IS200VAICH1D处理器模块
计算满载电流下的电感器峰值电流
以确保电感器不会饱和。峰值电流可能明显高于输出电流，尤其是在电感更小、负载更轻的情况下，所以不要忽略这一步骤。粉状铁芯是可以原谅的，因为它们饱和得很轻，而铁氧体铁芯饱和得很快，其他铁芯材料介于两者之间。以下公式假设连续模式操作，但对于非连续模式，其误差仅略高，因此适用于所有条件。APPLICATIO S I FOR ATIO UU W U 9 LT1370 sn1370 1370fs APPLICATION S I FOR ATIO UUW U测试了低ESR，因此它们给出了给定卷的最低ESR。为了进一步降低ESR，可以并联使用多个输出电容器。微法的数值不是特别关键，从22µF到大于500µF的数值都很好，但你不能在ESR上欺骗大自然。如果你发现一个微小的22µF固体钽电容器，它将具有高ESR，输出纹波电压将非常糟糕。
表面安装电容器
一些典型的固体钽表面安装电容器。表1.表面安装固体钽电容器ESR和纹波电流E外壳尺寸ESR（最大Ω) 纹波电流（A）AVX TPS，Sprague 593D 0.1至0.3 0.7至1.1 AVX TAJ 0.7至0.9 0.4 D外壳尺寸AVX TPS，Sprague 593D 0.1至0.3 0.7至1.1 AVX TAJ 0.9至2.0 0.36至0.24 C外壳尺寸AVX TPS 0.2（典型）0.5（典型）AVX TAK 1.8至3.0 0.22至0.17 B外壳尺寸AVX TAJ 2.5至10 0.16至0.08许多工程师听说，如果固体钽电容器承受高浪涌电流，则容易发生故障。这在历史上是正确的，AVX型TPS电容器是专门测试浪涌能力的，但浪涌强度不是输出电容器的关键问题。固体钽电容器在非常高的导通电涌期间发生故障，这在调节器的输出端不会发生。高放电浪涌，例如当调节器输出完全短路时，不会损坏电容器。单电感升压稳压器在输出电容器中具有大的RMS纹波电流，必须对其进行额定以处理电流。计算公式为：输出电容器纹波电流（RMS）IRIPPLE（RMS）=IOUT=IOUT VOUT–VIN VIN DC 1–DC DC=开关占空比IPEAK=（IOUT）VIN=最小输入电压f=500kHz开关频率+VOUT VIN VIN（VOUT-VIN）））2（f）（L）（VOUT）
Calculate the inductor peak current at full load current
To ensure that the inductor is not saturated. The peak current may be significantly higher than the output current, especially when the inductance is smaller and the load is lighter, so do not ignore this step. Powdered cores are forgivable because they saturate very lightly, while ferrite cores saturate very quickly, and other core materials fall somewhere in between. The following formula assumes continuous mode operation, but for discontinuous mode, its error is only slightly higher, so it is applicable to all conditions. APPLICATIO S I FOR ATIO UU W U 9 LT1370 sn1370 1370fs APPLICATION S I FOR ATIO UUW U tested low ESR, so they give the lowest ESR for a given volume. To further reduce ESR, multiple output capacitors can be used in parallel. The value of the micro method is not particularly critical. The values from 22 µ F to more than 500 µ F are very good, but you can't cheat nature on ESR. If you find a tiny 22 µ F solid tantalum capacitor, it will have a high ESR and the output ripple voltage will be very bad.
Surface mounted capacitor
Some typical solid tantalum surface mount capacitors. Table 1. Surface mounted solid tantalum capacitors ESR and ripple current E Case size ESR (maximum Ω) Ripple current (A) AVX TPS, Sprague 593D 0.1 to 0.3 0.7 to 1.1 AVX TAJ 0.7 to 0.9 0.4 D Case size AVX TPS, Sprague 593D 0.1 to 0.3 0.7 to 1.1 AVX TAJ 0.9 to 2.0 0.36 to 0.24 C Case size AVX TPS 0.2 (typical) 0.5 (typical) AVX TAK 1.8 to 3.0 0.22 to 0.17 B Case size AVX TAJ 2.5 to 10 0.16 to 0.08 Many engineers have heard that, If solid tantalum capacitors bear high inrush current, they are prone to failure. This is correct in history. AVX TPS capacitor is specially used to test the surge capacity, but the surge strength is not the key problem of the output capacitor. Solid tantalum capacitors fail during very high conduction surges, which do not occur at the output of the regulator. High discharge surge, such as when the regulator output is completely short circuited, will not damage the capacitor. The single inductance boost voltage regulator has a large RMS ripple current in the output capacitor, which must be rated to handle the current. The calculation formula is: output capacitor ripple current (RMS) IRIPPLE (RMS)=IOUT=IOUT VOUT – VIN DC 1 – DC DC=switch duty cycle IPEAK=(IOUT) VIN=minimum input voltage f=500kHz switching frequency+VOUT VIN VIN (VOUT-VIN)) 2 (f) (L) (VOUT)
