤器 EL2232C 电流反馈型,宽带,⾼速双运算放⼤器 NJM2059 通⽤四运算放⼤器 EL2250C 单电源,宽带,⾼速双运算放⼤器 NJM2082 JFET输⼊,⾼速双运算放⼤器 EL2260C 电流反馈型,宽带,⾼速双运算放⼤器 NJM2107低电压,通⽤运算放⼤器 EL2270C 单电源,电流反馈型,低功耗,宽带,⾼速双运算放⼤器 NJM2112 低电压,通⽤四运算放⼤器EL2280C 单电源,电流反馈型,低功耗,宽带,⾼速双运算放⼤器 NJM2114 低噪⾳双运算放⼤器 EL2424 宽带,⾼速四运算放⼤器NJM2115 低电压,通⽤双运算放⼤器 EL2424C 宽带,⾼速四运算放⼤器 NJM2119 单电源,精密双运算放⼤器 EL2444C 单电源,低功耗,⾼速四运算放⼤器 NJM2122 低电压,低噪⾳双运算放⼤器 EL2450C 单电源,宽带,⾼速四运算放⼤器 NJM2130F 低功耗运算放⼤器 EL2460C 电流反馈型,宽带,⾼速四运算放⼤器 NJM2132 单电源,低电压,低功耗双运算放⼤器 EL2470C 单电源,电流反馈型,低功耗,宽带,⾼速四运算放⼤器 NJM2136 低电压,低功耗,宽带,⾼速运算放⼤器 EL2480C 单电源,电流反馈型,低功耗,宽带,⾼速四运算放⼤器NJM2137 低电压,低功耗,宽带,⾼速双运算放⼤器 HA-2640 ⾼耐压运算放⼤器 NJM2138 低电压,低功耗,宽带,⾼速四运算放⼤器 HA-2645 ⾼耐压运算放⼤器 NJM2140 低电压双运算放⼤器 HA-2839 宽带,⾼速运算放⼤器NJM2141 ⼤电流,低电压双运算放⼤器 HA-2840 宽带,⾼速运算放⼤器 NJM2147 ⾼耐压,低功耗双运算放⼤器 HA-2841 宽带,⾼速运算放⼤器 NJM2162 JFET输⼊,低功耗,⾼速双运算放⼤器HA-2842 宽带,⾼速运算放⼤器 NJM2164 JFET输⼊,低功耗,⾼速四运算放⼤器 HA-4741 通⽤四运算放⼤器 NJM3404A 单电源,通⽤双运算放⼤器 HA-5020 电流反馈型,宽带,⾼速运算放⼤器 NJM3414 单电源,⼤电流双运算放⼤器 HA-5127 低噪⾳,低失调电压,精密运算放⼤器 NJM3415 单电源,⼤电流双运算放⼤器 HA-5134 低失调电压,精密四运算放⼤器 NJM3416 单电源,⼤电流双运算放⼤器 HA-5137 低噪⾳,低失调电压,⾼速,精密运算放⼤器 NJM4556A ⼤电流双运算放⼤器 HA-5142 单电源,低功耗双运算放⼤器NJM4580 低噪⾳双运算放⼤器 HA-5144 单电源,低功耗四运算放⼤器 NJU7051 CMOS单电源,低功耗,低电压,低失调电压运算放⼤器 HA-5177 低失调电压,精密运算放⼤器 NJU7052 CMOS单电源,低功耗,低电压,低失调电压双运算放⼤器 HA-5221 低噪⾳,精密运算放⼤器 NJU7054 CMOS单电源,低功耗,低电压,低失调电压四运算放⼤器 HA-5222 低噪⾳,精密双运算放⼤器 NJU7061 CMOS单电源,低功耗,低电压,低失调电压运算放⼤器 HA-7712 BIMOS,单电源,低功耗,精密运算放⼤器NJU7062 CMOS单电源,低功耗,低电压,低失调电压双运算放⼤器 HA-7713 BIMOS,单电源,低功耗,精密运算放⼤器 NJU7064 CMOS单电源,低功耗,低电压,低失调电压四运算放⼤器 HA16118 CMOS单电源,低电压,低功耗双运算放⼤器 NJU7071 CMOS 单电源,低功耗,低电压,低失调电压运算放⼤器 AD704 低偏置电流,低功耗,低失调电压,精密四运算放⼤器 MAX430 CMOS单电源运算放⼤器 AD705 低偏置电流,低功耗,低失调电压,精密运算放⼤器 MAX432 CMOS 单电源运算放⼤器 AD706 低偏置电流,低功耗,低失调电压,精密双运算放⼤器 MAX4330 单电源,低电压,低功耗运算放⼤器 AD707 低失调电压,精密运算放⼤器MAX4332 单电源,低电压,低功耗双运算放⼤器AD708 低失调电压,精密双运算放⼤器 MAX4334 单电源,低电压,低功耗四运算放⼤器 AD711 JFET输⼊,⾼速,精密运算放⼤器 MAX473 单电源,低电压,宽带,⾼速运算放⼤器 AD712 JFET输⼊,⾼速,精密双运算放⼤器 MAX474 单电源,低电压,宽带,⾼速双运算放⼤器 AD713 JFET输⼊,⾼速,精密四运算放⼤器MAX475 单电源,低电压,宽带,⾼速四运算放⼤器AD744 JFET输⼊,⾼速,精密运算放⼤器 MAX477 宽带,⾼速运算放⼤器 AD745 JFET输⼊,低噪⾳,⾼速运算放⼤器 MAX478 单电源,低功耗,精密双运算放⼤器AD746 JFET输⼊,⾼速,精密双运算放⼤器 MAX478A 单电源,低功耗,精密双运算放⼤器 AD795 JFET输⼊,低噪⾳,低功耗,精密运算放⼤器 MAX479 单电源,低功耗,精密四运算放⼤器 AD797 低噪⾳运算放⼤器MAX479A 单电源,低功耗,精密四运算放⼤器 AD8002 电流反馈型,低功耗,宽带,⾼速双运算放⼤器MAX480 单电源,低功耗,低电压,低失调电压,精密运算放⼤器 AD8005 电流反馈型,低功耗,宽带,⾼速双运算放⼤器 MAX492C 单电源,低功耗,低电压,精密双运算放⼤器AD8011 电流反馈型,低功耗,宽带,⾼速运算放⼤器 MAX492E 单电源,低功耗,低电压,精密双运算放⼤器 AD8031 单电源,低功耗,⾼速运算放⼤器 MAX492M 单电源,低功耗,低电压,精密双运算放⼤器 AD8032 单电源,低功耗,⾼速双运算放⼤器MAX494C 单电源,低功耗,低电压,精密四运算放⼤器 AD8041 单电源,宽带,⾼速运算放⼤器 MAX494E 单电源,低功耗,低电压,精密四运算放⼤器 AD8042 单电源,宽带,⾼速双运算放⼤器 MAX494M 单电源,低功耗,低电压,精密四运算放⼤器 AD8044 单电源,宽带,⾼速四运算放⼤器 MAX495C 单电源,低功耗,低电压,精密运算放⼤器 AD8047 宽带,⾼速运算放⼤器 MAX495E 单电源,低功耗,低电压,精密运算放⼤器AD8055 低功耗,宽带,⾼速运算放⼤器 MAX495M 单电源,低功耗,低电压,精密运算放⼤器 AD8056 低功耗,宽带,⾼速双运算放⼤器 MC1458 通⽤双运算放⼤器 AD8072 电流反馈型,宽带,⾼速双运算放⼤器MC1458C 通⽤双运算放⼤器 AD812 电流反馈型,低电压,低功耗,⾼速双运算放⼤器 MC33071A 单电源,⾼速运算放⼤器AD817 低功耗,宽带,⾼速运算放⼤器 MC33072A 单电源,⾼速双运算放⼤器 AD818 低功耗,宽带,⾼速运算放⼤器 MC33074A 单电源,⾼速四运算放⼤器 AD820 JFET输⼊,单电源,低电压,低功耗,精密运算放⼤器 MC33078 低噪⾳双运算放⼤器 AD822 JFET输⼊,单电源,低电压,低功耗,精密双运算放⼤器MC33079 低噪⾳四运算放⼤器 AD823 JFET输⼊,单电源,低电压,低功耗,精密,⾼速双运算放⼤器 MC33102 低功耗双运算放⼤器 HA16119 CMOS单电源,低电压,低功耗双运算放⼤器 NJU7072 CMOS单电源,低功耗,低电压,低失调电压双运算放⼤器 HFA1100 电流反馈型,宽带,⾼速运算放⼤器 NJU7074 CMOS单电源,低功耗,低电压,低失调电压四运算放⼤器 HFA1120 电流反馈型,宽带,⾼速运算放⼤器 OP-07 低漂移,精密运算放⼤器 HFA1205电流反馈型,低功耗,宽带,⾼速双运算放⼤器 OP-113 BICMOS单电源,低噪⾳,低失调电压,精密运算放⼤器 HFA1245 电流反馈型,低功耗,宽带,⾼速双运算放⼤器 OP-150 COMS,单电源,低电压,低功耗 ICL7611 CMOS低电压,低功耗运算放⼤器 OP-160 电流反馈型,⾼速运算放⼤器 ICL7612 CMOS低电压,低功耗运算放⼤器 OP-162 单电源,低电压,低功耗,⾼速,精密运算放⼤器ICL7621 CMOS低电压,低功耗双运算放⼤器 OP-177 低失调电压,精密运算放⼤器 ICL7641 CMOS低电压四运算放⼤器OP-183 单电源,宽带运算放⼤器 ICL7642 CMOS低电压,低功耗四运算放⼤器 OP-184 单电源,低电压,⾼速,精密运算放⼤器ICL7650S 稳压器 OP-191 单电源,低电压,低功耗运算放⼤器 LA6500 单电源，功率OP 放⼤器 OP-193 单电源,低电压,低功耗,精密运算放⼤器 LA6501 单电源，功率OP放⼤器 OP-196 单电源,低电压,低功耗运算放⼤器 LA6510 2回路单电源功率OP放⼤器 OP-200 低功耗,低失调电压,精密双运算放⼤器" LA6512 ⾼压,功率OP放⼤器双运算放⼤器 OP-213 BICMOS单电源,低噪⾳,低失调电压,精密双运算放⼤器 LA6513 ⾼压,功率OP放⼤器双运算放⼤器 OP-250 COMS,单电源,低电压,低功耗双运算放⼤器LA6520 单电源,功率OP放⼤器三运算放⼤器 OP-260 电流反馈型,⾼速双运算放⼤器 LF356 JFET输⼊，⾼速运算放⼤器 OP-262 单电源,低电压,低功耗,⾼速,精密双运算放⼤器 LF356A JFET输⼊，⾼速运算放⼤器 OP-27 低噪⾳,低失调电压,精密运算放⼤器 LF411 JFET输⼊，⾼速运算放⼤器 OP-270 低噪声,低失调电压,精密双运算放⼤器 LF411A JFET输⼊，⾼速运算放⼤器 OP-271 精密双运算放⼤器 LF412 JFET输⼊，⾼速双运算放⼤器 OP-275 ⾼速双运算放⼤器 LF412A JFET输⼊，⾼速双运算放⼤器 OP-279 单电源,⼤电流双运算放⼤器 LF441 低功耗，JFET输⼊运算放⼤器 OP-282 JFET输⼊,低功耗双运算放⼤器 LF441A 低功耗，JFET输⼊运算放⼤器 OP-283 单电源,宽带双运算放⼤器 LF442 低功耗，JFET输⼊双运算放⼤器 OP-284 单电源,低电压,⾼速,精密双运算放⼤器 LF442A 低功耗，JFET输⼊双运算放⼤器OP-290 单电源,低功耗,精密双运算放⼤器 LF444 低功耗，JFET输⼊四运算放⼤器 OP-291 单电源,低电压,低功耗双运算放⼤器 LF444A 低功耗，JFET输⼊四运算放⼤器 OP-292 BICMOS单电源,通⽤双运算放⼤器 LM2902 单电源四运算放⼤器 OP-293 单电源,低电压,低功耗,精密双运算放⼤器 LM2904 单电源双运算放⼤器 OP-295 BICMOS低功耗,精密双运算放⼤器 LM324 单电源四运算放⼤器 OP-296 单电源,低电压,低功耗双运算放⼤器 LM358 单电源双运算放⼤器 OP-297 低电压,低功耗,低漂移,精密双运算放⼤器LM4250 单程控、低功耗运算放⼤器 OP-37 低噪⾳,低失调电压,⾼速,精密运算放⼤器 LM607 低失调电压,精密运算放⼤器 OP-400 低功耗,低失调电压,精密四运算放⼤器 LM6118 宽带,⾼速双运算放⼤器OP-413 BICMOS单电源,低噪⾳,低失调电压,精密四运算放⼤器。
低功耗半导体 LP6498A 600KHz 36V 1.2A 同步降压转换器 初步数据表说明书
600KHz 36V/1.2A Synchronous Step-down ConverterGeneral DescriptionThe LP6498A is a synchronous step-down regulatorfromahighvoltageinputsupply.Operating with an input voltage range from 4.5V to 30V.1.2A continuous output current .The converter integrates a main switch and a synchronous rectifier for high efficiency without an external Schottky diode. LP6498A Requires a minimum number of readily available standard external components.over current protection and thermal shutdown . output short circuit protection. The LP6498A converters are available in the industry standard SOT23-6 packages.Order InformationLP6498A□ □ □F: Pb-FreePackage TypeB6:SOT23-6Applications✧ Car Charger / Adaptor✧ Pre-Regulator for Linear Regulators ✧ Distributed Power Systems✧ USB Dedicated Charging Ports (DCP)Features◆ Input Voltage Range: 4.5V to 30V ◆ Output Voltage Range: 0.8V to 12V◆ 1200mA Load Current ◆ Up to 93% Efficiency◆ 600KHz Switching Frequency◆ Short Circuit Protection ◆ Thermal Fault Protection ◆ S O T 23-6 Package◆ RoHS Compliant and 100% Lead (Pb)-FreeTypical Application CircuitMarking InformationVINFunctional Pin DescriptionPin DescriptionNC No connection.GND Ground.FB Feedback Input.Vout=(R1R2+1)×V FBFunction DiagramAbsolute Maximum Ratings✧VIN\SW \EN to GND ---------------------------------------------------------------------------------------------- -0.3V to 36V ✧VOUT\LED\RV\FB to GND --------------------------------------------------------------------------------------- -0.3V to 6.5V ✧Maximum Junction Temperature -------------------------------------------------------------------------------------- 150°C ✧Storage Temperature ------------------------------------------------------------------------------------------ -65℃ to 165℃✧Operating Ambient Temperature Range (TA) ------------------------------------------------------------- -20℃ to 85°C ✧Maximum Soldering Temperature (at leads, 10 sec) ------------------------------------------------------------- 260°CNote 1. Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied.Exposure to absolute maximum rating conditions for extended periods may affect device reliability.Thermal Information✧Maximum Power Dissipation (SOT23-6, P D, T A=25℃) ------------------------------------------------------------ 0.6W ✧Thermal Resistance (SOT23-6, θJA) ------------------------------------------------------------------------------ 200℃/W ESD Susceptibility✧HBM(Human Body Mode) -------------------------------------------------------------------------------------------------- 2KV ✧MM(Machine Mode) --------------------------------------------------------------------------------------------------------- 200VElectrical CharacteristicsV IN=12V, V EN=5V, T A=25℃, unless otherwise notedHiccup Time 6Soft-start Time0.8Oscillator Frequency 600Typical Operating CharacteristicsOperation InformationFunctional DescriptionThe LP6498A is a switch-mode step-down DC-DC converter. The device operates at a fixed 600KHz switching frequency, and uses a slope compensated current mode architecture. This step-down DC-DC converter can supply up to 1.2A output current at input voltage range from 4.5V to 30V. It minimizes external component size and optimizes efficiency at the heavy load range. The integrated slope compensation allows the device to remain stable over a wider range of inductor values so that smaller values (6.8μH to 22μH) with lower DCR can be used to achieve higher efficiency. Layout GuidanceWhen laying out the PCB board, the following layout guideline should be followed to ensure proper operation of the LP6498A:1. The power traces, including the GND trace, the SW trace and the IN trace should be kept short, direct and wide to allow large current flow. The L connection to the SW pins should be as short as possible. Use several VIN pads when routing between layers.2. The input capacitor (C IN) should connect as closely as possible to VIN and GND to get good power filtering.Packaging InformationSOT23-6。
ADP2323 双通道、3 A、20 V同步降压调节器，集成高端MOSFET 数据手册说明书
典型应用电路INTVCC R TOP1C C1R C1C SS1C INTC DRVC IN1C BST1C BST2L1M1M2L2V INV INV OUT1C OUT1C OUT2V OUT2R BOT1R TOP2R C2C C2C SS2C IN2R BOT2R OSCF B 1C O M P 1S S 1E N 1P V I N 1B S T 1F B 2C O M P 2S S 2E N 2P V I N 2B S T 2MODE SCFG TRK2TRK1VDRV ADP2323GND PGOOD2PGOOD1SYNCRTSW1DL1PGND DL2SW209357-001图1.5055606570758085909510000.51.01.52.02.53.0E F F I C I E N C Y (%)OUTPUT CURRENT (A)V OUT = 5V V OUT = 3.3V09357-002图2.效率与输出电流的关系(V IN = 12 V ，f SW = 600 kHz)双通道、3 A 、20 V 同步降压调节器，集成高端MOSFET 数据手册ADP2323产品特性输入电压：4.5 V 至20 V 输出精度：±1%集成典型值90 mΩ的高端MOSFET 灵活的输出配置双路输出：3 A/3 A 单路交错式输出：6 A可编程开关频率：250 kHz 至1.2 MHz外部同步输入，可编程相移，或内部时钟输出可选PWM 或PFM 工作模式小型电感的限流可调外部补偿和软启动启动后进入预充电输出受ADIsimPower ™设计工具支持应用通信基础设施网络和服务器工业和仪器仪表医疗保健中间供电轨转换DC-DC 负载点应用概述ADP2323是一款功能全面的双通道降压DC-DC 调节器，采用电流模式架构。
ADP2323集成两个高端功率MOSFET 开关和两个低端驱动器，可控制外部的N 沟道MOSFET 。
美国Eaton公司VSA12、VSA16和VSA20型号的自动切换断路器功能说明说明书
ReclosersFunctional Specification GuideTypes VSA12, VSA16 and VSA20 ReclosersPS280014EN1 of 3 • Effective June 2017 • Supersedes all previousFunctional specification for Types VSA12, VSA16 and VSA20 reclosers1. Equipment Specifications1.1. Automatic circuit reclosers with vacuum interruption and air insulation2. Standards2.1. The recloser covered by this specification shall be designed, manufactured and tested in accordance withapplicable ANSI C37.60 and ANSI C37.61. 3. Quality3.1. The manufacturing facility shall be independently certified to meet ISO 9001 Standards.4. RatingsVSA12 VSA16 VSA20 Maximum Design Voltage (kV) 15.5 15.5 15.5 Nominal Operating Voltage (kV) 2.4-14.42.4-14.42.4-14.4 Basic Insulation Level-BIL (kV) 110 110 110 60 Hertz Withstand Voltage (kV) Dry, one minute 50 50 50Wet, ten seconds45 45 45 Max RIV at 1.0 MHZ/9.41 kV (microvolts) 100 100 100 Continuous Current rating (amps) 800 800 800 Symmetric Interrupting Current (amps)12,000 16,00020,000 Cable Charging Current (amps) 2 2 2 Magnetizing Current (amps) 28 28 28 General Purpose Capacitance Current 250 250 250Switching (amps)3 Second Current, Symmetric (amps) 12,000 16,000 20,000 Momentary Current, Asymmetric (amps) 19,20025,60032,0005. Mechanical Life5.1. 2500 Close-Open operations6. Duty cyclePERCENT OF NUMBER OF MAXIMUM INTERRUPTING UNIT CIRCUIT RATING OPERATIONS X/R RATIO 15-2088445-55 112 890-100 32 167. Features7.1. The recloser will be mechanically and electrically trip-free7.2. All three poles of the recloser will be operated simultaneously by a solenoid-spring operating mechanism.7.3. The recloser will be opened and closed by means of energy provided by a motor operating at 240 Vac, 60Hz and stored in springs for both tripping and closing operations.7.4. Bushings will be of “wet” process porcelain and will have a standard creepage distance of 12" inches. A17" creepage distance bushing will be available as an option.7.5. Bushing terminals will be of the universal clamp type and will accommodate conductors ranging in sizefrom 4/0 to 1000 MCM, inclusive,7.6. Current interruption will occur in vacuum interrupters, one interrupter per phase.7.7. It will be possible to replace one or all bushings without any re-alignment or adjustment of the vacuuminterrupters or operating mechanism.7.8. The recloser interrupting time will be 0.042 seconds7.9. Resistance-type heaters will be provided in the interrupter and operating mechanism cabinets, to preventmoisture condensation.7.10. The recloser will be shipped mounted in a substation mounting frame.7.11. The mounting frame extension will have a ground pad which will accommodate two No. 2/0 to 250 MCMconductors7.12. Sensing bushing current transformers, 1000:1 ratio, for use with the recloser control, will be mountedinternally in the recloser on bushings 1, 3, and 5.7.13. A 4 - digit counter will be provided in the operating mechanism.7.14. The recloser will use a motor operator to charge opening and closing springs; solenoids will be used forthe tripping and closing operations.7.15. A contact position indicator, externally visible, will be provided.7.16. Two external pull rings will be provided, one to close the recloser and one to trip the recloser.7.17. A spring operator condition indicator will be provided to indicate whether the closing springs are energized.The indicator consists of a mechanical flag for indication and will be visible from the front of the operatorcabinet.7.18. The recloser will be capable of manual trip and manual close on a maximum fault. Closing springs can becharged manually by means of a crank (150 turns), through a gear box.8. Spring Charging MotorSTANDARD ACCESSORYOperating voltage (Vac) 240 120Voltage Range (Vac) 160-257 90-127Maximum Current RMSA (amperes) 13 18Steady State Current (amperes) 8 9Motor Running Time (cycles) 40 409. Controls9.1. The recloser will be capable of operation with any of the following: Form 3, Form 3A, Form 4A or Form 4CType ME Recloser control.10. Approved ManufacturersEaton。
AP2952 V2.5中文
2A, 18V 同步整流降压转换器概述AP2952是一款单片同步整流降压稳压器，它集成了导通阻抗130mΩ的MOSFET，可以在很宽的输入电压范围（4.75V-18V）内提供2A的负载能力。
电流模式控制使其具有很好的瞬态响应和单周期内的限流功能。
可调的软启动时间能避免开启瞬间的冲击电流，在停机模式下，输入电流小于1uA。
AP2952封装为SOP8, 同时提供了紧凑的系统方案，可以最大限度的减少外围元件。
应用z分立式电源系统z网络系统z FPGA, DSP, ASIC电源z绿色电子产品z笔记本电脑特性z2A输出电流z输入电压范围4.75V到18Vz内部集成130mΩ的功率MOSFETz输出可调范围为0.925V到15Vz效率可达95%z可调软启动时间z外围使用低ESR瓷片电容可保证其稳定工作z固定的450kHz工作频率z每个周期内都有限流功能z具有欠压保护功能z散热能力较强的SOP8封装封装SOP8典型应用电路图图1 典型应用电路图典型效率曲线1200图2 典型效率曲线引脚说明引脚序号 引脚名称引脚描述1BS 上管栅极驱动升压输入。
BS 为上管N 沟道MOSFET 开关提供驱动。
从SW 到BS 端连接一个0.01uF 或更大的电容。
2IN电源输入。
为IC 以及降压转换器开关提供输入电源。
在4.75V 至18V 的电压范围驱动IN 。
通过一个适当的大电容旁路IN 到地，以消除输入IC 的噪声。
3SW 功率开关输出。
SW 为开关节点提供电源输出。
从SW 端到输出负载连接输出LC 滤波器。
请注意，从SW 到BS 需要接一个电容。
4 GND 电源地。
5FB反馈输入端。
FB 侦测输出电压来调节这个电压。
通过来自输出电压的一个电阻分压器驱动FB 。
反馈阈值电压是0.925V 。
6COMP 补偿节点。
COMP 用来补偿调节控制回路。
从COMP 脚到GND 连接一个RC 网络来补偿调节控制回路。
在某些情况下，从COMP 到GND 之间必须接一个额外的电容。
上海图一实业 降压型开关稳压电源控制器 AE2576技术说明书
降压型开关稳压电源控制器概述AE2576是降压型开关稳压器，具有非常小的电压调整率和电流调整率，具有3A的负载驱动能力，AE2576能够输出3.3V、5V、12V、15V的固定电压和电压可调节的可调电压输出方式。
AE2576应用时比较简单且外围元件较少，内置频率补偿电路和固定频率振荡器。
AE2576系列产品的开关频率为52KHz，所以应用时可以使用小尺寸的滤波元件。
AE2576可以高效的取代一般的三端线性稳压器，它能够充分的减小散热片的面积，在一些应用条件下甚至可以不使用散热片。
在规定的输入电压和输出负载的条件下，AE2576输出电压的误差范围为±4％；振荡器的振荡频率误差范围为±10％；典型的待机电流为50μA，芯片内置过流保护电路和过热保护电路。
特点■ 3.3V、5V、12V、15V的固定电压输出和可调节电压输出■可调节电压输出的范围为1.23V到30V，其线性调整率和负载调整率最大可以有±4％的误差。
■负载电流达到3A■输入电压达到36V■只需四个外围元件■内置固定频率为52kHz的振荡器■高效率■内置过热保护电路和过流保护电路应用领域■高效降压型调节器■正、负电压转换器典型应用图图1：固定电压输出模式功能框图3.3v R2=1.7K 5v R2=3.1K 12v R2=8.4K15v R2=11.3K For Adjustable R2=0K R1=open 管脚图5-Lead TO-220(T) 5-Lead TO-263(S)管脚说明：V IN ― 正电源输入；为减小输入瞬态电压和给调节器提供开关电流，此管脚应接旁路电容V OUT ― 开关输出端，输出高电压为（V IN －V SAT ）GND ― 电路地端FEEDBACK― 反馈端― 待机端，低电平有效最大绝对额定值(注1)名 称范 围单 位最大电源电压 45 V脚输入电压-0.3～+ V IN V 到地的输出电压（静态） -1 V功 耗由内部限定 --储存温度 -65～+150℃最高工作结温 +150 ℃ESD 保护能力（人体放电）2 KV 气 焊（60秒）+215 ℃ TO-263 红外线焊接（10秒）+245 ℃ 焊接时的管脚温度 TO-220电烙铁焊接（10秒）+260℃ 温度范围 -40～+125℃工 作 条 件 电源电压 4.5～40 VAE2576-3.3 电气特性(说明：本参数适合于芯片结温T J =25℃)AE2576-3.3符 号参数说明条 件最小(注2)典型最大 (注2)单位系统参数 测试电路见图2(注3)V OUT 输出电压 6V ≤V IN ≤36V 0.5A ≤I LOAD ≤3A 3.168 3.3 3.432Vη 效率V IN =12V ，I LOAD =3A-- 75 -- %AE2576技术说明书 Ver1.0AE2576-5电气特性(说明：本参数适合于芯片结温T J=25℃)AE2576-5.0符号参数说明条件最小(注2) 典型最大(注2)单位系统参数测试电路见图2(注3)V OUT 输出电压8V≤V IN≤36V0.5A≤I LOAD≤3A4.800 55.200 Vη效率V IN=12V，I LOAD=3A-- 77 -- %AE2576-12电气特性(说明：本参数适合于芯片结温T J=25℃)AE2576-12符号参数说明条件最小(注2) 典型最大(注2)单位系统参数测试电路见图2(注3)V OUT 输出电压15V≤V IN≤36V0.5A≤I LOAD≤3A11.520 12 12.480 Vη效率V IN=15V，I LOAD=3A-- 88 -- %AE2576-15电气特性(说明：本参数适合于芯片结温T J=25℃)AE2576-12符号参数说明条件最小(注2) 典型最大(注2)单位系统参数测试电路见图2(注3)V OUT 输出电压18V≤V IN≤36V0.5A≤I LOAD≤3A14.400 15 15.600 Vη效率V IN=18V，I LOAD=3A-- 88 -- %AE2576-ADJ 电气特性(说明：本参数适合于芯片结温T J =25℃)AE2576-ADJ符 号参数说明条 件最小 (注2)典型最大 (注2)单位系统参数 测试电路见图2(注3)FB反馈电压 8V ≤V IN ≤36V 0.5A ≤I LOAD ≤3A V OUT =5V (见图2) 1.193 1.230 1.267Vη 效率V IN =12V ，I LOAD =3A V OUT =5V-- 77 -- %整体电特性除非特别说明，V IN =12V 适应于V OUT =3.3V 、5V 、ADJ ；V IN =25V 适应于V OUT =12V ，V IN =30V适应于VOUT =15V 。
Richtek Technology RT4720A 三通道DC DC增压转换器说明书
RT4720ATriple DC/DC Boost Converter for AMOLEDGeneral DescriptionRT4720A is a triple channels DC/DC converter which is designed to provide the power of AMOLED. It integrates step up DC/DC and an inverting converter to provide the positive and negative output voltage required by AMOLED.For the portable application, board space and efficiency are always major concerns. The high switching frequency of RT4720A allows the use of low inductance inductor to save the board space. It provides dual positive output voltage, one is a fixed 5.8V or 7.7V output voltage by SEL pin and the other positive output is fixed 4.6V. For the negative output voltage, it can be programmed by external MCU through single wire (SWIRE pin). The output voltage range of negative output voltage is -1.4V to -5.4V. RT4720A has OTP, SCP, UVLO and over current protections. The RT4720A is available in a WQFN -16L 3x3 package to achieve saving PCB space.Features●Boost Converter to Supply Positive AVDD Voltage Fixed 5.8V or 7.7V●Boost Converter to Supply AMOLED Positive Voltage 4.6V●Inverter Converter to Supply AMOLED Negative Voltage From -1.4V to -5.4V● Maximum Output Current up to 300mA for AMOLED Positive & Negative Power Supply●Maximum Output Current up to 50mA for Fixed 5.8V or 7.7V AVDD Output Voltage● Typical Peak Efficiency : 90% (40mA to 150mA) ● ********************************● High Output Voltage Accuracy ● Excellent Line and Load Transient ● Excellent Line and Load Regulation● Programmable Negative Voltage by SWIRE Pin ● Fast Outputs Discharge Function● Low Quiescent Current <1 A in Shutdown Mode ● Internal Soft Start to limit Inrush Current ● Over Temperature Protection (OTP) ● Over Current Protection (OCP) ●Short Circuit Protection (SCP)Applications● Cellular Phones ● Digital Cameras ● PDAs and Smart Phones ●Probable InstrumentSimplified Application CircuitVBAT V POSAVDD V NEGRT4720AOrdering InformationPackage TypeQW : WQFN-16L 3x3RT4720ALead Plating SystemG : Green (Halogen Free and Pb Free)Note :Richtek products are :④ RoHScompliant and compatible with the current requirements of IPC/JEDEC J-STD-020.④ Suitablefor use in SnPb or Pb-free solderingprocesses.Marking Information7Y= : Product Code YMDNN : Date CodePin Configurations(TOP VIEW)A V I N P G N D 2L X 3S E L LX1PGND1FBSLX2V O 3PVIN VO2N C E N O 3A G N D VO1SWIRE1211109131415161234876517AGNDWQFN-16L 3x3Functional Pin DescriptionRT4720AFunctional Block DiagramOperationThe RT4720A is a triple channels DC/DC converter which is designed to provide the power of AMOLED that can support the input voltage range from 2.9V to 4.5V. The VO1&VO2 output current can be up to 300mA, and the VO3 output current can be up to 50mA. The RT4720A uses current mode architecture for the purpose of high efficiency and high transient response. The VO1 positive output voltage is produced from the DC/DC Boost converter and is set at a typical value of 4.6V. When the SWIRE goes high, the positive output voltage will be enabled with an internal soft-start process. The VO2 negative output voltage is produced from the DC/DC Buck-Boost converter and the negative output voltage range is -1.4V to -5.4V. It can be programmed by external MCU through single wire (SWIRE pin). The VO3 positive output voltage is produced from the DC/DC Boost converter and is set at a fixed 7.7V or 5.8V by SEL pin. When SWIRE goes high and VO1 soft-start had finished already, negative output voltage VO2 will be enabled with an internal soft-start process.RT4720ATable 1. SWIRE Command LUT for VO2Table 2. SWIRE Pin CharacteristicsRT4720ATiming DiagramSWIRE Command Timing DiagramT en_dly< 400μs2μs < T off < 20μsPower SequenceT off_dly > 300μsRT4720AT> 300 sRT4720A Absolute Maximum Ratings(Note 1)●PVIN, AVIN, VO1, LX1, FBS, SEL, ENO3, SWIRE ----------------------------------------------------------- -0.3 to 6V●VO3, LX3 ---------------------------------------------------------------------------------------------------------------- -0.3 to 12V●VO2 ----------------------------------------------------------------------------------------------------------------------- -6 to 0.3V●LX2 ------------------------------------------------------------------------------------------------------------------------ -6 to 6V●Power Dissipation, P D @ T A = 25︒CWQFN-16L 3x3 -------------------------------------------------------------------------------------------------------- 3.33W●Package Thermal Resistance (Note 2)WQFN-16L 3x3, θJA -------------------------------------------------------------------------------------------------- 30︒C/WWQFN-16L 3x3, θJC -------------------------------------------------------------------------------------------------- 7.5︒C/W●Lead Temperature (Soldering, 10 sec.) -------------------------------------------------------------------------- 260︒C●Junction Temperature ------------------------------------------------------------------------------------------------ 150︒C●Storage Temperature Range --------------------------------------------------------------------------------------- -65︒C to 150︒C ●ESD Susceptibility (Note 3)HBM (Human Body Model) ----------------------------------------------------------------------------------------- 2kVMM (Machine Model) ------------------------------------------------------------------------------------------------- 200V Recommended Operating Conditions (Note 4)●Supply Input Voltage ------------------------------------------------------------------------------------------------- 2.9V to 4.5V●Ambient Temperature Range--------------------------------------------------------------------------------------- -40︒C to 85︒C ●Junction Temperature Range -------------------------------------------------------------------------------------- -40︒C to 125︒C Electrical Characteristics(V IN = 3.7V, V O1 = 4.6V, V O2 = -4V, V O3 = 7.7V, T A = 25︒C, unless otherwise specified)RT4720ART4720A Note 1. Stresses beyond those listed “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may affect device reliability.Note 2. θJA is measured at T A= 25︒C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is measured at the exposed pad of the package.Note 3. Devices are ESD sensitive. Handling precaution recommended.Note 4. The device is not guaranteed to function outside its operating conditions.RT4720ATypical Application CircuitVBAT V POS(Fixed 4.6V)AVDD (5.8V & 7.7V)V NEGTable 3. Typical BOM ListTypical Operating CharacteristicsVO1&VO2 Efficiency vs. Load Current707580859095100E f f i c i e n c y (%)VO3 Efficiency vs. Load Current6065707580859095100E f f i c i e n c y (%)4.564.574.584.594.604.614.624.634.64V P O S V o l t a g e (V )VNEG Voltage vs. Load Current-4.04-4.03-4.02-4.01-4.00-3.99-3.98-3.97-3.9600.050.10.150.20.250.3Load Current (A)V N E G V o l t a g e (V )7.667.677.687.697.707.717.727.737.7401020304050Loader Current (mA)A V D D V o l t a g e (V )V IN = 3.7VSWIRE (2V/Div)VO1(2V/Div)VO2(2V/Div)I IN(500mA/Div)Time (1ms/Div)VO1 & VO2 Power OnVO1 & VO2 Power OffTime (1ms/Div)SWIRE (2V/Div)VO1(2V/Div)VO2(2V/Div)I IN(500mA/Div)V IN = 3.7VVO3 Power OnTime (1ms/Div)VIN (2V/Div)ENO3(2V/Div)VO3(3V/Div)I IN(500mA/Div)V IN = 3.7VVO3 Power OffTime (1ms/Div)V IN = 3.7VVIN (2V/Div)ENO3(2V/Div)VO3(3V/Div)I IN(500mA/Div)Application InformationThe RT4720A is a triple channels DC/DC converter, which integrates dual step up converter and an inverting converter to provide the positive and negative output voltage required by AMOLED. RT4720A protection function includes Over Temperature Protection (OTP), Over Current Protection (OCP) and Short Circuit Protection (SCP), also it has Pulse Skipping Mode (PSM) to provide high efficiency during light load.Soft-StartThe RT4720A use an internal soft-start feature to avoid high inrush currents during step-up.Fast Discharge FunctionAll outputs voltage use an embedded discharge function to discharge the remaining output to 0V rapidly, preventing phenomena such as residual image on the display during shutdown.Over Temperature Protection (OTP)The RT4720A includes an Over Temperature Protection (OTP) feature to prevent excessive power dissipation from overheating the device. The OTP will shut down switching operation when junction temperature exceeds 140︒C. Once the junction temperature cools down by approximately 15︒C, the converter resumes operation.To maintain continuous operation, prevent the maximum junction temperature from rising above 125︒C.Over Current Protection (OCP)The RT4720A includes a current sensing circuitry which monitors the inductor current during each ON period. If the current value becomes greater than the current limit, the switch that pertains to inductor charging will turn off, forcing the inductor to leave charging stage and enter discharge stage.Short Circuit Protection (SCP)The RT4720A has an advanced short circuit protection mechanism which prevents damage to the device from unexpected applications. When the output voltage becomes lower than about 90%, over 1ms the device enters shutdown mode. VO3 can only re-start normal operation after triggering the ENO3 pin and VO1, VO2 can only re-start normal operation after triggering the SWIRE pin.Under Voltage Lockout (UVLO)To prevent abnormal operation of the IC in low voltage condition, an under voltage lockout is included, which shuts down the device at voltages lower than 2.2V. All functions will be turned off in this state.Input Capacitor SelectionEach channel input ceramic capacitors with 10μF capacitance are suggested for the RT4720A applications. However, to achieve best performance with the RT4720A, larger capacitance can be used. For better voltage filtering, select ceramic capacitors with low ESR, X5R and X7R types which are suitable because of their wider voltage and temperature ranges.Boost Inductor SelectionThe inductance depends on the maximum input current. As a general rule, the inductor ripple current range is 20% to 40% of the maximum input current. If 40% is selected as an example, the inductor ripple current can be calculated according to the following equations :OUT OUT(MAX)IN(MAX)INL IN(MAX)V II=ηVΔI= 0.4I⨯⨯⨯where η is the efficiency of the converter, I IN(MAX) is the maximum input current, and ΔI L is the inductor ripple current. The input peak current can then be obtained by adding the maximum input current with half of the inductor ripple current as shown in the following equation :I PEAK = 1.2×I IN(MAX)Note that the saturated current of the inductor must be greater than I PEAK.The inductance can eventually be determined according to the following equation :()()()2IN OUT IN2OUT OUT(MAX)OSCηV V-VL =0.4V I f⨯⨯⨯⨯⨯where f OSC is the switching frequency. For better system performance, a shielded inductor is preferred to avoid EMI problems.Boost Output Capacitor SelectionThe output ripple voltage is an important index for estimating chip performance. This portion consists of two parts. One is the product of the inductor peak current with the ESR of the output capacitor, while the other part is formed by the charging and discharging process of the output capacitor. As shown in Figure 1, ΔV OUT1 can be evaluated based on the ideal energy equalization. According to the definition of Q, the Q value can be calculated as the following equation :IN L OUT IN L OUT IN OUT OUT1OUT OSC111Q = I +ΔI -I +I -ΔI -I 222V 1= C V V f ⎡⎤⎛⎫⎛⎫⨯ ⎪ ⎪⎢⎥⎝⎭⎝⎭⎣⎦⨯⨯⨯where f OSC is the switching frequency and ΔI L is the inductor ripple current. Bring C OUT to the left side to estimate the value of ΔV OUT1 according to the following equation :OUTOUT1ESR OUT OSCD I ΔV = ΔV +ηC f ⨯⨯⨯where ESR C C_ESR PEAK C_ESR ΔV = ΔI R = I R ⨯⨯The output capacitor, C OUT , should be selected accordingly.Figure 1. The Output Ripple Voltage without theContribution of ESRAVDD Output Voltage SettingThe AVDD boost output voltage VO3 is fixed 7.7V or 5.8V output voltage by SEL pin. When SEL pin is set to high, the output voltage is 5.8V or otherwise SEL pin is set to low, the output voltage is changed to 7.7V.Buck-boost Converter Inductor SelectionThe first step in the design procedure is to verify whether the maximum possible output current of the buck-boost converter supports the specific application requirements. To simply the calculation, the fastest approach is to estimate converter efficiency by taking the efficiency numbers from provided efficiency curves or to use a worst case assumption for the expected efficiency, e.g., 80%. The calculation must be performed for the minimum assumed input voltage where the peak switch current is the highest. The inductor has an internal switch to be able to handle this current.④Converter Duty Cycle :OUT IN OUT-V D =V η-V ⨯④Maximum output current :()IN OUT PEAK OSC V D I = I -1-D 2f L ⎛⎫⨯⨯ ⎪⨯⨯⎝⎭④Inductor peak current :OUT IN PEAK OSC I V DI =+1-D 2f L⨯⨯⨯ As for inductance, we are going to derive the transition point, where the converter toggles from CCM to DCM. We need to define the point at which the inductor current ripple touches zero, and as the power switch SW is immediately reactivated, the current ramps up again. Figure 2 portrays the input current activity of the buck-boost converter.Figure 2. The Buck-Boost Input Signature in BCM The inductance can eventually be determined according to the following equation :2OUT INcritical OSC OUT IN OUTV ηV L = 2f I V +V ⎛⎫⨯⨯⎪ ⎪⨯⨯⎝⎭Buck-Boost Converter Output Capacitor Selection For the best output voltage filtering, low ESR ceramic capacitors are recommended. One 10μF output capacitors with sufficient voltage ratings in parallel are adequate for most applications. Additional capacitors can be added to improve load transient response. To calculate the output voltage ripple, the following equations can be used :OUT ESR OSC LOAD OUTD V ΔV =+ΔV f R C ⨯⨯⨯where ESR C C_ESR PEAK C_ESR ΔV = ΔI R = I R ⨯⨯ΔV ESR can be neglected in many cases since ceramic capacitors provides very low ESR.Negative Output Voltage SettingBuck-boost converter is implementing a pulse dimming method to control the output voltage (VO2) and its value is from -1.4V to -5.4V in 0.1V increments. User can control VO2 by SWIRE command. See SWIRE command section for details on how to adjust the output voltage.Thermal ConsiderationsFor continuous operation, do not exceed absolute maximum junction temperature. The maximum power dissipation depends on the thermal resistance of the IC package, PCB layout, rate of surrounding airflow, and difference between junction and ambient temperature. The maximum power dissipation can be calculated by the following formula : P D(MAX) = (T J(MAX) - T A ) / θJAwhere T J(MAX) is the maximum junction temperature, T A is the ambient temperature, and θJA is the junction to ambient thermal resistance.For recommended operating condition specifications, the maximum junction temperature is 125︒C. The junction to ambient thermal resistance, θJA , is layout dependent. For WQFN-16L 3x3 package, the thermal resistance, θJA , is 30︒C/W on a standard JEDEC 51-7 four-layer thermal test board. The maximum power dissipation at T A = 25︒C can be calculated by the following formula :P D(MAX) = (125︒C - 25︒C) / (30︒C/W) = 3.33W for WQFN-16L 3x3 packageThe maximum power dissipation depends on the operating ambient temperature for fixed T J(MAX) and thermal resistance, θJA . The derating curve in Figure 3 allows the designer to see the effect of rising ambient temperature on the maximum power dissipation.Figure 3. Derating Curve of Maximum PowerDissipationLayout ConsiderationFor the best performance of RT4720A, thefollowing PCB layout guidelines should be strictly followed.④ For good regulation, place the power components asclose to the IC as possible. The traces should be wide and short, especially for the high current output loop.④ The input and output bypass capacitor should be placed as close to the IC as possible and connected to the ground plane of the PCB.④ Minimize the size of the LX1, LX2, LX3 nodes andkeep the traces wide and short. Care should be taken to avoid running traces that carry any noise-sensitive signals near LX or high-current traces.④ Separate power ground (PGND) and analog ground (AGND). Connect the AGND and the PGND islands at a single end. Make sure that there are no otherconnections between these separate ground planes. ④ Connect the exposed pad to a strong ground planefor maximum thermal dissipation.0.00.40.81.21.62.02.42.83.23.64.00255075100125Ambient Temperature (°C)M a x i m u m P o w e r D i s s i p a t i o n (W )Figure 4. PCB Layout GuideOutline DimensionW-Type 16L QFN 3x3 PackageRichtek Technology Corporation14F, No. 8, Tai Yuen 1st Street, Chupei CityHsinchu, Taiwan, R.O.C.Tel: (8863)5526789Richtek products are sold by description only. Richtek reserves the right to change the circuitry and/or specifications without notice at any time. Customers should obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. Richtek cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Richtek product. Information furnished by Richtek is believed to be accurate and reliable. However, no responsibility is assumed by Richtek or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Richtek or its subsidiaries.。