IC基本电气特性-华为内部员工培训资料.doc

IC基本电气特性 Quiescent current 静态电流 Standby current低功耗电流 Dropout voltage (LDO特性)压降的输入电压 Efficiency功率 Transient response顺势特性 Line regulation线路调整器 Load regulation负载调整率 Power supply rejection电源排除/抑制 Noise Accuracy精确性 IC量测 IC（LDO）结构框图 Capacitor电容 reference参考（电压）error amplifier误差信号放大器 Pass element无源元件（二极管）dynamic load 动态负载 主要模块包括; Voltage Reference参考（电压）Error Amplifier误差信号放大器 Feedback Network 反馈网络 Series-pass Element无源元件（二极管） 优点：简单、输出纹波电压低 、出色的 line 和负载稳压、对负载和 line 的变化响应迅速 、电磁干扰 (EMI) 低 缺点：效率低 、如果需要冷却设备，则要求较大的空间 IC基本电气特性－Quiescent Current Standby Current Quiescent Current(Ground current): The difference between input and output。 Low quiescent current is necessary to maximize the efficiency. 低静态电流是最大限度地提高效率必要条件 。 Standby Current: The input current drawn by a regulator when the output voltage is disabled by a shutdown signal. Quiescent Current and Output Current The value of quiescent current is mostly determined by the series pass element, topologies, ambient temperature, etc. 静态电流的值主要是一系列无源元件，拓扑结构，环境温度等 确定的 具体特性与IC结构、制程密切相关 IC基本电气特性－ Dropout Voltage（特有规格） Low-Dropout Linear Regulators 低压差线性稳压器 传统的三端稳压器如：LM78xx Vdrop的典型值是2V，看到很多7805应用 时都会背着一个散热器。 LM317 2V LM1117 1.2V。 调整管采用的结构 LM317 输出 Darlingtong Vdrop=Vsat+2Vbe 1.6~2.5V NPN Vdrop=Vsat+Vbe 0.9V PNP Vdrop=Vsat 0.15~0.4V PMOS Vdrop=Io X Ron 35~350mv NMOS Vdrop=Vsat+Vgs 1V 不同调整管结构的比较： The NMOS pass element is most advantageous due to its low on resistance. Unfortunately, the gate drive difficulties make it less than ideal in applicaitons and as a result there are few NMOS LDOs available. 传统上，PNP双极型晶体管应用到低压线性稳压器，主要是因为它很容易实现了低压降电压。 Traditionally, the PNP bipolar transistor has been applied to low dropout applications, primarily because it easily enables a low drop out voltage. However, it has a high quiescent current and low efficiency, which are not ideal in applications where m