FCP280 RH924YA自動(dòng)化模塊
輸入電容器
升壓轉(zhuǎn)換器的輸入電容器不那么關(guān)鍵，因?yàn)檩斎腚娏鞑ㄐ问侨切蔚模⑶也话敵鲭娙萜髦邪l(fā)現(xiàn)的大的方波電流。10μF至100μF范圍內(nèi)的電容器，ESR為0.1? 或更少的工作很好，直到全6A開(kāi)關(guān)電流。在低開(kāi)關(guān)電流下，可以接受較高的ESR電容器。升壓變換器的輸入電容器紋波電流為：IRIPPLE=f=500kHz開(kāi)關(guān)頻率0.3（VIN）（VOUT–VIN）。幾家制造商已經(jīng)開(kāi)發(fā)了專門測(cè)試?yán)擞磕芰Φ你g電容器（例如AVX TPS系列），但如果在高浪涌期間輸入電壓接近電容器的最大額定電壓，即使這些裝置也可能出現(xiàn)故障。
鋁電解電容器
AVX建議在高電涌應(yīng)用中將電容器電壓降低2:1。也可以使用陶瓷、OS-CON和鋁電解電容器，并且對(duì)導(dǎo)通電涌具有高耐受性。陶瓷電容器價(jià)值更高、成本更低的陶瓷電容器現(xiàn)在可用于更小的外殼尺寸。由于它們的ESR非常低，因此對(duì)于開(kāi)關(guān)穩(wěn)壓器來(lái)說(shuō)很有吸引力。不幸的是，ESR太低，可能導(dǎo)致環(huán)路穩(wěn)定性問(wèn)題。固體鉭電容器ESR在5kHz至50kHz產(chǎn)生環(huán)路“零”，這有助于提供可接受的環(huán)路相位裕度。陶瓷電容器在超過(guò)300kHz時(shí)保持電容性，通常在ESR生效之前與ESL共振。由于其高紋波電流額定值和對(duì)接通浪涌的耐受性，它們適合于輸入旁路。
Input capacitor
The input capacitor of the boost converter is less critical because the input current waveform is triangular and does not include the large square wave current found in the output capacitor. Capacitors in the range of 10 μ F to 100 μ F with an ESR of 0.1 ? or less work well until the full 6A switching current. Higher ESR capacitors can be accepted at low switching current. Ripple current of input capacitor of boost converter: IRIPPLE=f=500kHz switching frequency 0.3 (VIN) (VOUT – VIN). Several manufacturers have developed tantalum capacitors (such as AVX TPS series) for testing surge capacity, but if the input voltage is close to the maximum rated voltage of the capacitor during high surge, even these devices may fail.
Aluminum electrolytic capacitor
AVX recommends reducing the capacitor voltage by 2:1 in high surge applications. Ceramic, OS-CON and aluminum electrolytic capacitors can also be used and have high resistance to conducting surges. Ceramic capacitors, which have higher value and lower cost, can now be used for smaller case sizes. Because their ESR is very low, they are very attractive for switching regulators. Unfortunately, ESR is too low, which may cause loop stability problems. The solid tantalum capacitor ESR generates a loop "zero" at 5kHz to 50kHz, which helps to provide an acceptable loop phase margin. Ceramic capacitors maintain capacitance when exceeding 300kHz, and usually resonate with ESL before ESR takes effect. They are suitable for input bypass due to their high ripple current rating and resistance to switching surges.
